Cascade Reactions in Nanozymes: Spatially Separated Active Sites inside Ag-Core-Porous-Cu-Shell Nanoparticles for Multistep Carbon Dioxide Reduction to Higher Organic Molecules

Tandem modulation strategy for copper-based catalysts: Towards efficient C-C coupling in the electrochemical reduction of carbon dioxide

The CO2 reduction reaction (CO2RR) is notable for its multiple advantages, such as mild reaction conditions, controllable product output, and ease of operation. The chemistry of CO2RR to produce multicarbon products involves multiple electron-proton transfer steps, in which the adsorption of CO intermediates is usually the key rate-determining step of the reaction. Currently, Cu is the only metal catalyst known to efficiently reduce CO2 to multicarbon products, mainly due to its appropriate adsorption energy for CO intermediates. However, single Cu catalysts often face challenges such as excessively high overpotentials and poor selectivity, which limit their potential application in CO2 reduction. In recent years, electrochemical CO2 reduction using copper-based tandem catalysts has become an effective strategy to enhance the overall performance of CO2RR and a hot topic in the research field. Here we review recent research advances in the field of electrochemical CO2RR where tandem methods have been applied. The major points are the following: (1) the tandem process allows for more precise control of the electrochemical reduction pathway, thereby increasing the yield of the target product while reducing the generation of by-products; (2) Mass transportation of *CO intermediates and spatial management is important for the generation of multicarbon products; (3) a variety of tandem means for upgrading the product to a deeply reduced product are reviewed.

Electroreduction of CO2 to Methanol Using a Coordination-Moiety-Anchored Carbon-Based Electrode

Electrochemical reduction of carbon dioxide (CO2ER) has gained wide attention lately because of its potential to create a closed carbon loop, offering a sustainable solution toward environmental as well as energy crisis. However, the key challenge lies in the selective conversion of CO2 into electrofuels, such as methanol, which necessitates six proton-coupled electron transfers. In this work, we report the first instance of an electrochemically prepared Cu-coordinated 2,5-dimercapto-1,3,4-thiadiazole-modified carbon fiber paper electrode (CDM@CFP). The hence-engineered novel electrode was applied for the CO2ER reaction to produce methanol exclusively with an F.E. of 59.6% at a low potential of -0.73 V versus RHE. Unlike most of the copper-based electrocatalysts, which result in multiple hydrocarbons, here, we have optimized a potential-dependent selectivity for maximum efficiency, which is a significant milestone in the field.

A facile colorimetric sensor based on Fe3O4 magnetic nanoparticles with intrinsic catalytic activity for the rapid and selective detection of ochratoxin A

Ochratoxin A (OTA) is recognized as a Group 2B carcinogen and poses significant dangers to human, making it crucial to regulate OTA levels in food products. Herein, we developed a colorimetric approach to analyze OTA utilizing the intrinsic catalytic oxidized activity of Fe3O4 magnetic nanoparticles (MNPs). Our findings reveal that OTA shows a significant impact on the absorbance signal of the catalytic system, notably reducing the absorbance at 532 nm with H2O2 and 4-aminoantipyrene (4-AP). This sensor does not require elaborate aptamer or antibody, omitting the cumbersome reaction and the loss during synthesis, thus simply realizing OTA detection. The signal correlates linearly with the OTA concentrations and achieves satisfied sensitivity. The practical application has been verified utilizing beer and rice samples, resulting in recoveries ranging from 91.0 % to 106.2 %. This accuracy and reliability verified the method feasibility for monitoring OTA levels in food products.

Structural Regulating of Cu-Based Metallic Electrocatalysts for CO2 to C2+ Products Conversion

Electrochemical carbon dioxide reduction reaction (CO2RR) to highly value-added multi-carbon (C2+) fuels or chemicals is a promising pathway to address environment issues and energy crisis. In the periodic table, Cu as only the candidate can convert CO2 to C2+ products such as C2H4 and C2H5OH due to the suitable absorption energy to reaction intermediate. However, application of Cu is limited for its low activity and poor selectivity. The tandem catalytic strategy can effectively solve the problems caused by single copper catalyst. In tandem catalysis, how to promote the formation, transport, adsorption and coupling of the important intermediate CO is the key issue to improve the selectivity of C2+ products. Regulating the structure of Cu-based bimetallic can effectively promote these processes to Electrochemical CO2RR on account of its synergistic effect, electronic effect and interfacial interaction. In this review, we systematically summarized the relationship between structure of Cu-based bimetallic catalysts with performance of electrochemical CO2RR. More importantly, we reveal that different Cu-based bimetallic structures enhance the activity and selectivity of the catalysts by regulating the processes such as the transport and adsorption of the reaction intermediate CO. Then, we proposed well-effective strategies to rationally design Cu-based metallic catalysts. Finally, we put forward some challenges and opportunities that Cu-based bimetallic catalysts would face in the development of electrochemical CO2RR technology in the future.

Theoretical computation of C-C coupling reactions by different C1 intermediates at Cun and Cun-1Ag clusters supported on TiO2

*CO dimerization is a well-known pathway for C-C bond formation, producing C2+ products. However, the mechanisms of C-C coupling between other C1 intermediates remain less explored. In this study, we investigate C-C bond formation involving *CO, *CHO, *COH, and other C1 intermediates on Cun and Cun-1Ag clusters supported on TiO2. Interestingly, our results reveal that the activation energy for *CO dimerization is not the lowest, indicating that it is not the dominant pathway for C-C bond formation. Coupling reactions involving *CHO, *COH, and other C1 intermediates exhibit lower activation energies. Furthermore, the activation energy for the same reaction varies across different Cun clusters, emphasizing the role of cluster selection in C-C coupling. Notably, on certain clusters, such as Cu8, the activation energy for C-C bond formation at the Ag site is lower than that at the Cu site, suggesting that Ag doping can enhance C-C coupling. However, in larger clusters like Cu13, the activation energy at the Ag site exceeds that at the Cu site, highlighting that the effect of Ag doping is cluster size dependent. This study provides new insights into C-C bond formation, offering guidance for designing efficient co-catalysts to produce high-value C2+ products.

A Pulsed Tandem Electrocatalysis Strategy for CO2 Reduction

Electroreduction of CO2 to value-added C2 products remains hindered by sluggish C-C coupling kinetics and competing side reactions. Inspired by the tandem catalytic mechanisms of multienzyme systems, we designed a dual-site single-atom nanozyme (DSAN) comprising FeN4 and FeO4 sites (FeN4-FeO4). Density functional theory (DFT) calculations under constant potential reveal that the FeN4 site functions as a CO generator, while the FeO4 site facilitates CO migration, C-C coupling, and subsequent C2 product formation. To further optimize the catalytic efficiency, we introduced a pulsed electrocatalysis strategy by alternating between zero potential and -0.7 V. This approach dynamically modulates active-site functions: at -0.70 V, CO2 adsorption and *CH3CH2OH formation are facilitated, while at 0 V, CO migration and C-C coupling are enhanced due to the spin-state transitions during potential switching. Additionally, the zero potential suppresses excessive hydrogenation of key intermediates, thereby improving CH3CH2OH selectivity. These findings highlight the synergistic strategy integrating tandem catalysis and pulsed potential control, offering a novel and effective approach for CO2-to-C2 conversion using SAN catalysts.

Strategies for Enhancing Stability in Electrochemical CO2 Reduction

The electrochemical CO2 reduction reaction (CO2RR) holds significant promise as a sustainable approach to address global energy challenges and reduce carbon emissions. However, achieving long-term stability in terms of catalytic performance remains a critical hurdle for large-scale commercial deployment. This mini-review provides a comprehensive exploration of the key factors influencing CO2RR stability, encompassing catalyst design, electrode architecture, electrolyzer optimization, and operational conditions. We examine how catalyst degradation occurs through mechanisms such as valence changes, elemental dissolution, structural reconfiguration, and active site poisoning and propose targeted strategies for improvement, including doping, alloying, and substrate engineering. Additionally, advancements in electrode design, such as structural modifications and membrane enhancements, are highlighted for their role in improving stability. Operational parameters such as temperature, pressure, and electrolyte composition also play crucial roles in extending the lifespan of the reaction. By addressing these diverse factors, this review aims to offer a deeper understanding of the determinants of long-term stability in the CO2RR, laying the groundwork for the development of robust, scalable technologies for efficient carbon dioxide conversion.

Cascade Catalytic Systems for Converting CO2 into C2+ Products

The excessive emission and continuous accumulation of CO2 have precipitated serious social and environmental issues. However, CO2 can also serve as an abundant, inexpensive, and non-toxic renewable C1 carbon source for synthetic reactions. To achieve carbon neutrality and recycling, it is crucial to convert CO2 into value-added products through chemical pathways. Multi-carbon (C2+) products, compared to C1 products, offer a broader range of applications and higher economic returns. Despite this, converting CO2 into C2+ products is difficult due to its stability and the high energy required for C-C coupling. Cascade catalytic reactions offer a solution by coordinating active components, promoting intermediate transfers, and facilitating further transformations. This method lowers energy consumption. Recent advancements in cascade catalytic systems have allowed for significant progress in synthesizing C2+ products from CO2. This review highlights the features and advantages of cascade catalysis strategies, explores the synergistic effects among active sites, and examines the mechanisms within these systems. It also outlines future prospects for CO2 cascade catalytic synthesis, offering a framework for efficient CO2 utilization and the development of next-generation catalytic systems.

From Nanozymes to Multi-Purpose Nanomaterials: The Potential of Metal-Organic Frameworks for Proteomics Applications

Metal-organic frameworks (MOFs) have the potential to revolutionize the biotechnological and medical landscapes due to their easily tunable crystalline porous structure. Herein, the study presents MOFs' potential impact on proteomics, unveiling the diverse roles MOFs can play to boost it. Although MOFs are excellent catalysts in other scientific disciplines, their role as catalysts in proteomics applications remains largely underexplored, despite protein cleavage being of crucial importance in proteomics protocols. Additionally, the study discusses evolving MOF materials that are tailored for proteomics, showcasing their structural diversity and functional advantages compared to other types of materials used for similar applications. MOFs can be developed to seamlessly integrate into proteomics workflows due to their tunable features, contributing to protein separation, peptide enrichment, and ionization for mass spectrometry. This review is meant as a guide to help bridge the gap between material scientists, engineers, and MOF chemists and on the other side researchers in biology or bioinformatics working in proteomics.

sp Carbon Disrupting Axial Symmetry of Local Electric Field for Biomimetic Construction of Three-Dimensional Geometric and Electronic Structure in Nanozyme for Sensing and Microplastic Degradation

The catalytic efficiency of natural enzymes depends on the precise electronic interactions between active centers and cofactors within a three-dimensional (3D) structure. Single-atom nanozymes (SAzymes) attempt to mimic this structure by modifying metal active sites with molecular ligands. However, SAzymes struggle to match the catalytic efficiency of natural enzymes due to constraints in active site proximity, quantity, and the inability to simulate electron transfer processes driven by internal electronic structures of natural enzymes. This study introduces a universal spatial engineering strategy in which molecular ligands are replaced with graphdiyne (GDY) to induce d-π orbital hybridization with copper nanoparticles (Cu NPs), leading to an asymmetric electron-rich distribution along the longitudinal axis that mimics the local electric field of natural laccase. Moreover, multiple sp bonds within GDY scaffold effectively anchor Cu NPs, facilitating the construction of 3D geometric structure similar to that of natural laccase. An enzymatic activity of 82.53 U mg-1 is achieved, 4.72 times higher than that of natural laccase. By reconstructing both 3D structures and local electric fields of natural enzymes through d-π orbital hybridization, this approach enhances electron interactions between cofactors, active centers, and substrates, and offers a versatile framework for biomimetic design of nanozymes.

An Array of Glucose Nanozymes That Can Selectively Detect Glucose in Whole Blood

Achieving sensors that can sensitively and selectively quantify levels of analytes in complex biofluids such as blood remains a significant challenge. To address this, we synthesized an array of isolated carbon nanochannels on a flat gold electrode that function as molecular sieves to prevent protein fouling and eliminate the need for antifouling layers. Utilizing a two-step pulsed technique, a reductive pulse expels negative interferences and fouling molecules followed by an oxidative pulse that oxidizes glucose at the bottom of the channel and on the gold surface. The nanoconfined environment created by the top carbon nanochannel layer (6 nm diameter, 21 nm length confirmed by TEM and SEM), with redox pulses enabled the gold catalytic center to generate hydroxide ions, fostering a higher pH environment favorable for glucose oxidation. The nonenzymatic approach to detecting glucose was shown to give equivalent data directly in whole blood to that achieved by using an enzyme blood glucose meter determined using a Clark Error Grid. This simplified sensor design, suitable for wearable systems, offers a solution for glucose monitoring in complex biofluids with a far greater stability over time.

Understanding the chemistry of mesostructured porous nanoreactors

Porous nanoreactors mimic the structures and functions of cells, providing an adaptable material with multiple functions and effects. These reactors can be nanoscale containers and shuttles or catalytic centres, drawing in reactants for cascading reactions with multishelled designs. The detailed construction of multi-level reactors at the nanometre scale remains a great challenge, but to regulate the reaction pathways within a reactor, designs of great intricacy are required. In this Review, we define the basic structural characteristics of porous nanoreactors, while also discussing the design principles and synthetic chemistry of these structures with respect to their emerging applications in energy storage and heterogeneous catalysis. Finally, we describe the difficulties of the structural optimization of these reactors and propose possible ways to improve porous nanoreactor design for future applications.

Electrochemical CO2 Reduction Reaction: Comprehensive Strategic Approaches to Catalyst Design for Selective Liquid Products Formation

The escalating concern regarding the release of CO2 into the atmosphere poses a significant threat to the contemporary efforts in mitigating climate change. Amidst a multitude of strategies for curtailing CO2 emissions, the electrochemical CO2 reduction presents a promising avenue for transforming CO2 molecules into a diverse array of valuable gaseous and liquid products, such as CO, CH3OH, CH4, HCO2H, C2H4, C2H5OH, CH3CO2H, 1-C3H7OH and others. The mechanistic investigations of gaseous products (e. g. CO, CH4, C2H4, C2H6 and others) broadly covered in the literature. There is a noticeable gap in the literature when it comes to a comprehensive summary exclusively dedicated to coherent roadmap for the designing principles for a selective catalyst all possible liquid products (such as CH3OH, C2H5OH, 1-C3H7OH, 2-C3H7OH, 1-C4H9OH, as well as other C3-C4 products like methylglyoxal and 2,3-furandiol, in addition to HCO2H, AcOH, oxalic acid and others), selectively converted by CO2 reduction. This entails a meticulous analysis to justify these approaches and a thorough exploration of the correlation between materials and their electrocatalytic properties. Furthermore, these insightful discussions illuminate the future prospects for practical applications, a facet not exhaustively examined in prior reviews.

Nanozymes: a bibliometrics review

As novel multifunctional materials that merge enzyme-like capabilities with the distinctive traits of nanomaterials, nanozymes have made significant strides in interdisciplinary research areas spanning materials science, bioscience, and beyond. This article, for the first time, employed bibliometric methods to conduct an in-depth statistical analysis of the global nanozymes research and demonstrate research progress, hotspots and trends. Drawing on data from the Web of Science Core Collection database, we comprehensively retrieved the publications from 2004 to 2024. The burgeoning interest in nanozymes research across various nations indicated a growing and widespread trend. This article further systematically elaborated the enzyme-like activities, matrix, multifunctional properties, catalytic mechanisms and various applications of nanozymes, and the field encounters challenges. Despite notable progress, and requires deeper exploration guide the future research directions. This field harbors broad potential for future developments, promising to impact various aspects of technology and society.

Directional co-immobilization of artificial multimeric-enzyme complexes as a robust biocatalyst for biosynthesis curcumin glucosides and regeneration of UDP-glucose

Site-directed protein immobilization allows the homogeneous orientation of proteins while maintaining high activity, which is advantageous for various applications. In this study, the use of SpyCatcher/SpyTag technology and magnetic nickel ferrite (NiFe2O4 NPs) nanoparticles were used to prepare a site-directed immobilization of BsUGT2m from Bacillus subtilis and AtSUSm from Arabidopsis thaliana for enhancing curcumin glucoside production with UDP-glucose regeneration from sucrose and UDP. The immobilization of self-assembled multienzyme complex (MESAs) enzymes were characterized for immobilization parameters and stability, including thermal, pH, storage stability, and reusability. The immobilized MESAs exhibited a 2.5-fold reduction in UDP consumption, enhancing catalytic efficiency. Moreover, the immobilized MESAs demonstrated high storage and temperature stability over 21 days at 4 °C and 25 °C, outperforming their free counterparts. Reusability assays showed that the immobilized MESAs retained 78.7 % activity after 10 cycles. Utilizing fed-batch technology, the cumulative titer of curcumin 4'-O-β-D-glucoside reached 6.51 mM (3.57 g/L) and 9.45 mM (5.18 g/L) for free AtSUSm/BsUGT2m and immobilized MESAs, respectively, over 12 h. This study demonstrates the efficiency of magnetic nickel ferrite nanoparticles in co-immobilizing enzymes, enhancing biocatalysts' catalytic efficiency, reusability, and stability.

Challenges and Opportunities for Single-Atom Electrocatalysts: From Lab-Scale Research to Potential Industry-Level Applications

Single-atom electrocatalysts (SACs) are a class of promising materials for driving electrochemical energy conversion reactions due to their intrinsic advantages, including maximum metal utilization, well-defined active structures, and strong interface effects. However, SACs have not reached full commercialization for broad industrial applications. This review summarizes recent research achievements in the design of SACs for crucial electrocatalytic reactions on their active sites, coordination, and substrates, as well as the synthesis methods. The key challenges facing SACs in activity, selectivity, stability, and scalability, are highlighted. Furthermore, it is pointed out the new strategies to address these challenges including increasing intrinsic activity of metal sites, enhancing the utilization of metal sites, improving the stability, optimizing the local environment, developing new fabrication techniques, leveraging insights from theoretical studies, and expanding potential applications. Finally, the views are offered on the future direction of single-atom electrocatalysis toward commercialization.

Nanozymes-Mediated Cascade Reaction System for Tumor-Specific Diagnosis and Targeted Therapy

Cascade reactions are described as efficient and versatile tools, and organized catalytic cascades can significantly improve the efficiency of chemical interworking between nanozymes. They have attracted great interest in many fields such as chromogenic detection, biosensing, tumor diagnosis, and therapy. However, how to selectively kill tumor cells by enzymatic reactions without harming normal cells, as well as exploring two or more enzyme-engineered nanoreactors for cascading catalytic reactions, remain great challenges in the field of targeted and specific cancer diagnostics and therapy. The latest research advances in nanozyme-catalyzed cascade processes for cancer diagnosis and therapy are described in this article. Here, various sensing strategies are summarized, for tumor-specific diagnostics. Targeting mechanisms for tumor treatment using cascade nanozymes are classified and analyzed, "elements" and "dimensions" of cascade nanozymes, types, designs of structure, and assembly modes of highly active and specific cascade nanozymes, as well as a variety of new strategies of tumor targeting based on the cascade reaction of nanozymes. Finally, the integrated application of the cascade nanozymes systems in tumor-targeted and specific diagnostic therapy is summarized, which will lay the foundation for the design of more rational, efficient, and specific tumor diagnostic and therapeutic modalities in the future.

Exploring Nanozymes for Organic Substrates: Building Nano-organelles

Since the discovery of the first peroxidase nanozyme (Fe3O4), numerous nanomaterials have been reported to exhibit intrinsic enzyme-like activity toward inorganic oxygen species, such as H2O2, oxygen, and O2 -. However, the exploration of nanozymes targeting organic compounds holds transformative potential in the realm of industrial synthesis. This review provides a comprehensive overview of the diverse types of nanozymes that catalyze reactions involving organic substrates and discusses their catalytic mechanisms, structure-activity relationships, and methodological paradigms for discovering new nanozymes. Additionally, we propose a forward-looking perspective on designing nanozyme formulations to mimic subcellular organelles, such as chloroplasts, termed "nano-organelles". Finally, we analyze the challenges encountered in nanozyme synthesis, characterization, nano-organelle construction and applications while suggesting directions to overcome these obstacles and enhance nanozyme research in the future. Through this review, our goal is to inspire further research efforts and catalyze advancements in the field of nanozymes, fostering new insights and opportunities in chemical synthesis.

Unleashing the Potential of Single-Atom Nanozymes: Catalysts for the Future

Single-atom nanozymes (SANs) have become a breakthrough in atomically precise catalysis, which relies on the catalytic active site formed by the single-atom itself. From this angle, SANs and their advantages compared to natural enzymes as well as spaces for their application are emphasized. The SANs have outstanding control over their catalytic activities; this is compared with bulk materials and natural enzymes. The structure of the SANs has very promising potential for the next generation of biosensing and biomedical devices and environmental remediation. Although their capabilities are high, difficulties still arise. The specificity, scalability, biosafety, and catalysis mechanisms raise additional issues that require further research. We build up a vision of the perspectives of the better implementation of SANs, which are designed for diagnostic purposes, improving industrial technologies, and creating new sustainable technologies in the food processing industry. AI and machine learning systems may clarify the structure-performance relationship of SANs for improved material and process selectivity. The future of SANs is very promising, and by addressing these challenges and leveraging advancements in artificial intelligence and materials science, SANs have the potential to become powerful tools for a sustainable future.

High-efficiency C3 electrosynthesis on a lattice-strain-stabilized nitrogen-doped Cu surface

The synthesis of multi-carbon (C2+) fuels via electrocatalytic reduction of CO, H2O using renewable electricity, represents a significant stride in sustainable energy storage and carbon recycling. The foremost challenge in this field is the production of extended-chain carbon compounds (Cn, n ≥ 3), wherein elevated *CO coverage (θco) and its subsequent multiple-step coupling are both critical. Notwithstanding, there exists a "seesaw" dynamic between intensifying *CO adsorption to augment θco and surmounting the C-C coupling barrier, which have not been simultaneously realized within a singular catalyst yet. Here, we introduce a facilely synthesized lattice-strain-stabilized nitrogen-doped Cu (LSN-Cu) with abundant defect sites and robust nitrogen integration. The low-coordination sites enhance θco and concurrently, the compressive strain substantially fortifies nitrogen dopants on the catalyst surface, promoting C-C coupling activity. The n-propanol formation on the LSN-Cu electrode exhibits a 54% faradaic efficiency and a 29% half-cell energy efficiency. Moreover, within a membrane electrode assembly setup, a stable n-propanol electrosynthesis over 180 h at a total current density of 300 mA cm-2 is obtained.

Single Entity Electrocatalysis

Making a measurement over millions of nanoparticles or exposed crystal facets seldom reports on reactivity of a single nanoparticle or facet, which may depart drastically from ensemble measurements. Within the past 30 years, science has moved toward studying the reactivity of single atoms, molecules, and nanoparticles, one at a time. This shift has been fueled by the realization that everything changes at the nanoscale, especially important industrially relevant properties like those important to electrocatalysis. Studying single nanoscale entities, however, is not trivial and has required the development of new measurement tools. This review explores a tale of the clever use of old and new measurement tools to study electrocatalysis at the single entity level. We explore in detail the complex interrelationship between measurement method, electrocatalytic material, and reaction of interest (e.g., carbon dioxide reduction, oxygen reduction, hydrazine oxidation, etc.). We end with our perspective on the future of single entity electrocatalysis with a key focus on what types of measurements present the greatest opportunity for fundamental discovery.

Ultrasensitive cortisol electrochemical immunosensor amplifying by Au single-atom nanozymes and HRP enzymes

Cortisol, a corticosteroid hormone as a primary stress hormone response to internal and external stress, has been regarded as a gold standard reliable biomarker to evaluate human mental stress. The double enzymes strategy, using nanozyme and enzyme amplifying the electrochemical signal, has been widely used to improve the performance of electrochemical biosensors. An ultra-sensitive electrochemical cortisol sensor based on Au single-atom nanozymes had been fabricated through HRP labeled anti-cortisol antibody binding with Au by Au-S bond. Based on the high catalytic activity of Au single-atom nanozymes and the high selectivity of HRP-labeled anti-cortisol antibodies, the cortisol electrochemical sensor-based Au single-atom nanozymes had an excellent response to cortisol, such as high electrochemical activity, high sensitivity, high selectivity, and wide linear range (0.15-300 ng mL-1) and low detection (0.48 pg mL-1) through the four-parameter logistic model with 95% confidence. The electrochemical cortisol sensor was used to determine the cortisol concentration of human saliva at different times.

Nanozymes with biomimetically designed properties for cancer treatment

Nanozymes, as a type of nanomaterials with enzymatic catalytic activity, have demonstrated tremendous potential in cancer treatment owing to their unique biomedical properties. However, the heterogeneity of tumors and the complex tumor microenvironment pose significant challenges to the in vivo catalytic efficacy of traditional nanozymes. Drawing inspiration from natural enzymes, scientists are now using biomimetic design to build nanozymes from the ground up. This approach aims to replicate the key characteristics of natural enzymes, including active structures, catalytic processes, and the ability to adapt to the tumor environment. This achieves selective optimization of nanozyme catalytic performance and therapeutic effects. This review takes a deep dive into the use of these biomimetically designed nanozymes in cancer treatment. It explores a range of biomimetic design strategies, from structural and process mimicry to advanced functional biomimicry. A significant focus is on tweaking the nanozyme structures to boost their catalytic performance, integrating them into complex enzyme networks similar to those in biological systems, and adjusting functions like altering tumor metabolism, reshaping the tumor environment, and enhancing drug delivery. The review also covers the applications of specially designed nanozymes in pan-cancer treatment, from catalytic therapy to improved traditional methods like chemotherapy, radiotherapy, and sonodynamic therapy, specifically analyzing the anti-tumor mechanisms of different therapeutic combination systems. Through rational design, these biomimetically designed nanozymes not only deepen the understanding of the regulatory mechanisms of nanozyme structure and performance but also adapt profoundly to tumor physiology, optimizing therapeutic effects and paving new pathways for innovative cancer treatment.

Engineering Spin Polarization of the Surface-Adsorbed Fe Atom by Intercalating a Transition Metal Atom into the MoS2 Bilayer for Enhanced Nitrogen Reduction

The precise control of spin states in transition metal (TM)-based single-atom catalysts (SACs) is crucial for advancing the functionality of electrocatalysts, yet it presents significant scientific challenges. Using density functional theory (DFT) calculations, we propose a novel mechanism to precisely modulate the spin state of the surface-adsorbed Fe atom on the MoS2 bilayer. This is achieved by strategically intercalating a TM atom into the interlayer space of the MoS2 bilayer. Our results show that these strategically intercalated TM atoms can induce a substantial interfacial charge polarization, thereby effectively controlling the charge transfer and spin polarization on the surface Fe site. In particular, by varying the identity of the intercalated TM atoms and their vacancy filling site, a continuous modulation of the spin states of the surface Fe site from low to medium to high can be achieved, which can be accurately described using descriptors composed of readily accessible intrinsic properties of materials. Using the electrochemical dinitrogen reduction reaction (eNRR) as a prototypical reaction, we discovered a universal volcano-like relation between the tuned spin and the catalytic activity of Fe-based SACs. This finding contrasts with the linear scaling relationships commonly seen in traditional studies and offers a robust new approach to modulating the activity of SACs through interfacial engineering.

Recent Advances in Electrocatalytic Hydrogenation Reactions on Copper-Based Catalysts

Hydrogenation reactions play a critical role in the synthesis of value-added products within the chemical industry. Electrocatalytic hydrogenation (ECH) using water as the hydrogen source has emerged as an alternative to conventional thermocatalytic processes for sustainable and decentralized chemical synthesis under mild conditions. Among the various ECH catalysts, copper-based (Cu-based) nanomaterials are promising candidates due to their earth-abundance, unique electronic structure, versatility, and high activity/selectivity. Herein, recent advances in the application of Cu-based catalysts in ECH reactions for the upgrading of valuable chemicals are systematically analyzed. The unique properties of Cu-based catalysts in ECH are initially introduced, followed by design strategies to enhance their activity and selectivity. Then, typical ECH reactions on Cu-based catalysts are presented in detail, including carbon dioxide reduction for multicarbon generation, alkyne-to-alkene conversion, selective aldehyde conversion, ammonia production from nitrogen-containing substances, and amine production from organic nitrogen compounds. In these catalysts, the role of catalyst composition and nanostructures toward different products is focused. The co-hydrogenation of two substrates (e.g., CO2 and NOx n, SO3 2-, etc.) via C─N, C─S, and C─C cross-coupling reactions are also highlighted. Finally, the critical issues and future perspectives of Cu-catalyzed ECH are proposed to accelerate the rational development of next-generation catalysts.

Data-Driven Evolutionary Design of Multienzyme-like Nanozymes

Multienzyme-like nanozymes are nanomaterials with multiple enzyme-like activities and are the focus of nanozyme research owing to their ability to facilitate cascaded reactions, leverage synergistic effects, and exhibit environmentally responsive selectivity. However, multienzyme-like nanozymes exhibit varying enzyme-like activities under different conditions, making them difficult to precisely regulate according to the design requirements. Moreover, individual enzyme-like activity in a multienzyme-like activity may accelerate, compete, or antagonize each other, rendering the overall activity a complex interplay of these factors rather than a simple sum of single enzyme-like activity. A theoretically guided strategy is highly desired to accelerate the design of multienzyme-like nanozymes. Herein, nanozyme information was collected from 4159 publications to build a nanozyme database covering element type, element ratio, chemical valence, shape, pH, etc. Based on the clustering correlation coefficients of the nanozyme information, the material features in distinct nanozyme classifications were reorganized to generate compositional factors for multienzyme-like nanozymes. Moreover, advanced methods were developed, including the quantum mechanics/molecular mechanics method for analyzing the surface adsorption and binding energies of substrates, transition states, and products in the reaction pathways, along with machine learning algorithms to identify the optimal reaction pathway, to aid the evolutionary design of multienzyme-like nanozymes. This approach culminated in creating CuMnCo7O12, a highly active multienzyme-like nanozyme. This process is named the genetic-like evolutionary design of nanozymes because it resembles biological genetic evolution in nature and offers a feasible protocol and theoretical foundation for constructing multienzyme-like nanozymes.

A biocatalytic cascade in enzyme/metal continuous-microflow microgel with stable intermediate channel for point-of-care biosensing

A fast and accurate method for ultrasensitive monitoring of substrate is significant for cascade molecular detection. Here, we synthesize a glucose oxidase (GOx) microgel with iron coordination (Fe/GOx microgel). The microgel is cross-linked by chitosan and iron ion coordination which construct a tubular structure. Powder X-ray diffraction and Brunauer-Emmett-Teller results confirm the tubular crystal structure with a high specific surface area is formed in the microgel. The tubular structure offers a stable channel for intermediate transport which ensures the stabilization for the intermediate transport, and high specific surface area enhances the interaction between substrates and catalysts. As a result, the sensitivity of the Fe/GOx microgel is 175.5 μA mM-1 cm-2 and the lowest detection limit is 4.42 μM. In addition, the nanoscale Fe/GOx microgel also has the characteristics of reusability and maintains its activity after five times of catalysis. The generation of free radicals during the catalytic process can be detected by light detection and electrochemical signal detection within different detection limits. Therefore, Fe/GOx microgel provides a new platform and catalyst for the precise detection of cascade catalysis.

Approaches to Improving the Selectivity of Nanozymes

Nanozymes mimic enzymes and that includes their selectivity. To achieve selectivity, significant inspiration for nanoparticle design can come from the geometric and molecular features that make enzymes selective catalysts. The two central features enzymes use are control over the arrangement of atoms in the active site and the placing of the active site down a nanoconfined substrate channel. The implementation of enzyme-inspired features has already been shown to both improve activity and selectivity of nanoparticles for a variety of catalytic and sensing applications. The tuning and control of active sites on metal nanoparticle surfaces ranges from simply changing the composition of the surface metal to sophisticated approaches such as the immobilization of single atoms on a metal substrate. Molecular frameworks provide a powerful platform for the implementation of isolated and discrete active sites while unique diffusional environments further improve selectivity. The implementation of nanoconfined substrate channels around these highly controlled active sites offers further ability to control selectivity through altering the solution environment and transport of reactants and products. Implementing these strategies together offers a unique opportunity to improve nanozyme selectivity in both sensing and catalysis.

Cascade Dual Sites Modulate Local CO Coverage and Hydrogen-Binding Strength to Boost CO2 Electroreduction to Ethylene

Rationally modulating the binding strength of reaction intermediates on surface sites of copper-based catalysts could facilitate C-C coupling to generate multicarbon products in an electrochemical CO2 reduction reaction. Herein, theoretical calculations reveal that cascade Ag-Cu dual sites could synergistically increase local CO coverage and lower the kinetic barrier for CO protonation, leading to enhanced asymmetric C-C coupling to generate C2H4. As a proof of concept, the Cu3N-Ag nanocubes (NCs) with Ag located in partial Cu sites and a Cu3N unit center are successfully synthesized. The Faraday efficiency and partial current density of C2H4 over Cu3N-Ag NCs are 7.8 and 9.0 times those of Cu3N NCs, respectively. In situ spectroscopies combined with theoretical calculations confirm that Ag sites produce CO and Cu sites promote asymmetric C-C coupling to *COCHO, significantly enhancing the generation of C2H4. Our work provides new insights into the cascade catalysis strategy at the atomic scale for boosting CO2 to multicarbon products.

Self-Driven Electric Field Control of Orbital Electrons in AuPd Alloy Nanoparticles for Cancer Catalytic Therapy

The free radical generation efficiency of nanozymes in cancer therapy is crucial, but current methods fall short. Alloy nanoparticles (ANs) hold promise for improving catalytic performance due to their inherent electronic effect, but there are limited ways to modulate this effect. Here, a self-driven electric field (E) system utilizing triboelectric nanogenerator (TENG) and AuPd ANs with glucose oxidase (GOx)-like, catalase (CAT)-like, and peroxidase (POD)-like activities is presented to enhance the treatment of 4T1 breast cancer in mice. The E stimulation from TENG enhances the orbital electrons of AuPd ANs, resulting in increased CAT-like, GOx-like, and POD-like activities. Meanwhile, the catalytic cascade reaction of AuPd ANs is further amplified after catalyzing the production of H2 O2 from the GOx-like activities. This leads to 89.5% tumor inhibition after treatment. The self-driven E strategy offers a new way to enhance electronic effects and improve cascade catalytic therapeutic performance of AuPd ANs in cancer therapy.

Cu-based catalyst designs in CO2 electroreduction: precise modulation of reaction intermediates for high-value chemical generation

The massive emission of excess greenhouse gases (mainly CO2) have an irreversible impact on the Earth's ecology. Electrocatalytic CO2 reduction (ECR), a technique that utilizes renewable energy sources to create highly reduced chemicals (e.g. C2H4, C2H5OH), has attracted significant attention in the science community. Cu-based catalysts have emerged as promising candidates for ECR, particularly in producing multi-carbon products that hold substantial value in modern industries. The formation of multi-carbon products involves a range of transient intermediates, the behaviour of which critically influences the reaction pathway and product distribution. Consequently, achieving desirable products necessitates precise regulation of these intermediates. This review explores state-of-the-art designs of Cu-based catalysts, classified into three categories based on the different prospects of the intermediates' modulation: heteroatom doping, morphological structure engineering, and local catalytic environment engineering. These catalyst designs enable efficient multi-carbon generation in ECR by effectively modulating reaction intermediates.

Ag-Co3 O4 -CoOOH-Nanowires Tandem Catalyst for Efficient Electrocatalytic Conversion of Nitrate to Ammonia at Low Overpotential via Triple Reactions

The electrocatalytic conversion of nitrate (NO3 ‾) to NH3  (NO3 RR) offers a promising alternative to the Haber-Bosch process. However, the overall kinetic rate of NO3 RR is plagued by the complex proton-assisted multiple-electron transfer process. Herein, Ag/Co3 O4 /CoOOH nanowires (i-Ag/Co3 O4  NWs) tandem catalyst is designed to optimize the kinetic rate of intermediate reaction for NO3 RR simultaneously. The authors proved that NO3 ‾ ions are reduced to NO2 ‾ preferentially on Ag phases and then NO2 ‾ to NO on Co3 O4  phases. The CoOOH phases catalyze NO reduction to NH3  via NH2 OH intermediate. This unique catalyst efficiently converts NO3 ‾ to NH3  through a triple reaction with a high Faradaic efficiency (FE) of 94.3% and a high NH3  yield rate of 253.7 μmol h-1  cm-2  in 1 M KOH and 0.1 M KNO3  solution at -0.25 V versus RHE. The kinetic studies demonstrate that converting NH2 OH into NH3  is the rate-determining step (RDS) with an energy barrier of 0.151 eV over i-Ag/Co3 O4  NWs. Further applying i-Ag/Co3 O4  NWs as the cathode material, a novel Zn-nitrate battery exhibits a power density of 2.56 mW cm-2  and an FE of 91.4% for NH3  production.

Atomic high-spin cobalt(II) center for highly selective electrochemical CO reduction to CH3OH

In this work, via engineering the conformation of cobalt active center in cobalt phthalocyanine molecular catalyst, the catalytic efficiency of electrochemical carbon monoxide reduction to methanol can be dramatically tuned. Based on a collection of experimental investigations and density functional theory calculations, it reveals that the electron rearrangement of the Co 3d orbitals of cobalt phthalocyanine from the low-spin state (S = 1/2) to the high-spin state (S = 3/2), induced by molecular conformation change, is responsible for the greatly enhanced CO reduction reaction performance. Operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy measurements disclose accelerated hydrogenation of CORR intermediates, and kinetic isotope effect validates expedited proton-feeding rate over cobalt phthalocyanine with high-spin state. Further natural population analysis and density functional theory calculations demonstrate that the high spin Co2+ can enhance the electron backdonation via the dxz/dyz-2π* bond and weaken the C-O bonding in *CO, promoting hydrogenation of CORR intermediates.

A comprehensive exploration of the latest innovations for advancements in enhancing selectivity of nanozymes for theranostic nanoplatforms

Nanozymes have captured significant attention as a versatile and promising alternative to natural enzymes in catalytic applications, with wide-ranging implications for both diagnosis and therapy. However, the limited selectivity exhibited by many nanozymes presents challenges to their efficacy in diagnosis and raises concerns regarding their impact on the progression of disease treatments. In this article, we explore the latest innovations aimed at enhancing the selectivity of nanozymes, thereby expanding their applications in theranostic nanoplatforms. We place paramount importance on the critical development of highly selective nanozymes and present innovative strategies that have yielded remarkable outcomes in augmenting selectivities. The strategies encompass enhancements in analyte selectivity by incorporating recognition units, refining activity selectivity through the meticulous control of structural and elemental composition, integrating synergistic materials, fabricating selective nanomaterials, and comprehensively fine-tuning selectivity via approaches such as surface modification, cascade nanozyme systems, and manipulation of external stimuli. Additionally, we propose optimized approaches to propel the further advancement of these tailored nanozymes while considering the limitations associated with existing techniques. Our ultimate objective is to present a comprehensive solution that effectively addresses the limitations attributed to non-selective nanozymes, thus unlocking the full potential of these catalytic systems in the realm of theranostics.

Cascade electrocatalysis via AgCu single-atom alloy and Ag nanoparticles in CO2 electroreduction toward multicarbon products

Electrocatalytic CO2 reduction into value-added multicarbon products offers a means to close the anthropogenic carbon cycle using renewable electricity. However, the unsatisfactory catalytic selectivity for multicarbon products severely hinders the practical application of this technology. In this paper, we report a cascade AgCu single-atom and nanoparticle electrocatalyst, in which Ag nanoparticles produce CO and AgCu single-atom alloys promote C-C coupling kinetics. As a result, a Faradaic efficiency (FE) of 94 ± 4% toward multicarbon products is achieved with the as-prepared AgCu single-atom and nanoparticle catalyst under ~720 mA cm-2 working current density at -0.65 V in a flow cell with alkaline electrolyte. Density functional theory calculations further demonstrate that the high multicarbon product selectivity results from cooperation between AgCu single-atom alloys and Ag nanoparticles, wherein the Ag single-atom doping of Cu nanoparticles increases the adsorption energy of *CO on Cu sites due to the asymmetric bonding of the Cu atom to the adjacent Ag atom with a compressive strain.

Single B-vacancy enriched α1-borophene sheet: an efficient metal-free electrocatalyst for CO2 reduction

By employing first principles calculations, we have studied the electronic structures of pristine (α1) and different defective (α1-t1, α1-t2) borophene sheets to understand the efficacy of such systems as metal-free electrocatalysts for the CO2 reduction reaction. Among the three studied systems, only α1-t1, the defective borophene sheet created by removal of a 5-coordinated boron atom, can chemisorb and activate a CO2 molecule for its subsequent reduction processes, leading to different C1 chemicals, followed by selective conversion into C2 products by multiple proton coupled electron transfer steps. The computed onset potentials for the C1 chemicals such as CH3OH and CH4 are low enough. On the other hand, in the case of the C2 reduction process, the C-C coupling barrier is only 0.80 eV in the solvent phase which produces CH3CHO and CH3CH2OH with very low onset potential values of -0.21 and -0.24 V, respectively, suppressing the competing hydrogen evolution reaction.

Nucleic acid-functionalized nanozymes and their applications

Nanozymes are inorganic, organic and metal-organic framework nanoparticles that reveal catalytic functions by emulating native enzyme activities. Recently, these nanozymes have attracted growing scientific interest, finding diverse analytical and medical applications. However, the catalytic activities and functions of nanozymes are limited, due to the lack of substrate binding sites that concentrate on the substrate at the catalytic site (molarity effect), introduce substrate specificity and allow functional complexity of the catalysts (cascaded, switchable and cooperative catalysis). The modification of nanozymes with functional nucleic acids provides means to overcome these limitations and engineer nucleic acid/nanozyme hybrids for diverse applications. This is exemplified with the synthesis of aptananozymes, which are supramolecular aptamer-modified nanozymes. Aptananozymes exhibit combined specific binding and catalytic properties that drive diverse chemical transformations, revealing enhanced catalytic activities, as compared to the separated nanozyme/aptamer constituents. Relationships of structure-catalytic functions in the aptananozyme constructs are demonstrated. In addition, modification of nanozymes exhibiting multimodal catalytic functions with aptamers allows the engineering of nanozyme-based bioreactors for cascaded catalysis. Also, the functionalization of reactive oxygen species (ROS)-generating nanozymes with cancer cell-recognizing aptamers yields aptananozymes for targeted chemodynamic treatment of cancer cells and cancer tumors elicited in mice. Finally, nucleic acid-modified enzyme (glucose oxidase)-loaded metal-organic framework nanoparticles yield switchable biocatalytic nanozymes that drive the ON/OFF biocatalyzed oxidation of Amplex Red, dopamine or the generation of chemiluminescence. Herein, future challenges of the topic are addressed.

An orientated mass transfer in Ni-Cu tandem nanofibers for highly selective reduction of CO2 to ethanol

Electrochemically reducing CO2 to ethanol is attractive but suffers from poor selectivity. Tandem catalysis that integrates the activation of CO2 to an intermediate using one active site and the subsequent formation of hydrocarbons on the other site offers a promising approach, where the control of the intermediate transfer between different catalytic sites is challenging. We propose an internally self-feeding mechanism that relies on the orientation of the mass transfer in a hierarchical structure and demonstrate it using a one-dimensional (1D) tandem core-shell catalyst. Specifically, the carbon-coated Ni-core (Ni/C) catalyzes the transformation of CO2-to-CO, after which the CO intermediates are guided to diffuse to the carbon-coated Cu-shell (Cu/C) and experience the selective reduction to ethanol, realizing the orientated key intermediate transfer. Results show that the Faradaic efficiency for ethanol was 18.2% at -1 V vs. RHE (VRHE) for up to 100 h. The following mechanism study supports the hypothesis that the CO2 reduction on Ni/C generates CO, which is further reduced to ethanol on Cu/C sites. Density functional theory calculations suggest a combined effect of the availability of CO intermediate in Ni/C core and the dimerization of key *CO intermediates, as well as the subsequent proton-electron transfer process on the Cu/C shell.

Pb-rich Cu grain boundary sites for selective CO-to-n-propanol electroconversion

Electrochemical carbon monoxide (CO) reduction to high-energy-density fuels provides a potential way for chemical production and intermittent energy storage. As a valuable C3 species, n-propanol still suffers from a relatively low Faradaic efficiency (FE), sluggish conversion rate and poor stability. Herein, we introduce an "atomic size misfit" strategy to modulate active sites, and report a facile synthesis of a Pb-doped Cu catalyst with numerous atomic Pb-concentrated grain boundaries. Operando spectroscopy studies demonstrate that these Pb-rich Cu-grain boundary sites exhibit stable low coordination and can achieve a stronger CO adsorption for a higher surface CO coverage. Using this Pb-Cu catalyst, we achieve a CO-to-n-propanol FE (FEpropanol) of 47 ± 3% and a half-cell energy conversion efficiency (EE) of 25% in a flow cell. When applied in a membrane electrode assembly (MEA) device, a stable FEpropanol above 30% and the corresponding full-cell EE of over 16% are maintained for over 100 h with the n-propanol partial current above 300 mA (5 cm2 electrode). Furthermore, operando X-ray absorption spectroscopy and theoretical studies reveal that the structurally-flexible Pb-Cu surface can adaptively stabilize the key intermediates, which strengthens the *CO binding while maintaining the C-C coupling ability, thus promoting the CO-to-n-propanol conversion.

Theoretical Study of the Defects and Doping in Tuning the Electrocatalytic Activity of Graphene for CO2 Reduction

The application of graphene-based catalysts in the electrocatalytic CO2 reduction reaction (ECO2RR) for mitigating the greenhouse effect and energy shortage is a growing trend. The unique and extraordinary properties of graphene-based catalysts, such as low cost, high electrical conductivity, structural tunability, and environmental friendliness, have rendered them promising materials in this area. By doping heteroatoms or artificially inducing defects in graphene, its catalytic performance can be effectively improved. In this work, the mechanisms underlying the CO2 reduction reaction on 10 graphene-based catalysts were systematically studied. N/B/O-codoped graphene with a single-atom vacancy defect showed the best performance and substantial improvement in catalytic activity compared with pristine graphene. The specific roles of the doped elements, including B, N, and O, as well as the defects, are discussed in detail. By analysing the geometric and electronic structures of the catalysts, we showed how the doped heteroatoms and defects influence the catalytic reaction process and synergistically promoted the catalytic efficiency of graphene.

Chemical and Structural Evolution of AgCu Catalysts in Electrochemical CO2 Reduction

Silver-copper (AgCu) bimetallic catalysts hold great potential for electrochemical carbon dioxide reduction reaction (CO₂RR), which is a promising way to realize the goal of carbon neutrality. Although a wide variety of AgCu catalysts have been developed so far, it is relatively less explored how these AgCu catalysts evolve during CO₂RR. The absence of insights into their stability makes the dynamic catalytic sites elusive and hampers the design of AgCu catalysts in a rational manner. Here, we synthesized intermixed and phase-separated AgCu nanoparticles on carbon paper electrodes and investigated their evolution behavior in CO₂RR. Our time-sequential electron microscopy and elemental mapping studies show that Cu possesses high mobility in AgCu under CO₂RR conditions, which can leach out from the catalysts by migrating to the bimetallic catalyst surface, detaching from the catalysts, and agglomerating as new particles. Besides, Ag and Cu manifest a trend to phase-separate into Cu-rich and Ag-rich grains, regardless of the starting catalyst structure. The composition of the Cu-rich and Ag-rich grains diverges during the reaction and eventually approaches thermodynamic values, i.e., Ag_0.88Cu_0.12 and Ag_0.05Cu_0.95. The separation between Ag and Cu has been observed in the bulk and on the surface of the catalysts, highlighting the importance of AgCu phase boundaries for CO₂RR. In addition, an operando high-energy-resolution X-ray absorption spectroscopy study confirms the metallic state of Cu in AgCu as the catalytically active sites during CO₂RR. Taken together, this work provides a comprehensive understanding of the chemical and structural evolution behavior of AgCu catalysts in CO₂RR.

Rational design of trimetallic AgPt-Fe3O4 nanozyme for catalyst poisoning-mediated CO colorimetric detection

Carbon monoxide (CO) is not only a highly poisonous gas that brings great health risk, but also a significant signaling molecule in body. However, it is still challengeable for development of alternative colorimetric probes to traditional organic chromophores for simple, sensitive and convenient CO sensing. Here, for the first time, we rationally design a novel hydrophilic AgPt-Fe₃O₄ nanozyme with a unique heterodimeric nanostructure for colorimetric sensing of CO based on the excellent peroxidase-like catalytic activity as well as highly poisonous effect of CO on the nanozyme's catalytic activity. Both experimental evidence and theoretical calculations reveal the trimetallic AgPt-Fe₃O₄ nanozyme is susceptible to poisoning with the strongest affinity towards CO compared to individual Fe₃O₄ or Ag-Fe₃O₄, which is attributed to the adequate exposure of the active metallic sites and efficient interfacial synergy of unique heterodimeric nanostructure. Accordingly, a novel nanozyme-based colorimetric strategy is developed for CO detection with a low detection limit of 5.6 ppb in solution. Furthermore, the probe can be prepared as very convenient test strips and integrated with the portable smartphone platforms for detecting CO gas samples with a low detection limit of 8.9 ppm. Overall, our work proposes guidelines for the rational design of metallic heterogeneous nanostructure to expand the analytical application of nanozyme.

Recent Advances of Core-Shell Cu-Based Catalysts for the Reduction of CO2 to C2+ Products

Copper is a key metal for carbon dioxide (CO₂ ) reduction reaction, which can reduce CO₂ to value-added products. The core-shell structure can effectively promote the C-C coupling process due to its strong synergistic effect originated from its unique electronic structure and interface environment. Therefore, the combination of copper and core-shell structure to design an efficient Cu-based core-shell structure catalyst is of great significance for electrocatalytic CO₂ reduction (CO₂ RR). In this review, we first briefly summarize the basic principle of CO₂ RR. In addition, we outline the advantages of core-shell structure for catalysis. Then, we review the recent research progresses of Cu-based core-shell structures for the selective reduction of multi-carbon (C₂₊ ) products. In the end, the challenges of using core-shell catalyst for CO₂ RR are described, and the future development of this field is prospected.

Single-entity Electrochemistry Unveils Dynamic Transformation during Tandem Catalysis of Cu2 O and Co3 O4 for Converting NO3 - to NH3

Electrochemically converting nitrate to ammonia is an essential and sustainable approach to restoring the globally perturbed nitrogen cycle. The rational design of catalysts for the nitrate reduction reaction (NO₃ RR) based on a detailed understanding of the reaction mechanism is of high significance. We report a Cu₂ O+Co₃ O₄ tandem catalyst which enhances the NH₃ production rate by ≈2.7-fold compared to Co₃ O₄ and ≈7.5-fold compared with Cu₂ O, respectively, however, most importantly, we precisely place single Cu₂ O and Co₃ O₄ cube-shaped nanoparticles individually and together on carbon nanoelectrodes provide insight into the mechanism of the tandem catalysis. The structural and phase evolution of the individual Cu₂ O+Co₃ O₄ nanocubes during NO₃ RR is unveiled using identical location transmission electron microscopy. Combining single-entity electrochemistry with precise nano-placement sheds light on the dynamic transformation of single catalyst particles during tandem catalysis in a direct way.

The spatial distribution of cobalt phthalocyanine and copper nanocubes controls the selectivity towards C2 products in tandem electrocatalytic CO2 reduction

The coupling of CO-generating molecular catalysts with copper electrodes in tandem schemes is a promising strategy to boost the formation of multi-carbon products in the electrocatalytic reduction of CO₂. While the spatial distribution of the two components is important, this aspect remains underexplored for molecular-based tandem systems. Herein, we address this knowledge gap by studying tandem catalysts comprising Co-phthalocyanine (CoPc) and Cu nanocubes (Cu_cub). In particular, we identify the importance of the relative spatial distribution of the two components on the performance of the tandem catalyst by preparing CoPc-Cu_cub/C, wherein the CoPc and Cu_cub share an interface, and CoPc-C/Cu_cub, wherein the CoPc is loaded first on carbon black (C) before mixing with the Cu_cub. The electrocatalytic measurements of these two catalysts show that the faradaic efficiency towards C₂ products almost doubles for the CoPc-Cu_cub/C, whereas it decreases by half for the CoPc-C/Cu_cub, compared to the Cu_cub/C. Our results highlight the importance of a direct contact between the CO-generating molecular catalyst and the Cu to promote C-C coupling, which hints at a surface transport mechanism of the CO intermediate between the two components of the tandem catalyst instead of a transfer via CO diffusion in the electrolyte followed by re-adsorption.

Recent Advances of the Confinement Effects Boosting Electrochemical CO2 Reduction

Powered by clean and renewable energy, electrocatalytic CO₂ reduction reaction (CO₂ RR) to chemical feedstocks is an effective way to mitigate the greenhouse effect and artificially close the carbon cycle. However, the performance of electrocatalytic CO₂ RR was impeded by the strong thermodynamic stability of CO₂ molecules and the high susceptibility to hydrogen evolution reaction (HER) in aqueous phase systems. Moreover, the numerous reaction intermediates formed at very near potentials lead to poor selectivity of reaction products, further preventing the industrialization of CO₂ RR. Catalysis in confined space can enrich the reaction intermediates to improve their coverage at the active site, increase local pH to inhibit HER, and accelerate the mass transfer rate of reactants/products and subsequently facilitate CO₂ RR performance. Therefore, we summarize the research progress on the application of the confinement effects in the direction of CO₂ RR in theoretical and experimental directions. We first analyzed the mechanism of the confinement effect. Subsequently, the confinement effect was discussed in various forms, which can be characterized as an abnormal catalytic phenomenon due to the relative limitation of the reaction region. In specific, based on the physical structure of the catalyst, the confinement effect was divided in four categories: pore structure confinement, cavity structure confinement, active center confinement, and other confinement methods. Based on these discussions, we also have summarized the prospects and challenges in this field. This review aims to stimulate greater interests for the development of more efficient confined strategy for CO₂ RR in the future.

Nanoconfinement Allows a Less Active Cascade Catalyst to Produce More C2+ Products in Electrochemical CO2 Reduction

Enzymes with multiple distinct active sites linked by substrate channels combined with control over the solution environment near the active sites enable the formation of complex products from simple reactants via the confinement of intermediates. We mimic this concept to facilitate the electrochemical carbon dioxide reduction reaction using nanoparticles with a core that produces intermediate CO at different rates and a porous copper shell. CO₂ reacts at the core to produce CO which then diffuses through the Cu to give higher order hydrocarbon molecules. By altering the rate of CO₂ delivery, the activity of the CO producing site, and the applied potential, we show that the nanoparticle with lower activity for CO formation produces greater amounts of hydrocarbon products. This is attributed to a combination of higher local pH and the lower amount of CO, resulting in more stable nanoparticles. However, when lower amounts of CO₂ were delivered to the core, the particles that are more active for CO formation produce more C₃ products. The importance of these results is twofold. They show that in cascade reactions, more active intermediate producing catalysts do not necessarily give greater amounts of high-value products. The effect an intermediate producing active site has on the local solution environment around the secondary active site plays an important role. As the less active catalyst for producing CO also possesses greater stability, we show that nanoconfinement can be used to get the best of both worlds with regard to having a stable catalyst with high activity.

Mesoporous PdN Alloy Nanocubes for Efficient Electrochemical Nitrate Reduction to Ammonia

Developing highly active and selective electrocatalysts for electrochemical nitrate reduction reaction (NITRR) is very important for synthesizing recyclable ammonia (NH₃ ) in an economic and environmentally friendly manner. Despite some encouraging progress, their activity and selectivity have been remarkably slower than expected. In this manuscript, mesoporous palladium-nonmetal (meso-PdX) nanocubes (NCs) are reported as a new series of highly efficient electrocatalysts for selective nitrate reduction reaction (NITRR) electrocatalysis to NH₃ . The samples feature uniformly alloyed compositions and highly penetrated mesopores with abundant highly active sites and optimized electronic structures. The best meso-PdN NCs hold an outstanding NITRR activity and selectivity with a remarkable NH₃ Faradaic efficiency of 96.1% and a yield rate of 3760 µg h^-1 mg^-1 , suppressing the state-of-the-art electrocatalysts. Meanwhile, meso-PdN NCs are electrocatalytically stable, retaining well the activity and selectivity of NO₃ ^- -to-NH₃ electrocatalysis for more than 20 cycles. Detailed mechanism studies ascribe the superior performance to combined compositional and structural synergies of meso-PdN NCs that not only promote the adsorption (reactivity) of NO₃ ^- and the desorption of NH₃ but also increase the retention time of key intermediates for the deeper NITRR electrocatalysis to NH₃ through an eight-electron pathway.

Aptamer-Functionalized Ce4+-Ion-Modified C-Dots: Peroxidase Mimicking Aptananozymes for the Oxidation of Dopamine and Cytotoxic Effects toward Cancer Cells

Aptamer-functionalized Ce⁴⁺-ion-modified C-dots act as catalytic hybrid systems, aptananozymes, catalyzing the H₂O₂ oxidation of dopamine. A series of aptananozymes functionalized with different configurations of the dopamine binding aptamer, DBA, are introduced. All aptananozymes reveal substantially enhanced catalytic activities as compared to the separated Ce⁴⁺-ion-modified C-dots and aptamer constituents, and structure-catalytic functions between the structure and binding modes of the aptamers linked to the C-dots are demonstrated. The enhanced catalytic functions of the aptananozymes are attributed to the aptamer-induced concentration of the reaction substrates in spatial proximity to the Ce⁴⁺-ion-modified C-dots catalytic sites. The oxidation processes driven by the Ce⁴⁺-ion-modified C-dots involve the formation of reactive oxygen species (^•OH radicals). Accordingly, Ce⁴⁺-ion-modified C-dots with the AS1411 aptamer or MUC1 aptamer, recognizing specific biomarkers associated with cancer cells, are employed as targeted catalytic agents for chemodynamic treatment of cancer cells. Treatment of MDA-MB-231 breast cancer cells and MCF-10A epithelial breast cells, as control, with the AS1411 aptamer- or MUC1 aptamer-modified Ce⁴⁺-ion-modified C-dots reveals selective cytotoxicity toward the cancer cells. In vivo experiments reveal that the aptamer-functionalized nanoparticles inhibit MDA-MB-231 tumor growth.