Boosted C-C coupling with Cu-Ag alloy sub-nanoclusters for CO2-to-C2H4 photosynthesis

Synergistic integration of bimetallic PtCu alloy modulating proton supply for efficient artificial photosynthesis of methanol

Photocatalytic CO2 reduction with H2O into valuable solar fuels is a huge potential to alleviate carbon emissions and energy issues. However, selective photocatalytic CO2 reduction with H2O into desired chemicals is still a grand challenge owing to the unfavorable kinetics of multistep proton-coupled electrons. Herein, we employed a facile photo-deposition strategy to load Pt-Cu alloy over BiOBr1-xClx (BOBC) for CO2 photoreduction with H2O as a proton donor. The optimal Pt-Cu/BOBC with Pt-Cu pair sites exhibited a remarkable performance of CO2 photoreduction yielding CH3OH of 16.52 μmol·g-1·h-1 with 97.14 % electron-based selectivity. The experimental and theoretical analysis revealed the synergistic effect of Pt-Cu pair sites in BOBC, which enabled Pt to promote the formation of protons from dissociated H2O while Cu accelerate the protonation of CO2, thus advancing the highly selective production of CH3OH. This work highlighted the role of proton supply from H2O oxidation to promote the kinetics of CO2 protonation during photocatalytic reaction.

Switching CO2 reduction selectivity in Cu-TiO2 catalysts: Role of Cu+ site location and oxygen vacancy concentration

Efficient conversion of CO2 into valuable chemicals such as CH4 under mild conditions is a significant challenge due to the high thermodynamic and kinetic barriers associated with multi-electron transfer reactions. In this study, we present a microwave-assisted strategy for the synthesis of Cu-doped, oxygen vacancy (Ov)-enriched TiO2 nanotubes (C-CT) that stabilize both bulk and surface Cu+ species. These photocatalysts exhibit a remarkable CH4 production rate of 202.1 μmol g-1 h-1 under simulated sunlight, with an outstanding electron selectivity of 99 %. Mechanistic investigations reveal that the synergistic interaction between Cu+ sites and oxygen vacancies enhances charge separation, stabilizes critical reaction intermediates, and facilitates the eight-electron reduction pathway for selective CH4 production. This work offers a sustainable approach to CO2 utilization, helping to overcome the thermodynamic and kinetic barriers in CO2 photoreduction. Such efficient photocatalysts have the potential to significantly reduce CO2 emissions and promote environmental sustainability.

Interfacial Metal Oxides Stabilize Cu Oxidation States for Electrocatalytical CO2 Reduction

Modulating the oxidation state of copper (Cu) is crucial for enhancing the electrocatalytic CO2 reduction reaction (CO2RR), particularly for facilitating deep reductions to produce methane (CH4) or multi-carbon (C2+) products. However, Cuδ+ sites are thermodynamically unstable, fluctuating their oxidation states under reaction conditions, which complicates their functionality. Incorporating interfacial metal oxides has emerged as an effective strategy for stabilizing these oxidation states. This review provides an in-depth examination of the reaction mechanisms occurring at oxide-modified Cuδ+ sites, offering a comprehensive understanding of their behavior. We explore how Cu/metal oxide interfaces stabilize Cu oxidation states, showing that oxides-modified Cu catalysts often enhance selectivity for C2+ or CH4 products by stabilizing Cu+ or Cu2+ sites. In addition, we discuss innovative strategies for the rational design of efficient Cu catalytic sites tailored for specific deep CO2RR products. The review concludes with an outlook on current challenges and future directions, offering new insights into the rational design of selective and efficient CO2RR catalysts.

High-Loading Cu Single-Atom Engineering on g-C₃N₄ for Visible-Light CO₂ Photoreduction

The incorporation of metal single atoms into carbon nitride (CN) has emerged as a promising strategy for photocatalytic CO₂ reduction under visible light. However, achieving high single-atom loading and unraveling the precise role of active metal centers in CO₂ conversion remain formidable challenges. Herein, an ultrasound-assisted coordination exchange strategy is reported that enables the high-loading of Cu single atoms on CN. X-ray absorption near-edge spectroscopy and aberration-corrected electron microscopy confirm that Cu is atomically dispersed and coordinated with nitrogen. The introduction of Cu single atoms modulates the electronic structure of CN, serving as electron accumulation centers that facilitate charge carrier separation and transfer. Theoretical calculations combined with in situ spectroscopic analyses reveal that Cu single atoms act as active sites, enhancing CO₂ adsorption and activation while significantly reducing the energy barrier for *COOH formation, thereby optimizing reaction thermodynamics. As a result, under visible-light irradiation, Cu-modified CN achieves a CO production rate of 14.65 µmol g⁻¹ h⁻¹, representing an 11.3-fold enhancement over pristine CN. This work not only establishes an efficient approach for synthesizing high-loading single-atom catalysts but also provides fundamental insights into the mechanistic role of single-atom sites in photocatalytic CO₂ reduction.

Chemical microenvironment regulation of single-atom catalysts in photocatalysis

The emerging single-atom catalysts (SACs) have garnered significant attention in photocatalytic energy conversion processes due to their high atomic efficiency and unique structural characteristics. The geometric structure and electronic properties of SACs are primarily governed by their chemical microenvironment, which almost entirely determines their photocatalytic performance. Herein, we highlight the recent advances in the microenvironment engineering of SACs, focusing on the regulation of coordinating atoms and metal center sites. Moreover, we summarize the achievements in microenvironment modulation across various photocatalytic applications, including CO2 reduction, CH4 conversion, N2 fixation, H2O splitting and pollutant degradation. The fundamental impacts of SACs' microenvironment on photocatalytic activity, selectivity, and stability are further explored. Finally, we summarize the challenges in the development of microenvironment engineering and provide an outlook on future opportunities and challenges. This comprehensive review offers guidance for the design and fabrication of highly active SACs and is expected to foster the progress of microenvironment engineering.

Synergistical Catalysis of TiO2 and SAPO-34 for Efficient Conversion of CO2 to C2H4

The excessive emission of carbon dioxide (CO2) into the atmosphere has led to a significant global warming crisis. Utilizing bifunctional catalysts, which consist of bimetallic oxides and SAPO-34, for catalyzing the conversion of CO2 to high-value-added ethylene (C2H4) can effectively mitigate this issue. However, this process also produces a substantial number of by-products. Additionally, the use of bimetallics or precious metals increases the catalyst costs. In this study, we propose an innovative synergistic approach by integrating SAPO-34 with TiO2, enabling both efficient CO2 capture and its catalytic conversion into C2 hydrocarbons. The system achieved a C2H4 yield of 20 μmol g-1 with a selectivity of 63.5%. Comprehensive characterizations revealed that the 30% TiO2/SAPO composite exhibited a higher concentration of oxygen vacancies and a greater percentage of Ti3+ species. Moreover, the confinement effect of SAPO-34 facilitated the C-C coupling and the formation of C2H4. This work exemplifies a dual-functional strategy, providing valuable insights for carbon reduction.

Visualizing the dynamic evolution of light-sensitive Cu1+/Cu2+ sites during photocatalytic CO2 reduction with an advanced in situ EPR spectroscopy

Elucidation of the dynamic evolution of active sites is still a challenge in investigating the catalytic mechanism mainly due to the difficulty in accurately detecting the transient structural changes of active sites under operating conditions. Here, we develop an advanced in situ electron paramagnetic resonance (EPR) spectroscopy, which could sensitively monitor and visualize the dynamic evolution of paramagnetic active sites during photoreduction CO2. In situ results reveal that the photoactivated Cu1+ sites from CuO nanoclusters/TiO2 serve as the authentic active sites in the reaction and exhibit self-regenerative capability. The CO2 molecules can acquire electrons and get activated by the photoactivated Cu1+, leading to the transition of Cu1+ sites into Cu2+ sites. Subsequently, the Cu2+ sites expedite the generation of hydrogen protons through antiferromagnetic coupling with hydroxyl radicals, thereby promoting the production of the final product CH4 via a multi proton-coupled electron transfer (PCET) process. This work reveals and visualizes the dynamic evolution of Cu-based active sites during photocatalytic reactions by combined in situ characterizations, providing new perspectives on the mechanistic understanding of paramagnetic active sites under operation.

Pt single atoms promoting the construction of asymmetric double sites to achieve highly selective photoreduction of CO2 to ethylene

In this work, Pt single atoms (SAs) were engineered on the surface of CdIn2S4 (CIS) to trigger abundant generation and stable existence of sulfur vacancies (Sv). Through quasi in situ X-ray photoelectron spectroscopy (XPS) and work function analysis, the photogenerated electrons are first captured by Pt SAs and Sv, and then transferred from Pt SAs to Sv, ultimately increasing the electron density of Sv. Meanwhile, Sv have significant advantages in adsorbing CO2 molecules. According to the number of transferred electrons, the optimized 0.8 %Pt/CIS has 76 times the photocatalytic performance of pristine CIS, and the selectivity of ethylene (C2H4) is up to 99.3 %. The carbon-carbon coupling reaction between *CO and *CHO adsorbed on double sites of Sv and In atoms is identified as the rate-determining step. Theoretical calculations suggest that the energy barrier required for coupling of intermediates *CO and *CHO is the lowest, conducive to the selective generation of C2H4.

Ultrahigh Sensing Performance: Coresponse and Differentiation of Ethyl Acetate and Its Byproducts in Fe-Ce-O Interfacial Sensor

Accurately detecting low concentrations of ethyl acetate (EA) holds promise for the early screening of rectal and gastric cancer. The primary challenges lie in achieving a high response at parts per billion level concentration and ensuring high selectivity. This study focuses on designing Fe-Ce-O bimetallic oxides with doping and heterogeneous interfaces, which exhibit outstanding redox properties and highly enhanced ability of the adsorption and activation of both O2 and EA molecules. Benefiting from the violent reaction between EA and the adsorbed oxygen species, the sensor achieves an ultrahigh ethyl acetate sensing response of more than 500,000 at 200 ppm concentration, along with an ultrafast recovery rate (<5 s). In experiments, the response can reach 4.8 even at an extremely low concentration of 10 ppb. Special attention is given to the interfacial chemical reactions through in situ DRIFTS during the sensing process. We propose for the first time that the produced intermediate byproducts (acetaldehyde, ethyl alcohol, acetic acid, and formic acid) coresponse on this sensor, contributing to its ultrahigh sensing response. Furthermore, both EA and the byproducts are effectively classified using linear discriminant analysis with 95% accuracy. This work is expected to elucidate the interfacial sensing mechanisms, particularly the contributions of derived byproducts to the sensor's response, and to propose a novel idea for designing high-performance sensors.

High-Efficiency Photooxidation of Methane to the C1 Product

The efficient conversion of methane (CH4) to high-value-added chemicals using a photocatalyst at room temperature and pressure faces great challenges compared to harsh reaction conditions. However, achieving this efficient conversion would yield substantial cost advantages and hold immense potential for development. Here, we demonstrate the enhanced photocatalytic conversion efficiency of CH4 at room temperature and pressure conditions without requiring any oxidant through the construction of a bimetal Ag-Cu-loaded brookite TiO2 photocatalyst. The C1 products were ultimately obtained with 100% selectivity and a yield of 936 μmol·g-1·h-1. The performance exceeds that of similar research by tens of times. The high selectivity of this system is attributed to the optimal number of ·OH, which strikes a balance between excess and deficiency. Ag effectively enhances electron transport in the photocatalytic reaction process on a dual active site photocatalyst, while Cu significantly improves the selectivity of the C1 products. In this system, the hydroxyl radical (·OH) activates CH4 to generate the methyl radical (·CH3), which then binds with the lattice oxygen of TiO2, breaking the Ti-O bond and resulting in the formation of *OCH3. The *OCH3 undergoes further conversion to CH3OH, which is subsequently oxidized to HCHO by ·OH. This work presents a cost-effective and highly efficient approach for directly oxidizing CH4 into valuable chemicals, ensuring superior selectivity.

Selective Liquid Chemical Production in Waste Polyolefin Photorefinery by Controlling Reactive Species

Photocatalytic upcycling of waste polyolefins into value-added chemicals provides promise in plastic waste management and resource utilization. Previous works demonstrate that polyolefins can be converted into carboxylic acids, with CO2 as the final oxidation product. It is still challenging to explore more transformation products, particularly mild-oxidation products such as alcohols, because of their instability compared with polymer substrates, which are prone to oxidation during catalytic reactions. In this work, we propose an efficient strategy to regulate the product type through precise control of radicals, intermediates, and reaction paths. Taking the commonly used photocatalyst C3N4 as an example, its major products are carboxylic acids and CO2. When MoS2 is introduced to construct a Z-scheme heterostructure, gas products are significantly reduced and alcohols appear with a high yield of 1358.8 μmol gcat-1 and a high selectivity up to 80.3%. This is primarily attributed to the presence of •OH radicals from oxygen reduction, acting a key role in alcohol formation while simultaneously suppressing the competing pathways oxygen to •O2- and 1O2, thus reducing the overoxidation products. The β-scission of the C-C bonds in the polymer chains generates intermediate alkyl species, followed by the combination with •OH to produce methanol, which is more energetically favorable for MoS2/C3N4. In contrast, alkyl species couple with oxygen species to form formic acid, which is favorable for C3N4. This work provides new approaches for controlling the product types and offers new insights into the reaction pathways involved in polyolefin photorefinery.

Construction of ternary heterojunction photocatalyst Cu2Cl(OH)3/In/In2O3 for boosted photocatalytic CO2 reduction performance

The photocatalytic conversion of CO2 and H2O into useful chemicals or fuels over semiconductor photocatalysts is regarded as a promising technology to address the problems of global warming and energy exhaustion. However, inefficient photo-absorption and slow charge dynamics limit the CO2 photoreduction efficiency. Here, a ternary heterojunction photocatalyst, Cu2Cl(OH)3/In/In2O3 (Cu H IO), with an intimate interface is obtained via a hydrogen chemical reduction approach followed by hydrolysis reaction, where In species can be produced on the surface of In2O3 from the hydrogen chemical reaction with a calcining temperature of over 500 °C. Cu H IO exhibits enhanced photocatalytic activity for CO2 conversion compared to pristine In2O3, In2O3 with In species (H IO), and Cu2Cl(OH)3/In2O3 (Cu IO). In the absence of sacrificial agent or cocatalyst, the yield rates of CO and CH4 over Cu H IO are 4.36 and 1.09 μmol g-1 h-1, which are 8.38-fold and 18-fold that of pristine In2O3 (0.52 and 0.06 μmol g-1 h-1), respectively. The photocatalytic performance enhancement of Cu H IO results from the construction of the ternary heterojunction, with synchronous improvement in the photoresponse and charge separation of In2O3. Moreover, the possible CO2 reduction pathway over Cu H IO has also been investigated and proposed. This work provides an important strategy for developing a high-efficiency heterojunction photocatalyst system for solar fuel generation.

Metal-organic framework-derived silver/copper-oxide catalyst for boosting the productivity of carbon dioxide electrocatalysis to ethylene

Electrochemical reduction of CO2 into valuable multi-carbon (C2) chemicals holds promise for mitigating CO2 emissions and enabling artificial carbon cycling. However, achieving high selectivity remains challenging due to the limited activity and active sites of CC coupling catalysts. Herein, we report an Ag-modified Cu-oxide catalyst (CuO/Ag@C) derived from metal-organic frameworks (MOF), capable of efficiently converting CO2 to C2H4. The MOF-derived porous carbon confines the size of metal nanoparticles, ensuring sufficient exposure of active sites. Remarkably, the CuO/Ag@C catalyst achieves an impressive Faradaic efficiency of 48.6% for C2H4 at -0.7 V vs. RHE, demonstrating excellent stability. Both experimental results and theoretical calculations indicate that Ag sites promote the production of CO, enhancing the coverage of *CO on Cu sites. Furthermore, the reconfiguration of charge density at the Cu-Ag interface optimizes the electronic states of the reaction sites, reducing the formation energy of the key intermediate *OCCHO, thereby favoring C2H4 production effectively. This work provides insight into structurally rational catalyst design for highly active and selective multiphase catalysts.

Cr-MOF composited with facet-engineered bimetallic alloys for inducing photocatalytic conversion of CO2 to C2H4

The design of efficient photocatalysts is crucial for photocatalytic CO2 reduction. This study developed photocatalysts based on MIL-101(Cr) composited with a facet-engineered Pt/Pd nanoalloy (PPNA). Photocatalytic performance evaluations show that MIL-101(Cr) loaded with PPNA exposing {111} facets, namely M-A(111), exhibits a CO2 to C2H4 conversion rate of 9.5 μmol g-1 h-1 in addition to the CO and CH4, whereas M-A(100) with PPNA exposing {100} facets gives CO2 conversion rates of 33.2 for CO and 9.3 μmol g-1 h-1 for CH4 without C2H4. In situ FT-IR revealed that M-A(111) can readily form C2 intermediates during the reaction. This work offers a strategy for the design of photocatalysts for CO2 reduction to C2H4.

Dipole field as charge-transfer bridge between Cu atomic clusters/PtCu alloy nanocubes and nitrogen-rich C3N5 for superior photocatalytic hydrogen evolution

Utilizing spontaneous polarization field to harness charge transfer kinetics is a promising strategy to boost photocatalytic performance. Herein, a novel Cu atom clusters/PtCu alloy nanocubes coloaded on nitrogen-rich triazole-based C3N5 (PtCu-C3N5) with dipole field was constructed through facile photo-deposition and impregnation method. The dipole field-drive spontaneous polarization in C3N5 acts as a charge-transfer bridge to promote directional electron migration from C3N5 to Cu atom clusters/PtCu alloy. Through the synergistic effects between Cu atom clusters, PtCu alloy and dipole field in C3N5, the optimized Pt2Cu3-C3N5 achieved a record-high performance with H2 formation rate of 4090.4 μmol g-1 h-1 under visible light, about 154.4-fold increase compared with pristine C3N5 (26.5 μmol g-1 h-1). Moreover, the apparent quantum efficiency was up to 25.33 % at 320 nm, which is greatly superior than most previous related-works. The directional charge transfer mechanism was analyzed in detail through various characterizations and DFT calculations. This work offers a novel pathway to construct high-efficiency multi-metal photocatalysts for solar energy conversion.

Unraveling the C-C Coupling Mechanism on Dual-Atom Catalysts for CO2/CO Reduction Reaction: The Critical Role of CO Hydrogenation

The electrochemical reduction reaction (RR) of CO to high value multicarbon products is highly desirable for carbon utilization. Dual transition metal atoms dispersed by N-doped graphene are able to be highly efficient catalysts for this process due to the synergy of the bimetallic sites for C-C coupling. In this work, we screened homonuclear dual-atom catalysts dispersed by N-doped graphene to investigate the potential in CO reduction to C2+ products by employing density functional theory calculations. We have demonstrated that the two adsorbed CO species on bimetallic sites cannot directly couple unless one of the CO molecules is hydrogenated. All the dual metal atom catalysts prefer a similar coupling mechanism, i.e., the asymmetric coupling of *CO on the bridged site and *CHO on the top site, while the Ni2 and Cu2 catalysts exhibit much better performance with moderate adsorption energies and low energy barriers. The enhanced activities are attributed to the decrease of the energy levels of *CO 2p states that weakens the metal-C bonding and thus facilitates the feasible C-C coupling with both low reaction energies and low barriers. These insights have revealed the significant role of the hydrogenation of CO species prior to the coupling step and may provide a theoretical perspective to understand the generation of C2+ products in the CO2/CORR.

Photocatalytic asymmetric C-C coupling for CO2 reduction on dynamically reconstructed Ruδ+-O/Ru0-O sites

Solar-driven CO2 reduction to value-added C2 chemicals is thermodynamically challenging due to multiple complicated steps. The design of active sites and structures for photocatalysts is necessary to improve solar energy efficiency. In this work, atomically dispersed Ru-O sites in RuxIn2-xO3 are constructed by interior lattice anchoring of Ru. This results in the dynamic reconstruction of Ruδ+-O/Ru0-O sites upon photoexcitation, which facilitates the CO2 activation, *CO intermediates adsorption, and C-C coupling as demonstrated by varied in situ techniques. A SiO2 core in RuxIn2-xO3/SiO2 construction further enhances the solar energy utilization and individual RuxIn2-xO3 nanocrystals dispersion for photocatalytic CO2 reduction reaction. It results in the maximum ethanol production rate up to 31.6 μmol/g/h with over 90% selectivity. DFT simulation reveals that the C2 dimer formation primarily underwent an asymmetric *CO-*CHO coupling route via a low-energy precedence ladder of *CHO. This work provides an insightful understanding of active sites with dynamic reconstruction towards asymmetric C-C coupling for CO2RR at the atomic scale.

Understanding the Electrochemical Carbon Dioxide Reduction Reaction Mechanism of Lattice Tuning of Copper by Silver Single-Crystal Surface

Intermolecular interactions and adsorbate coverage on a metal electrode's surface/interface play an important role in CO2 reduction reaction (CO2RR). Herein, the activity and selectivity of CO2RR on bimetallic electrode, where a full monoatomic Cu layer covers on Ag surface (CuML/Ag) are investigated by using density functional theory calculations. The surface geometric and electronic structure results indicate that there is high electrocatalytic activity for CO2RR on the CuML/Ag electrode. Specifically, the CuML/Ag surface can accelerate the H2O and CO2 adsorption and hydrogenation while lowering the reaction energy of the rate-determining step. The structure parameters of chemisorbed CO2 with and without H2O demonstrate that activated H2O not only promotes the C-O dissociation but also provides the protons required for CO2RR on the CuML/Ag electrode surface. Furthermore, the various reaction mechanism diagrams indicate that the CuML/Ag electrode has high selectivity for CO2RR, and the efficiency of products can be regulated by modulating the reaction's electric potential.

Integrable utilization of intermittent sunlight and residual heat for on-demand CO2 conversion with water

Abundant residual heat from industrial emissions may provide energy resource for CO2 conversion, which relies on H2 gas and cannot be accomplished at low temperatures. Here, we report an approach to store electrons and hydrogen atoms in catalysts using sunlight and water, which can be released for CO2 reduction in dark at relatively low temperatures (150-300 °C), enabling on-demand CO2 conversion. As a proof of concept, a model catalyst is developed by loading single Cu sites on hexagonal tungsten trioxide (Cu/WO3). Under light illumination, hydrogen atoms are generated through photocatalytic water splitting and stored together with electrons in Cu/WO3, forming a metastable intermediate (Cu/HxWO3). Subsequent activation of Cu/HxWO3 through low-temperature heating releases the stored electrons and hydrogen atoms, reducing CO2 into valuable products. Furthermore, we demonstrate the practical feasibility of utilizing natural sunlight to drive the process, opening an avenue for harnessing intermittent solar energy for CO2 utilization.

Upconversion Phosphor-Driven Photodegradation of Plastics

Plastic waste poses a profound threat to ecosystems and human health, necessitating novel strategies for effective degradation in nature. Here, we present a novel approach utilizing upconversion phosphors as additives to significantly accelerate plastic photodegradation in nature via enhancing ultraviolet (UV) radiation. Pr-doped Li2CaGeO4 (LCGO:Pr) upconversion phosphors readily converting blue light into deep-UV radiation, dramatically improve photodegradation rates for polyethylene (PE) and polyethylene terephthalate (PET) microplastics. In situ spectroscopic studies show that upconversion fluorescence initiates the photophysical cleavage of C-C and C-O bonds in the backbones of PE and PET, resulting in plastic degradation. Moreover, incorporating LCGO:Pr into polypropylene (PP) sheets realizes markedly enhanced photodamage, with the cracking area increasing by nearly 38-fold under simulated sunlight for 10 days. This underscores the potential of employing this approach for the construction of light-driven destructible polymers. Further optimization and exploration of material compatibility hold promise for developing sustainable photodegradable plastics.

Triggering Asymmetric Layer Displacement Polarization and Redox Dual-Sites Activation by Inside-Out Anion Substitution for Efficient CO2 Photoreduction

Sluggish bulk charge transfer and barren catalytic sites severely hinder the CO2 photoreduction process. Seeking strategies for accelerating charge dynamics and activating reduction and oxidation sites synchronously presents a huge challenge. Herein, an inside-out chlorine (Cl) ions substitution strategy on the layered polar Bi4O5Br2 is proposed for achieving layer structure-dependent polarization effect and redox dual-sites activation. Cl ions in the bulk phase shrink the halogen layer interspace by 8‰, triggering asymmetric [Bi4O5]2+ layer displacement polarization, prolonging the average photocharge lifetime to 201.8 ps. Meanwhile, surface substituted Cl ions enhance the electron-donating capability of neighboring Bi atoms, activating the intrinsic Bi reduction sites, and increasing H2O molecule adsorption on nearby intrinsic O oxidation site (cal. by 0.105 eV), also self-donating as an alien oxidation site. Besides, Cl upshifts the p-band center closer to the Fermi level, facilitating the reactant adsorption. Therefore, the energy barrier for CO2 activation and rate-limiting *COOH intermediate formation steps are significantly decreased. Without cocatalysts and sacrificial reagents, inside-out Cl-substituted Bi4O5Br2 delivers a remarkable CO2-to-CO photoreduction rate of 50.18 µmol g-1 h-1, being one of the state-of-the-art catalysts. This finding offers insights into exploiting polarization at the molecular-level and enhances understanding of catalytic site activation.

Asymmetrically Coordinated Cu Dual-Atom-Sites Enables Selective CO2 Electroreduction to Ethanol

Electrochemical reduction of CO2 (CO2RR) to value-added liquid fuels is a highly attractive solution for carbon-neutral recycling, especially for C2+ products. However, the selectivity control to preferable products is a great challenge due to the complex multi-electron proton transfer process. In this work, a series of Cu atomic dispersed catalysts are synthesized by regulating the coordination structures to optimize the CO2RR selectivity. Cu2-SNC catalyst with a uniquely asymmetrical coordinated CuN2-CuNS site shows high ethanol selective with the FE of 62.6% at -0.8 V versus RHE and 60.2% at 0.9 V versus RHE in H-Cell and Flow-Cell test, respectively. Besides, the nest-like structure of Cu2-SNC is beneficial to the mass transfer process and the selection of catalytic products. In situ experiments and theory calculations reveal the reaction mechanisms of such high selectivity of ethanol. The S atoms weaken the bonding ability of the adjacent Cu to the carbon atom, which accelerates the selection from *CHCOH to generate *CHCHOH, resulting in the high selectivity of ethanol. This work indicates a promising strategy in the rational design of asymmetrically coordinated single, dual, or tri-atom catalysts and provides a candidate material for CO2RR to produce ethanol.

In Situ Generatable and Recyclable Oxygen Vacancy-Modified Fe2O3-Decorated WO3 Nanowires with Super Stability for ppb-Level H2S Sensing

Detecting hydrogen sulfide (H2S) odor gas in the environment at parts-per-billion-level concentrations is crucial. However, a significant challenge is the rapid deactivation caused by SO42- deposition. To address this issue, we developed a sensing material comprising Fe2O3-decorated WO3 nanowires (FWO) with strong interfacial interaction. During the H2S sensing process, important oxygen vacancies (OVs) are generated in situ and are recyclable on the surface of the Fe2O3 cluster. This sensor achieves a response of 140 (Ra/Rg) toward 50 ppm of H2S at 250 °C, with an experimentally measured detection limit of 1 ppb. It also exhibits remarkable stability, with no significant change observed over a long period of 150 days. Based on a combination of in situ DRIFT and DFT calculations, we have identified that the overactivation of O2 is the key step in the formation of SO42-. This overactivation can be partially modulated by the synergistic effect of Fe2O3 decoration and the in situ generated OVs, regulating the oxidation product to SO2 rather than the toxic SO42-. Furthermore, the continuous generation of OVs compensates for the loss of active sites pertaining to SO42- deposition, thereby contributing to the excellent stability of the sensor. This study underscores the beneficial impact of in situ OV generation in FWO for H2S sensing, offering a dynamic strategy to enhance sensor performance, particularly in terms of stability.

Unlocking Copper-Free Interfacial Asymmetric C-C Coupling for Ethylene Photosynthesis from CO2 and H2O

Solar-driven carbon dioxide (CO2) reduction into C2+ products such as ethylene represents an enticing route toward achieving carbon neutrality. However, due to sluggish electron transfer and intricate C-C coupling, it remains challenging to achieve highly efficient and selective ethylene production from CO2 and H2O beyond capitalizing on Cu-based catalysts. Herein, we report a judicious design to attain asymmetric C-C coupling through interfacial defect-rendered tandem catalytic centers within a sulfur-vacancy-rich MoSx/Fe2O3 photocatalyst sheet, enabling a robust CO2 photoreduction to ethylene without the need for copper, noble metals, and sacrificial agents. Specifically, interfacial S vacancies induce adjacent under-coordinated S atoms to form Fe-S bonds as a rapid electron-transfer pathway for yielding a Z-scheme band alignment. Moreover, these S vacancies further modulate the strong coupling interaction to generate a nitrogenase-analogous Mo-Fe heteronuclear unit and induce the upward shift of the d-band center. This bioinspired interface structure effectively suppresses electrostatic repulsion between neighboring *CO and *COH intermediates via d-p hybridization, ultimately facilitating an asymmetric C-C coupling to achieve a remarkable solar-to-chemical efficiency of 0.565% with a superior selectivity of 84.9% for ethylene production. Further strengthened by MoSx/WO3, our design unveils a promising platform for optimizing interfacial electron transfer and offers a new option for C2+ synthesis from CO2 and H2O using copper-free and noble metal-free catalysts.

Synergism between copper and silver nanoclusters induces fascinating structural modifications, properties, and applications

Among the group 11 transition metal elements, Cu and Ag are widely studied due to their cost effectiveness and easy availability. However, the synergism between copper and silver is also very promising, exhibiting intriguing structures, properties, and applications. Nanoclusters, which are missing links between atoms and nanoparticles, are highly fluorescent due to their discrete energy levels. Their fluorescence can be efficiently tuned because of the synergistic behaviour of copper and silver. Furthermore, their fluorescence can be selectively altered in the presence of various analytes and sensing platforms, as reported by various groups. Moreover, copper clusters can be utilized for sensing silver while silver nanoclusters can be utilized for sensing ionic copper due to the strong interaction between copper and silver. Furthermore, DFT studies have been performed to understand the structural modification due to CuAg synergism. A concise summary of the synergism between copper and silver can open a new window of research for young scientists venturing into the field of environmental nanoscience.

Au Cluster-Nanoparticle Dual Coupling for Photocatalytic CO2 Conversion

CO2-selective photoreduction to value-added products is ideal, but its practical application suffers from weak photogenerated carrier separation and insufficient multielectron transport. Herein, we constructed the tricomponent AuNPs@SnO2-AuNCs hybrid by decorating Au nanoclusters (AuNCs) on the Au nanoparticle (AuNPs)@SnO2 core-shell structure. AuNC-NP dual coupling endowed AuNPs@SnO2-AuNCs with an excellent CO yield of 64.8 μmol g-1 h-1 during CO2 photoreduction, which was higher than the role of separate application of AuNCs (25.3 μmol g-1 h-1) and AuNPs (16.0 μmol g-1 h-1). It was mainly attributed that the coaction of AuNPs and AuNCs not only enhanced the visible light absorption capacity but also improved the photogenerated carrier separation/migration. As a result, the electron-rich AuNCs induced from plasmonic AuNPs and photoexcited SnO2 promoted the photocatalytic CO2-to-CO performance. This work provides a new perspective to design multicomponent photocatalysts for highly efficient CO2 conversion.

Plasmon-Driven Highly Selective CO2 Photoreduction to C2H4 on Ionic Liquid-Mediated Copper Nanowires

Selective CO2 photoreduction to value-added multi-carbon (C2+) feedstocks, such as C2H4, holds great promise in direct solar-to-chemical conversion for a carbon-neutral future. Nevertheless, the performance is largely inhibited by the high energy barrier of C-C coupling process, thereby leading to C2+ products with low selectivity. Here we report that through facile surface immobilization of a 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM-BF4) ionic liquid, plasmonic Cu nanowires could enable highly selective CO2 photoreduction to C2H4 product. At an optimal condition, the resultant plasmonic photocatalyst exhibits C2H4 production with selectivity up to 96.7 % under 450 nm monochromatic light irradiation, greatly surpassing its pristine Cu counterpart. Combined in situ spectroscopies and computational calculations unravel that the addition of EMIM-BF4 ionic liquid modulates the local electronic structure of Cu, resulting in its enhanced adsorption strength of *CO intermediate and significantly reduced energy barrier of C-C coupling process. This work paves new path for Cu surface plasmons in selective artificial photosynthesis to targeted products.

Strong Dipole Moments from Ferrocene Methanol Clusters Boost Exciton Dissociation in Quantum-Confined Perovskite for CO2 Photoreduction

Perovskite nanocrystals (PCNs) exhibit a significant quantum confinement effect that enhances multiexciton generation, making them promising for photocatalytic CO2 reduction. However, their conversion efficiency is hindered by poor exciton dissociation. To address this, we synthesized ferrocene-methanol-functionalized CsPbBr3 (CPB/FcMeOH) using a ligand engineering approach. By manipulating the electronic coupling between ligands and the PCN surface, facilitated by the increased dipole moment from hydrogen bonding in FcMeOH molecules, we effectively controlled exciton dissociation and interfacial charge transfer. Under 5 h of irradiation, the CO yield of CPB/FcMeOH reached 772.79 μmol g-1, 4.95 times higher than pristine CPB. This high activity is due to the formation of hydrogen-bonded FcMeOH clusters on the CPB surface. The nonpolar disruption and strong dipole moment of FcMeOH molecules enhance electronic coupling between the FcMeOH ligands and the CPB surface, reducing the surface barrier energy. Consequently, exciton dissociation and interfacial charge transfer are promoted, efficiently utilizing multiple excitons in quantum-confined domains. Transient absorption spectroscopy confirms that CPB/FcMeOH exhibits optimized exciton behavior with fast internal relaxation, trapping, and a short recombination time, allowing photogenerated charges to more rapidly participate in CO2 reduction.

Predicting and understanding photocatalytic CO2 reduction reaction with IR spectroscopy-based interpretable machine learning framework

The highly selective conversion of carbon dioxide into value-added products is extremely valuable. However, even with the aid of in situ characterization techniques, it remains challenging to directly correlate extensive spectral data carrying microscopic information with macroscopic performance. Herein, we adopted advanced machine learning (ML) approaches to establish an accurate and interpretable relationship between vibrational spectral signals and catalytic performances to uncover hidden physical insights. Focusing on photocatalytic CO2 reduction, our model is shown to effectively and accurately predict the CO production activity and selectivity based solely on the infrared (IR) spectral signals, the generalizability of which is additionally demonstrated with a new Bi5O7I photocatalytic system. More importantly, further model analysis has revealed a novel strategy to steer CO selectivity, the physical sanity of which is verified by a detailed reaction mechanism analysis. This work demonstrates the tremendous potential of machine-learned spectroscopy to efficiently identify reaction control factors, which can further lay the foundation for targeted optimization and reverse design.

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.

Recent advances of metal active sites in photocatalytic CO2 reduction

Photocatalytic CO2 reduction captures solar energy to convert CO2 into hydrocarbon fuels, thus shifting the dependence on rapidly depleting fossil fuels. Among the various proposed photocatalysts, systems containing metal active sites (MASs) possess obvious advantages, such as effective photogenerated carrier separation, suitable adsorption and activation of intermediates, and achievable C-C coupling to generate multi-carbon (C2+) products. The present review aims to summarize the typical photocatalytic materials with MAS, highlighting the critical role of different formulations of MAS in CO2 photoreduction, especially for C2+ product generation. State-of-the-art progress in the characterization and theoretical calculations for MAS-containing photocatalysts is also emphasized. Finally, the challenges and prospects of catalytic systems involving MAS for solar-driven CO2 conversion are outlined, providing inspiration for the future design of materials for efficient photocatalytic energy conversion.

Cascaded *CO-*COH Intermediates on a Nonmetallic Plasmonic Photocatalyst for CO2-to-C2H6 with 90.6 % Selectivity

Oxygen vacancies (OV) in nonmetallic plasmonic photocatalysts can decrease the energy barrier for CO2 reduction, boosting C1 intermediate production for potential C2 formation. However, their susceptibility to oxidation weakens C1 intermediate adsorption. Herein we proposed a "photoelectron injection" strategy to safeguard OV in W18O49 by creating a W18O49/ZIS (W/Z) plasmonic photocatalyst. Moreover, photoelectrons contribute to the local multi-electron environment of W18O49, enhancing the intrinsic excitation of its hot electrons with extended lifetimes, as confirmed by in situ XPS and femtosecond transient absorption analysis. Density functional theory calculations revealed that W/Z with OV enhances CO2 adsorption, activating *CO production, while reducing the energy barrier for *COH production (0.054 eV) and subsequent *CO-*COH coupling (0.574 eV). Successive hydrogenation revealed that the free energy for *CH2CH2 hydrogenation (0.108 eV) was lower than that for *CH2CH2 desorption for C2H4 production (0.277 eV), favouring C2H6 production. Consequently, W/Z achieves an efficient C2H6 activity of 653.6 μmol g-1 h-1 under visible light, with an exceptionally high selectivity of 90.6 %. This work offers a new strategy for the rational design of plasmonic photocatalysts with high selectivity for C2+ products.

Overcoming Electrostatic Interaction via Pulsed Electroreduction for Boosting the Electrocatalytic Urea Synthesis

Electrocatalytic urea synthesis under ambient conditions offers a promising alternative strategy to the traditional energy-intensive urea industry protocol. Limited by the electrostatic interaction, the reduction reaction of anions at the cathode in the electrocatalytic system is not easily achievable. Here, we propose a novel strategy to overcome electrostatic interaction via pulsed electroreduction. We found that the reconstruction-resistant CuSiOx nanotube, with abundant atomic Cu-O-Si interfacial sites, exhibits ultrastability in the electrosynthesis of urea from nitrate and CO2. Under a pulsed potential approach with optimal operating conditions, the Cu-O-Si interfaces achieve a superior urea production rate (1606.1 μg h-1 mgcat. -1) with high selectivity (79.01 %) and stability (the Faradaic efficiency is retained at 80 % even after 80 h of testing), outperforming most reported electrocatalytic synthesis urea catalysts. We believe our strategy will incite further investigation into pulsed electroreduction increasing substrate transport, which may guide the design of ambient urea electrosynthesis and other energy conversion systems.

High-Rate and Selective C2H6-to-C2H4 Photodehydrogenation Enabled by Partially Oxidized Pdδ+ Species Anchored on ZnO Nanosheets under Mild Conditions

Photocatalytic C2H6-to-C2H4 conversion is very promising, yet it remains a long-lasting challenge due to the high C-H bond dissociation energy of 420 kJ mol-1. Herein, partially oxidized Pdδ+ species anchored on ZnO nanosheets are designed to weaken the C-H bond by the electron interaction between Pdδ+ species and H atoms, with efforts to achieve high-rate and selective C2H6-to-C2H4 conversion. X-ray photoelectron spectra, Bader charge calculations, and electronic localization function demonstrate the presence of partially oxidized Pdδ+ sites, while quasi-in situ X-ray photoelectron spectra disclose the Pdδ+ sites initially adopt and then donate the photoexcited electrons for C2H6 dehydrogenation. In situ electron paramagnetic resonance spectra, in situ Fourier transform infrared spectra, and trapping agent experiments verify C2H6 initially converts to CH3CH2OH via ·OH radicals, then dehydroxylates to CH3CH2· and finally to C2H4, accompanied by H2 production. Density-functional theory calculations elucidate that loading Pd site can lengthen the C-H bond of C2H6 from 1.10 to 1.12 Å, which favors the C-H bond breakage, affirmed by a lowered energy barrier of 0.04 eV. As a result, the optimized 5.87% Pd-ZnO nanosheets achieve a high C2H4 yield of 16.32 mmol g-1 with a 94.83% selectivity as well as a H2 yield of 14.49 mmol g-1 from C2H6 dehydrogenation in 4 h, outperforming all the previously reported photocatalysts under similar conditions.

Ice-Templated Synthesis of Atomic Cluster Cocatalyst with Regulable Coordination Number for Enhanced Photocatalytic Hydrogen Evolution

Supported metal catalysts have been exploited in various applications. Among them, cocatalyst supported on photocatalyst is essential for activation of photocatalysis. However, cocatalyst decoration in a controllable fashion to promote intrinsic activity remains challenging. Herein, a versatile method is developed for cocatalyst synthesis using an ice-templating (ICT) strategy, resulting in size control from single-atom (SA), and atomic clusters (AC) to nanoparticles (NP). Importantly, the coordination numbers (CN) of decorated AC cocatalysts are highly controllable, and this ICT method applies to various metals and photocatalytic substrates. Taking narrow-band gap Ga-doped La5Ti2Cu0.9Ag0.1O7S5 (LTCA) photocatalyst as an example, supported Ru AC/LTCA catalysts with regulable Ru CNs have been prepared, delivering significantly enhanced activities compared to Ru SA and Ru NPs supported on LTCA. Specifically, Ru(CN = 3.4) AC/LTCA with an average CN of Ru─Ru bond measured to be ≈3.4 exhibits excellent photocatalytic H2 evolution rate (578 µmol h-1) under visible light irradiation. Density functional theory calculation reveals that the modeled Ru(CN = 3) atomic cluster cocatalyst possesses favorable electronic properties and available active sites for the H2 evolution reaction.

Bimetallic Cu@Ru Core-Shell Structures with Ligand Effects for Endo-Exogenous Stimulation-Mediated Dynamic Oncotherapy

Dynamic therapies, which induce reactive oxygen species (ROS) production in situ through endogenous and exogenous stimulation, are emerging as attractive options for tumor treatment. However, the complexity of the tumor substantially limits the efficacy of individual stimulus-triggered dynamic therapy. Herein, bimetallic copper and ruthenium (Cu@Ru) core-shell nanoparticles are applied for endo-exogenous stimulation-triggered dynamic therapy. The electronic structure of Cu@Ru is regulated through the ligand effects to improve the adsorption level for small molecules, such as water and oxygen. The core-shell heterojunction interface can rapidly separate electron-hole pairs generated by ultrasound and light stimulation, which initiate reactions with adsorbed small molecules, thus enhancing ROS generation. This synergistically complements tumor treatment together with ROS from endogenous stimulation. In vitro and in vivo experiments demonstrate that Cu@Ru nanoparticles can induce tumor cell apoptosis and ferroptosis through generated ROS. This study provides a new paradigm for endo-exogenous stimulation-based synergistic tumor treatment.

Ruthenium-Cobalt Solid-Solution Alloy Nanoparticles for Enhanced Photopromoted Thermocatalytic CO2 Hydrogenation to Methane

Bimetallic alloy nanoparticles have garnered substantial attention for diverse catalytic applications owing to their abundant active sites and tunable electronic structures, whereas the synthesis of ultrafine alloy nanoparticles with atomic-level homogeneity for bulk-state immiscible couples remains a formidable challenge. Herein, we present the synthesis of RuxCo1-x solid-solution alloy nanoparticles (ca. 2 nm) across the entire composition range, for highly efficient, durable, and selective CO2 hydrogenation to CH4 under mild conditions. Notably, Ru0.88Co0.12/TiO2 and Ru0.74Co0.26/TiO2 catalysts, with 12 and 26 atom % of Ru being substituted by Co, exhibit enhanced catalytic activity compared with the monometallic Ru/TiO2 counterparts both in dark and under light irradiation. The comprehensive experimental investigations and density functional theory calculations unveil that the electronic state of Ru is subtly modulated owing to the intimate interaction between Ru and Co in the alloy nanoparticles, and this effect results in the decline in the CO2 conversion energy barrier, thus ultimately culminating in an elevated catalytic performance relative to monometallic Ru and Co catalysts. In the photopromoted thermocatalytic process, the photoinduced charge carriers and localized photothermal effect play a pivotal role in facilitating the chemical reaction process, which accounts for the further boosted CO2 methanation performance.

Improved Charge Separation and CO2 Affinity of In2O3 by K Doping with Accompanying Oxygen Vacancies for Boosted CO2 Photoreduction

The CO2 photocatalytic conversion efficiency of the semiconductor photocatalyst is always inhibited by the sluggish charge transfer and undesirable CO2 affinity. In this work, we prepare a series of K-doped In2O3 catalysts with concomitant oxygen vacancies (OV) via a hydrothermal method, followed by a low-temperature sintering treatment. Owing to the synergistic effect of K doping and OV, the charge separation and CO2 affinity of In2O3 are synchronously promoted. Particularly, when P/P0 = 0.010, at room temperature, the CO2 adsorption capacity of the optimal K-doped In2O3 (KIO-3) is 2336 cm3·g-1, reaching about 6000 times higher than that of In2O3 (0.39 cm3·g-1). As a result, in the absence of a cocatalyst or sacrificial agent, KIO-3 exhibits a CO evolution rate of 3.97 μmol·g-1·h-1 in a gas-solid reaction system, which is 7.6 times that of pristine In2O3 (0.52 μmol·g-1·h-1). This study provides a novel approach to the design and development of efficient photocatalysts for CO2 conversion by element doping.

Dynamically Cyclic Fe2+/Fe3+ Active Sites as Electron and Proton-Feeding Centers Boosting CO2 Photoreduction Powered by Benzyl Alcohol Oxidation

Solar-driven CO2 photoreduction holds promise for sustainable fuel and chemical productions, but the complex proton-coupled multi-electron transfer processes and sluggish oxidation half-reaction kinetics substantially hinder its efficiency. Here, we devised a rational catalyst design to address these challenges by fabricating ferrocene carboxylic acid-functionalized Cs3Sb2Br9 nanocrystals (CSB-Fc NCs), which facilitate simultaneous benzyl alcohol oxidation and CO2 reduction reactions under visible-light irradiation. The synchronized proton-coupled electron transfer processes between the reduction and oxidation half-reactions on CSB-Fc NCs resulted in a 5-fold increase in the CO2 reduction rate (45.56 μmol g-1 h-1, 97.9% CO selectivity) and a 5.8-fold enhancement in benzyl alcohol conversion (97.7% selectivity for benzaldehyde) compared to the CSB. In situ Raman and ultraviolet-visible diffuse reflectance spectra revealed that the dynamic Fe2+/Fe3+ redox loop within the Fc unit serves as the actual active site, facilitating the activation of substrate molecules. More importantly, in situ attenuated total reflection Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry spectroscopy, with isotope labeling of Deuteron-benzyl alcohol and 13CO2, confirmed that proton transfer from the hydroxyl group generates reactive protons at the Fe2+/Fe3+ site, enabling efficient CO2 photoreduction through subsequent protonation steps. This work offers a cost-effective and efficient approach for synergetic CO2 photoreduction driven by organic synthesis, advancing solar energy utilization.