Investigating the Hybrid-Structure-Effect of CeO2 -Encapsulated Au Nanostructures on the Transfer Coupling of Nitrobenzene

Electrochemical hydrogenative coupling of nitrobenzene into azobenzene over a mesoporous palladium-sulfur cathode

Azobenzene (AZO) and its derivatives are of great importance in the dyestuff and pharmaceutical industries; however, their sustainable synthesis is much slower than expected due to the lack of high-performance catalysts. In this work, we report a robust yet highly efficient catalyst of PdS mesoporous nanospheres (MNSs) with confined mesostructures and binary elemental composition that achieved sustainable electrosynthesis of value-added AZO by selective hydrogenative coupling of nitrobenzene (NB) feedstocks in H2O under ambient conditions. Using a renewable electricity source and H2O, binary PdS MNSs exhibited a remarkable NB conversion of 95.4%, impressive AZO selectivity of 93.4%, and good cycling stability in selective NB hydrogenation reaction (NBHR) electrocatalysis. Detailed mechanism studies revealed that the confined mesoporous microenvironment of PdS MNSs facilitated the hydrogenative coupling of key intermediates (nitrosobenzene and phenylhydroxylamine) into AZO and/or azoxybenzene (AOB), while their electron-deficient S sites stabilized the Pd-spillovered active H* and inhibited the over-hydrogenation of AZO/AOB into AN. By coupling with the anodic methanol oxidation reaction (MOR), the (-)NBHR‖MOR(+) two-electrode system exhibits much better NB-to-AZO performance in a sustainable and energy-efficient manner. This work thus paves the way for designing functional mesoporous metal alloy electrocatalysts applied in the sustainable electrosynthesis of industrial value-added chemicals.

Precision therapeutics for inflammatory bowel disease: advancing ROS-responsive nanoparticles for targeted and multifunctional drug delivery

Inflammatory bowel disease (IBD) is a severe chronic intestinal disorder with a rising global incidence. Current therapies, including the delivery of anti-inflammatory drugs and probiotics, face significant challenges in terms of safety, stability, and efficacy. In IBD patients, the activity of antioxidant enzymes (e.g., superoxide dismutase, glutathione peroxidase, and glutathione reductase) is reduced at the site of intestinal inflammation, leading to the accumulation of reactive oxygen species (ROS). This accumulation damages the intestinal mucosa, disrupts tight junctions between cells, and compromises the integrity of the intestinal barrier, exacerbating IBD symptoms. Therefore, nanoparticles responsive to ROS and capable of mimicking antioxidant enzyme activity, such as boronates, polydopamine, sulfides, and metal nanozymes, have emerged as promising tools. These nanoparticles can respond to elevated ROS levels in inflamed intestinal regions and release drugs to effectively neutralize ROS, making them ideal candidates for IBD treatment. This review discusses the application of various ROS-responsive nanomaterial delivery systems in IBD therapy, highlights current challenges, and outlines future research directions. Furthermore, we explore the "layered programmable delivery" strategy, which combines ROS-responsive nanoparticles with pH-responsive and cell membrane-targeted nanoparticles. This strategy has the potential to overcome the limitations of single-mechanism targeted drug delivery, enabling multi-range and multi-functional treatment approaches that significantly enhance delivery efficiency, providing new insights for the future of localized IBD treatment.

Visible-light-induced synthesis of bibenzofuranones via a cerium-mediated energy transfer process

Benzofuran-3(2H)-one compounds are important bioactive molecules. Synthesis of bibenzofuranones from benzils via a radical cyclization-dimerization tandem process, efficiently constructing the C-O/C-C bonds and contiguous quaternary carbon centers in a single step was reported. This reaction exhibits high regioselectivity, affording bibenzofuranones in moderate to excellent yields under mild conditions. Mechanistic studies suggest that cerium sulfate serves as both an energy transfer reagent and an oxidant in this process.

Theoretical study on nitrobenzene hydrogenation to aniline catalyzed by M1/CeO2-x(111) single-atom catalysts

The hydrogenation of nitrobenzene to aniline is a critical process in the production of numerous chemical intermediates and pharmaceuticals. Developing efficient catalysts for this reaction is essential to improve reaction rates and selectivity. A density functional theory (DFT) study was performed to investigate the catalytic activity of twelve late transition metal-doped ceria (M1/CeO2-x(111)) single-atom catalysts for the hydrogenation of nitrobenzene to aniline. Firstly, the stabilities and oxidation states of doped metal atoms on M1/CeO2-x(111) surfaces were studied. Subsequently, the reactivity of two possible rate-determining steps on M1/CeO2-x(111) surfaces, H2 dissociation and the fourth hydrogen transfer step in the direct route of nitrobenzene hydrogenation (PhNHO* + H* → PhNHOH*), was further investigated. The Brønsted-Evans-Polanyi (BEP) relationship between reaction energies (ΔE) and activation energies (Ea) and the volcano plot between the energies of PhNHOH* (EPhNHOH*) and the activation energies (Ea) of the fourth hydrogen transfer step were identified. The calculated results indicate that the fourth hydrogen transfer step is the rate-determining step in the overall reaction, and that the Ru1/CeO2-x(111) single-atom catalyst could be one of the most promising catalysts with good catalytic activity for the nitrobenzene hydrogenation.

Moderate Active Hydrogen Generation over a Ni2P/CoP Heterostructure for One-Step Electrosynthesizing of Azobenzene with High Selectivity

Through hydrogenation and N-N coupling, azobenzene can be produced via highly selective electrocatalytic nitrobenzene reduction, offering a mild, cost-effective, and sustainable industrial route. Inspired by the density functional theory calculations, the introduction of H* active Ni2P into CoP, which reduces the water dissociation energy barrier, optimizes H* adsorption, and moderates key intermediates' adsorption, is expected to assist its hydrogenation ability for one-step electrosynthesizing azobenzene. A self-supported NiCo@Ni2P/CoP nanorod array electrode was synthesized, featuring NiCo alloy nanoparticles within a Ni2P/CoP shell. By virtue of the thermodynamically optimal Ni2P/CoP heterostructure, along with overall fast electron transport in a core-shell integrated electrode, NiCo@Ni2P/CoP with abundant interfacial structure attains a great nitrobenzene conversion of 94.3%, especially prominent azobenzene selectivity of 97.2%, and Faradaic efficiency of 94.1% at -0.9 V (vs Hg/HgO). High-purity azobenzene crystals can also self-separate under refrigeration postelectrolysis. This work provides an energy-efficient and scalable pathway for the economical preparation of azobenzene in the electrocatalytic nitrobenzene hydrogenation.

Effect of the ZrO2 Crystal Phase on Performance over a CuCeZrO Catalyst for Dehydrogenative Condensation of Ethanol to Ethyl Acetate

Ethyl acetate is an important chemical, and ethanol dehydrogenative condensation with 95.6% atomic economy is a promising synthetic route. CuZrO-based catalysts are widely applied in this reaction; however, the effect of the ZrO2 crystal phase in the CuCeZrO catalyst upon reaction deserves to be explored further. Herein, the ZrO2 crystal phase in the CuCeZrO catalyst was regulated by controlling the calcination temperature, and a high temperature (≥600 °C) is conducive to the transformation of the tetragonal phase to the monoclinic phase. Additionally, monoclinic ZrO2 (m-ZrO2) with limited density of the strong base is found to be more beneficial to the selective production of ethyl acetate from ethanol, while tetragonal ZrO2 (t-ZrO2) with abundant strongly basic sites is more inclined to the formation of butanol and its downstream esters. This work not only improves our understanding of the crystal phase effect in a CuCeZrO catalytic system but also paves the way for the development of more efficient catalysts for ethyl acetate production.

Universal, Time-Cost-Effective, and Inside-Out Strategy for Synthesis of Plant-Based Flow Catalysis Microreactors

The utilization of plant-based flow catalytic microreactors has been increasingly gaining traction in the fields of water treatment, energy generation, and biotechnological science due to their inherent channel structures, renewable properties, and environmentally friendly nature. The conventional outside-in strategy for synthesizing plant-based monolithic microreactors typically entails prolonged hydrothermal modification, extensive chemical usage, or energy-intensive equipment. The present study presents a universal inside-out strategy for the rapid synthesis of monolithic catalytic microreactors derived from plant materials. This approach enables the direct formation of catalytic metal nanoparticles within specific plant microchannels through regioselective deposition, resulting in reduced chemical usage and an accelerated process. Moreover, this method effectively minimizes the required catalyst dosage. In this process, the plant monolith's aligned, narrow, and accessible channels provided a higher contact area, shorter diffusion path, and abundant oxygen-containing functional groups for rapid transformation of metal salt precursors into catalytic metal nanoparticles with excellent dispersion. The inside-out strategy can be extended to various plant-based monoliths and diverse metal/metal oxide/MOF materials within the plant monolith, thereby offering a facile, time- and cost-effective universal approach for skillfully designing plant-based flow microreactors for a wide range of applications.

Au-modified ceria nanozyme prevents and treats hypoxia-induced pulmonary hypertension with greatly improved enzymatic activity and safety

BACKGROUND

Despite recent advances the prognosis of pulmonary hypertension remains poor and warrants novel therapeutic options. Extensive studies, including ours, have revealed that hypoxia-induced pulmonary hypertension is associated with high oxidative stress. Cerium oxide nanozyme or nanoparticles (CeNPs) have displayed catalytic activity mimicking both catalase and superoxide dismutase functions and have been widely used as an anti-oxidative stress approach. However, whether CeNPs can attenuate hypoxia-induced pulmonary vascular oxidative stress and pulmonary hypertension is unknown.

RESULTS

In this study, we designed a new ceria nanozyme or nanoparticle (AuCeNPs) exhibiting enhanced enzyme activity. The AuCeNPs significantly blunted the increase of reactive oxygen species and intracellular calcium concentration while limiting proliferation of pulmonary artery smooth muscle cells and pulmonary vasoconstriction in a model of hypoxia-induced pulmonary hypertension. In addition, the inhalation of nebulized AuCeNPs, but not CeNPs, not only prevented but also blunted hypoxia-induced pulmonary hypertension in rats. The benefits of AuCeNPs were associated with limited increase of intracellular calcium concentration as well as enhancement of extracellular calcium-sensing receptor (CaSR) activity and expression in rat pulmonary artery smooth muscle cells. Nebulised AuCeNPs showed a favorable safety profile, systemic arterial pressure, liver and kidney function, plasma Ca2+ level, and blood biochemical parameters were not affected.

CONCLUSION

We conclude that AuCeNPs is an improved reactive oxygen species scavenger that effectively prevents and treats hypoxia-induced pulmonary hypertension.

Scalable synthesis of Au@CeO2 nanozyme for development of colorimetric lateral flow immunochromatographic assay to sensitively detect heart-type fatty acid binding protein

Nanozymes with core@shell nanostructure are considered promising biolabeling materials for their multifunctional properties. In this work, a simple one-pot strategy has been proposed for scalable synthesis of gold@cerium dioxide core@shell nanoparticles (Au@CeO2 NPs) with strong localized surface plasmon resonance (LSPR) absorption and high peroxidase-like catalytic activity by redox reactions of Ce3+ ions and AuCl4- ions in diluted ammonia solution under room temperature. A colorimetric lateral flow immunochromatographic assay (LFIA) has been successfully fabricated for sensitive detection of heart-type fatty acid binding protein (H-FABP, an early cardiac biomarker) by using the Au@CeO2 NPs as reporters. The as-developed LFIA with Au@CeO2 NP reporter (termed as Au@CeO2-LFIA) exhibits a dynamic range of nearly two orders of magnitude, and a limit of detection (LOD) as low as 0.35 ng mL-1 H-FABP with nanozyme-triggered 3,3',5,5'-tetramethylbenzidine (TMB) colorimetric amplification. Furthermore, the practicality of Au@CeO2-LFIA has been demonstrated by profiling the concentrations of H-FABP in 156 blood samples of acute myocardial infarction (AMI) patients, and satisfactory results are obtained.

Synergy of Oxygen Vacancies and Base Sites for Transfer Hydrogenation of Nitroarenes on Ceria Nanorods

CeO2 nanorod based catalysts for the base-free synthesis of azoxy-aromatics via transfer hydrogenation of nitroarenes with ethanol as hydrogen donor have been synthesized and investigated. The oxygen vacancies (Ov ) and base sites are critical for their excellent catalytic properties. The Ov , i.e., undercoordinated Ce cations, serve as the sites to activate ethanol and nitroarenes by lowering the energy barrier to transfer hydrogen from α-Csp3 -H in ethanol to the nitro group coupling it to the redox reactions between Ce3+ and Ce4+ . At the same time, the base sites catalyze the condensation step to selectively produce azoxy-aromatics. The catalytic route opens a much improved way to use non-noble metal oxides without additives for the selective functional group reduction and coupling reactions.

One-pot synthesis of AuPt@FexOy nanoparticles with excellent peroxidase-like activity for development of ultrasensitive colorimetric lateral flow immunoassay of cardiac troponin I

Detection of cardiac troponin I (cTnI) plays a critical role in diagnosing acute myocardial infarction (AMI). In this report, a new kind of spherical AuPt@FexOy core@shell nanoparticles (termed as AuPt@FexOy NPs) were one-pot synthesized by a redox interaction-engaged strategy (RIES) without the addition of any surfactants or reducing agents. The as-synthesized AuPt@FexOy NPs not only retain the plasmonic activity of gold nanoparticles (AuNPs), but also possess excellent catalytic activities of platinum nanoparticles (PtNPs) and FexOy nanoclusters. The features of AuPt@FexOy NPs enable greatly enhance the colorimetric detection sensitivity of lateral flow immunoassay (LFIA) through integrating AuPt@FexOy NPs labeling procedure and catalyzing oxidation of chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) signal amplification strategy. The as-developed colorimetric LFIA (termed as AuPt@FexOy-LFIA) exhibits the limit of detection (LOD) as 26.0 pg mL-1 cTnI under the TMB signal amplification mode. In particular, the detection results of cTnI in 40 clinical seral samples by AuPt@FexOy-LFIA are correlated well with those of cTnI in the same samples by commercial enzyme-linked immunosorbent assay (ELISA) detection kit (R2 = 0.97, slope = 1), demonstrating the highly reliable analytical performance and good application prospect of AuPt@FexOy-LFIA.

Structure engineering of CeO2 for boosting the Au/CeO2 nanocatalyst in the green and selective hydrogenation of nitrobenzene

Exploring eco-friendly and cost-effective strategies for structure engineering at the nanoscale is important for boosting heterogeneous catalysis but still under a long-standing challenge. Herein, multifunctional polyphenol tannic acid, a low-cost natural biomass containing catechol and galloyl species, was employed as a green reducing agent, chelating agent, and stabilizer to prepare Au nanoparticles, which were dispersed on different-shaped CeO₂ supports (e.g., rod, flower, cube, and octahedral). Systematic characterizations revealed that Au/CeO₂-rod had the highest oxygen vacancy density and Ce(III) proportion, favoring the dispersion and stabilization of the metal active sites. Using isopropanol as a hydrogen-transfer reagent, deep insights into the structure-activity relationship of the Au/CeO₂ catalysts with various morphologies of CeO₂ in the catalytic nitrobenzene transfer hydrogenation reaction were gained. Notably, the catalytic performance followed the order: Au/CeO₂-rod (110), (100), (111) > Au/CeO₂-flower (100), (111) > Au/CeO₂-cube (100) > Au/CeO₂-octa (111). Au/CeO₂-rod displayed the highest conversion of 100% nitrobenzene and excellent stability under optimal conditions. Moreover, DFT calculations indicated that nitrobenzene molecules had a suitable adsorption energy and better isopropanol dehydrogenation capacity on the Au/CeO₂ (110) surface. A reaction pathway and the synergistic catalytic mechanism for catalytic nitrobenzene transfer hydrogenation are proposed based on the results. This work demonstrates that CeO₂ structure engineering is an efficient strategy for fabricating advanced and environmentally benign materials for nitrobenzene hydrogenation.

Dynamic Reconstitution Between Copper Single Atoms and Clusters for Electrocatalytic Urea Synthesis

Electrocatalytic CN coupling between carbon dioxide and nitrate has emerged to meet the comprehensive demands of carbon footprint closing, valorization of waste, and sustainable manufacture of urea. However, the identification of catalytic active sites and the design of efficient electrocatalysts remain a challenge. Herein, the synthesis of urea catalyzed by copper single atoms decorated on a CeO₂ support (denoted as Cu₁ -CeO₂ ) is reported. The catalyst exhibits an average urea yield rate of 52.84 mmol h^-1 g_cat. ^-1 at -1.6 V versus reversible hydrogen electrode. Operando X-ray absorption spectra demonstrate the reconstitution of copper single atoms (Cu₁ ) to clusters (Cu₄ ) during electrolysis. These electrochemically reconstituted Cu₄ clusters are real active sites for electrocatalytic urea synthesis. Favorable CN coupling reactions and urea formation on Cu₄ are validated using operando synchrotron-radiation Fourier transform infrared spectroscopy and theoretical calculations. Dynamic and reversible transformations of clusters to single-atom configurations occur when the applied potential is switched to an open-circuit potential, endowing the catalyst with superior structural and electrochemical stabilities.

Gold nanoparticles-embedded ceria with enhanced antioxidant activities for treating inflammatory bowel disease

The excessive reactive oxygen species (ROS) is a hallmark associated with the initiation and progression of inflammatory bowel disease (IBD), which execrably form a vicious cycle of ROS and inflammation to continually promote disease progression. Here, the gold nanoparticles-embedded ceria nanoparticles (Au/CeO₂) with enhanced antioxidant activities are designed to block this cycle reaction for treating IBD by scavenging overproduced ROS. The Au/CeO₂ with core-shell and porous structure exhibits significantly higher enzymatic catalytic activities compared with commercial ceria nanoparticles, likely due to the effective exposure of catalytic sites, higher content of Ce (III) and oxygen vacancy, and accelerated reduction from Ce (IV) to Ce (III). Being coated with negatively-charged hyaluronic acid, the Au/CeO₂@HA facilitates accumulation in inflamed colon tissues via oral administration, reduces pro-inflammatory cytokines, and effectively alleviates colon injury in colitis mice. Overall, the Au/CeO₂@HA with good biocompatibility is a promising nano-therapeutic for treating IBD.

Understanding the electrocatalytic mechanism of self-template formation of hierarchical Co9S8/Ni3S2 heterojunctions for highly selective electroreduction of nitrobenzene

Aqueous electrochemical nitroarene reduction reaction using H₂O as the sustainable hydrogen source is an emerging technology to produce functionalized anilines. However, the development of low-cost electrocatalysts and the fundamental mechanistic understanding of the selective NO-RR still remain challenging. Herein, self-supporting hierarchical nanosheets consisting of high-density Co₉S₈/Ni₃S₂ heterojunctions on Ni foam (Co₉S₈/Ni₃S₂-NF) are constructed via an in situ self-template strategy. With combined advantages of high-loading, high surface exposure, efficient conductivity and unique electronic structure of the Co₉S₈/Ni₃S₂ interface, the as-prepared Co₉S₈/Ni₃S₂-NF exhibits efficient electrocatalytic NO-RR performance, including up to 99.0% conversion and 96.0% selectivity towards aniline, and outstanding functional group tolerance. Mechanistic investigations and theoretical calculations reveal that electron transfer from Ni₃S₂ to Co₉S₈ is beneficial for the co-adsorption of H₂O and nitrobenzene molecules at the interfacial sites, promoting the formation of active hydrogen and subsequent reduction of nitrobenzene. Additionally, the interfacial charge transfer breaks the symmetry of two active Co sites at the Co₉S₈/Ni₃S₂ interface, which markedly reduces the energy barrier for reduction of nitrobenzene to aniline. This work offers a successful example for the interfacial engineering of metal sulfide-based heterojunctions with excellent electrocatalytic nitroarene reduction performance, and also paves the way for the in-depth understanding of the corresponding mechanism.

Engineering of Oxide Protected Gold Nanoparticles

Gold nanoparticles that are partially or fully covered by metal oxide shells provide superior functionality and stability for catalytic and plasmonic applications. Yet, facile methods for controlled fabrication of thin oxide layers on metal nanoparticles are lacking. Here, we report an easy method to reliably engineer thin Ga₂O₃ shells on Au nanoparticles, based on liquid-phase chemical oxidation of Au-Ga alloy nanoparticles. We demonstrate that, with this technique, laminar and ultrathin Ga₂O₃ shells can be grown with ranging thickness from sub- to several monolayers. We show how the localized surface plasmon resonance can be used to understand the reaction process and quantitatively monitor the Ga₂O₃ shell growth. Finally, we demonstrate that the Ga₂O₃ coating prevents sintering of the Au nanoparticles, providing thermal stability to at least 250 °C. This approach, building on dealloying of bimetallic nanoparticles by the solution-phase oxidation, promises a general technique for achieving controlled metal/oxide core/shell nanoparticles.

N-Heterocyclic Carbene-Stabilized Ultrasmall Gold Nanoclusters in a Metal-Organic Framework for Photocatalytic CO2 Reduction

Ultrafine gold nanoclusters (Au-NCs) are susceptible to migrate and aggregate, even in the porosity of many crystalline solids. N-heterocyclic carbenes (NHCs) are a class of structurally diverse ligands for the stabilization of Au-NCs in homogeneous chemistry, showing catalytic reactivity in CO₂ activation. Herein, for the first time, we demonstrate a heterogeneous nucleation approach to stabilize ultrasmall and highly dispersed gold nanoclusters in an NHC-functionalized porous matrix. The sizes of gold nanoclusters are tunable from 1.3 nm to 1.8 nm based on the interpenetration of the metal-organic framework (MOF) topology. Control experiments using amine or imidazolium-functionalized MOFs afforded the aggregation of Au species. The resultant Au-NC@MOF composite exhibits a steady and excellent activity in photocatalytic CO₂ reduction, superior to control mixtures without NHC-ligand stabilization. Mechanistic studies reveal the synergistic catalytic effect of MOFs and Au-NCs through the MOF-NHC-Au covalent-bonding bridges.

One-pot synthesis of AuPd@FexOy nanoagent with the activable Fe species for enhanced Chemodynamic-photothermal synergetic therapy

Facile fabrication of Fe-based nanotheranostic agents with the enhanced Chemodynamic therapy (CDT) effect and multiple functions is important for oncotherapy. In this report, noble-metal@Fe_xO_y core-shell nanoparticles (Au@Fe_xO_y NPs, AuRu@Fe_xO_y NPs, AuPt@Fe_xO_y NPs and AuPd@Fe_xO_y NPs) are one-pot constructed by a simply redox self-assembly strategy. As a typical example, AuPd@Fe_xO_y NPs are applied for oncotherapy. Compared to their crystalline counterparts (e.g., AuPd@c-Fe₂O₃ nanocrystals (NCs)), AuPd@Fe_xO_y NPs with the metastable Fe_xO_y shell can be activated by a small amount of NaBH₄ to obviously enhance the production of ·OH in subsequent Fenton reaction (these activated products are termed as r-AuPd@Fe_xO_y NPs). In addition, a favorable photothermal effect (63.5% photothermal conversion efficiency) of r-AuPd@Fe_xO_y NPs can further promote the ·OH generation. Moreover, r-AuPd@Fe_xO_y NPs also show a pH-responsive T₁-weighted MRI contrast property, CT imaging capacity and the function of regulating tumor microenvironment. This work presents an attractive route to prepare versatile nanotheranostic agents.

Engineering of Yolk/Core-Shell Structured Nanoreactors for Thermal Hydrogenations

Heterogeneous hydrogenation reactions are of great importance for chemical upgrading and synthesis, but still face the challenges of controlling selectivity and long-term stability. To improve the catalytic performance, many hydrogenation reactions utilize special yolk/core-shell nanoreactors (YCSNs) with unique architectures and advantageous properties. This work presents the developmental and technological challenges in the preparation of YCSNs that are potentially useful for hydrogenation reactions, and provides a summary of the properties of these materials. The work also addresses the scientific challenges in applications of these YCSNs in various gas and liquid-phase hydrogenation reactions. The catalyst structures, catalytic performance, structure-performance relationships, reaction mechanisms, and unsolved problems are discussed too. Also, a brief outlook and opportunities for future research in this field are presented. This work on the advancements in YCSNs might inspire the creation of new materials with desired structures for achieving maximal hydrogenation performances.

Co–Nx catalyst: an effective catalyst for the transformation of nitro compounds into azo compounds

The selective hydrogenation of nitro compounds into their corresponding azo compounds is challenging in organic synthesis.

Novel Core-Shell (ε-MnO2/CeO2)@CeO2 Composite Catalyst with a Synergistic Effect for Efficient Formaldehyde Oxidation

A novel core-shell (ε-MnO₂/CeO₂)@CeO₂ composite catalyst with a synergistic effect was prepared by hydrothermal reaction and thermal decomposition and its application to high-efficiency oxidation removal of formaldehyde (HCHO) was systemically investigated. The (MnCO₃/CeO₂)@CeO₂ precursor was prepared first by the one-pot hydrothermal reaction of Mn²⁺ and Ce³⁺ solutions with a CO₂-storage material (CO₂SM) without any external templates or surfactants required. The thermal decomposition of the precursor afforded the core-shell (ε-MnO₂/CeO₂)@CeO₂ composite catalyst with excellent catalytic performance. HCHO in the feed gas (180 ppm HCHO, 21% O₂, N₂ balanced) at a gas hourly space velocity of 100 L/(g_cat h) is 100% converted over the catalyst at 80 °C. The conversion rate remains above 95% in 72 h and above 73.8% in 140 h, suggesting the strong stability of the catalyst at high gas flow rates and relatively low temperatures. The synergistic mechanism of the catalyst was explored by X-ray diffraction, Raman, Brunauer-Emmett-Teller, transmission electron microscopy, and X-ray photoelectron spectroscopy. The number of defects in the catalyst and the strength of the Mn-O bond in ε-MnO₂ can be tuned by adjusting the synthesis conditions. More oxygen vacancies on the surface of CeO₂ can make the synergistic effect of the catalyst stronger, which significantly improves the lattice oxygen (O_latt) activity on the surface of ε-MnO₂. Our work has provided new insights into the preparation of the desired composite catalysts with excellent performances.

Role of the Support in Gold-Containing Nanoparticles as Heterogeneous Catalysts

In this review, we discuss selected examples from recent literature on the role of the support on directing the nanostructures of Au-based monometallic and bimetallic nanoparticles. The role of support is then discussed in relation to the catalytic properties of Au-based monometallic and bimetallic nanoparticles using different gas phase and liquid phase reactions. The reactions discussed include CO oxidation, aerobic oxidation of monohydric and polyhydric alcohols, selective hydrogenation of alkynes, hydrogenation of nitroaromatics, CO₂ hydrogenation, C–C coupling, and methane oxidation. Only studies where the role of support has been explicitly studied in detail have been selected for discussion. However, the role of support is also examined using examples of reactions involving unsupported metal nanoparticles (i.e., colloidal nanoparticles). It is clear that the support functionality can play a crucial role in tuning the catalytic activity that is observed and that advanced theory and characterization add greatly to our understanding of these fascinating catalysts.

Potential-tuned selective electrosynthesis of azoxy-, azo- and amino-aromatics over a CoP nanosheet cathode

Azoxy-, azo- and amino-aromatics are among the most widely used building blocks in materials science pharmaceuticals and synthetic chemistry, but their controllable and green synthesis has not yet been well established. Herein, a facile potential-tuned electrosynthesis of azoxy-, azo- and amino-aromatics via aqueous selective reduction of nitroarene feedstocks over a CoP nanosheet cathode is developed. A series of azoxy-, azo- and amino-compounds with excellent selectivity, good functional group tolerance and high yields are produced by applying different bias input. The synthetically significant and challenging asymmetric azoxy-aromatics can be controllably synthesized in moderate to good yields. The use of water as the hydrogen source makes this strategy remarkably fascinating and promising. In addition, deuterated aromatic amines with a high deuterium content can be readily obtained by using D2O. By pairing with anodic oxidation of aliphatic amines to nitriles, synthetically useful building blocks can be simultaneously produced in a CoP||Ni2P two-electrode electrolyzer. Only 1.25 V is required to achieve a current density of 20 mA cm-2, which is much lower than that of overall water splitting (1.70 V). The paired oxidation and reduction reactions can also be driven using a 1.5 V battery to synthesize nitrile and azoxybenzene with good yields and selectivity, further emphasizing the flexibility and controllability of our method. This work paves the way for a promising approach to the green synthesis of valuable chemicals through potential-controlled electrosynthesis.

Core-Shell-Heterostructured Magnetic-Plasmonic Nanoassemblies with Highly Retained Magnetic-Plasmonic Activities for Ultrasensitive Bioanalysis in Complex Matrix

Herein, a facile self-assembly strategy for coassembling oleic acid-coated iron oxide nanoparticles (OC-IONPs) with oleylamine-coated gold nanoparticles (OA-AuNPs) to form colloidal magnetic-plasmonic nanoassemblies (MPNAs) is reported. The resultant MPNAs exhibit a typical core-shell heterostructure comprising aggregated OA-AuNPs as a plasmonic core surrounded by an assembled magnetic shell of OC-IONPs. Owing to the high loading of OA-AuNPs and reasonable spatial distribution of OC-IONPs, the resultant MPNAs exhibit highly retained magnetic-plasmonic activities simultaneously. Using the intrinsic dual functionality of MPNAs as a magnetic separator and a plasmonic signal transducer, it is demonstrated that the assembled MPNAs can achieve the simultaneous magnetic manipulation and optical detection on the lateral flow immunoassay platform after surface functionalization with recognition molecules. In conclusion, the core-shell-heterostructured MPNAs can serve as a nanoanalytical platform for the separation and concentration of target compounds from complex biological samples using magnetic properties and simultaneous optical sensing using plasmonic properties.

A redox interaction-engaged strategy for multicomponent nanomaterials

The review article focuses on the redox interaction-engaged strategy that offers a powerful way to construct multicomponent nanomaterials with precisely-controlled size, shape, composition and hybridization of nanostructures.

Formation of a Pd/MgO Structured Catalyst for the Aqueous Oxidation of Silane to Silanol

The catalytic oxidation of silanes to produce silanols using water as an oxidant at mild temperatures is a major challenge in Si-H activation. Highly efficient and easy-to-recycle catalysts based on Pd nanoparticles are in high demand. In this study, Pd nanoparticles embedded in an MgO porous overlayer on an Mg plate as a structured catalyst was prepared by the plasma electrolyte oxidation (PEO) technique. The Pd/MgO catalyst is strongly anchored to the MgO plate, building a structured catalyst. Fabrication parameters such as the temperature of the electrolyte and applied voltage significantly influenced the structure of the obtained Pd/MgO catalyst and in turn its catalytic activity. The catalytic activities of Pd/MgO were evaluated by activation of a Si-H bond for catalyzing the aqueous oxidation of silanes to silanol at mild temperatures. The catalytic activity of Pd nanoparticles is favored by their electro-deficient state due to influence from the MgO substrate. The Pd/MgO catalyst exhibits good performance stability during recycling. This work paves the way for fabricating structured catalysts with long-term stability and enhanced metal–oxide interaction.

Surface Anchoring Approach for Growth of CeO2 Nanocrystals on Prussian Blue Capsules Enable Superior Lithium Storage

Prussian blue (PB) and its analogues (PBAs) have been acknowledged as promising materials for the catalysis, energy storage, and bioapplications because of different constructions and tunable composition. The approach for surface modification with metal oxides for boosting the performance, however, is rarely reported. Herein, a facile surface anchoring strategy has been proposed to realize CeO₂ nanocrystals uniformly depositing on the surface of PB. Besides, the size, thickness, and depositing density of CeO₂ nanocrystals can be regulated by adjusting the amount of the precursor and the proportion of ethanol and deionized water. Furthermore, after a step of confined pyrolysis treatment under an air atmosphere, CeO₂ nanocrystals with an encapsulated iron oxide structure have been obtained. This shows a remarkable cycling and rate performance when evaluated as an anode of the lithium-ion battery. The surface anchoring approach of the CeO₂ nanocrystals may not only promote the various applications of PB-based materials but also provide an opportunity for developing the architecture of other CeO₂-based core-shell nanostructures.

Control of Catalytic Activity of Nano-Au through Tailoring the Fermi Level of Support

The catalytic properties of nanometals are strongly dependent on their electronic states which, are influenced by the interaction with the supports. However, a precise manipulation of the electronic interaction is lacking, and the nature of the interaction is still ambiguous. Herein, using Au/ZnFe_x Co_{2- x} O₄ (x = 0-2) as a model system with continuously tuned Fermi levels of supports, the electronic structure of the Au catalyst can be precisely controlled by changing the Fermi level of the support, which arises from the charge redistribution between the two phases. A higher Fermi level of ZnFe₂ O₄ support makes nano-Au negatively charged and thus facilitates the oxidation of CO, and in contrast, a lower Fermi level of ZnCo₂ O₄ support makes nano-Au positively charged and is preferential to the oxidation of benzyl alcohol. This work represents a solid step towards exploration of advanced catalysts with deliberate design of electronic structure and catalytic properties.

Tunable bimetallic Au-Pd@CeO2 for semihydrogenation of phenylacetylene by ammonia borane

The fabrication of a bimetallic core and ceria shell nanostructure is considered a promising way to promote catalytic performance and stability. Here, we report an Au-Pd@CeO2 core-shell structure with a tunable Au/Pd ratio through a self-assembly autoredox reaction approach. This process involves the sequence reduction of Au and Pd precursors and then self-assembly of CeO2 nanoparticles to encapsulate the noble metal core. The as-obtained samples exhibit excellent activity and selectivity towards the ammonia borane initiated hydrogenation of phenylacetylene with an enhanced stability owing to the protection from outside CeO2 nanoparticles. Through the construction of an Au-Pd bimetallic structure, an electron modification of Pd due to charge transfer between Au and Pd results in an enhanced catalytic performance. Such a strategy is promising for the synthesis of other bimetallic noble core and ceria shell structures for further applications.

Synthesis of a Highly Stable Pd@CeO2 Catalyst for Methane Combustion with the Synergistic Effect of Urea and Citric Acid

Making use of synergy between urea and citric acid, a core-shell Pd@CeO₂ catalyst with spherical morphology was facilely synthesized by a hydrothermal method. The formation mechanism of the core-shell structure in the presence of citric acid and hydrogen peroxide was studied. Results showed that the Pd@CeO₂ catalyst exhibited high catalytic activity in methane oxidation. Pd nanoparticles were well stabilized by CeO₂ shell encapsulation, resulting in high stability of the catalyst. A high CH₄ conversion of 99% was retained after 50 h on-stream reaction at 500 °C. Additionally, many tiny pores on the CeO₂ shell surface were beneficial for the full contact between reactants and active components. Pd nanoparticles were highly dispersed inside the shell, improving the utilization efficiency of active components. The results also demonstrated that the Pd species in the catalyst existed in the form of oxidation state, mainly in PdO (ca. 66.6%), which played an essential part in methane combustion.

A general one-pot strategy for the synthesis of Au@multi-oxide yolk@shell nanospheres with enhanced catalytic performance

By integrating redox self-assembly and redox etching processes, we report a general one-pot strategy for the synthesis of Au@multi-M x O y (M = Co, Ce, Fe, and Sn) yolk@shell nanospheres. Without any additional protecting molecule or reductant, the whole reaction is a clean redox process that happens among the inorganic metal salts in an alkaline aqueous solution. By using this method, Au@Co3O4/CeO2 (Au@Co-Ce), Au@Co3O4/Fe2O3 (Au@Co-Fe), and Au@CeO2/SnO2 (Au@Ce-Sn) yolk@shell nanospheres with binary oxides as shells, Au@Co3O4/CeO2/Fe2O3 (Au@Co-Ce-Fe) yolk@shell nanospheres with ternary oxides as shells and Au@Co3O4/CeO2/Fe2O3/SnO2 (Au@Co-Ce-Fe-Sn) yolk@shell nanospheres with quaternary oxides as shells can be obtained. Subsequently, the catalytic CO oxidation was selected as the catalytic model, and the Au@Co-Ce system was chosen as the catalyst. It was found that the catalytic activity of Au@Co-Ce yolk@shell nanospheres can be optimized by altering the relative proportion of Co and Ce oxides.