Acid-Promoter-Free Ethylene Methoxycarbonylation over Ru-Clusters/Ceria: The Catalysis of Interfacial Lewis Acid–Base Pair

Grain-Boundary-Rich Ceria Metallene Nanozyme with Abundant Metal Site Pairs Boosts Phosphatase-like Activity

Natural phosphatases featuring paired metal sites inspire various advanced nanozymes with phosphatase-like activity as alternatives in practical applications. Numerous efforts to create point defects show limited metal site pairs, further resulting in insufficient activity. However, it remains a grand challenge to accurately engineer abundant metal site pairs in nanozymes. Herein, we report a grain-boundary-rich ceria metallene nanozyme (GB-CeO2) with phosphatase-like activity. Grain boundaries acting as the line or interfacial defects can effectively increase the content of Ce4+/Ce3+ site pairs to 72.28%, achieving a 49.28-fold enhancement in activity. Furthermore, abundant grain boundaries optimize the band structure to assist the photoelectron transfer under irradiation, which further increases the content of metal site pairs to 88.96% and finally realizes a 114.39-fold enhanced activity over that of CeO2 without irradiation. Given the different inhibition effects of pesticides on catalysts with and without irradiation, GB-CeO2 was successfully applied to recognize mixed toxic pesticides.

Electrocatalytic nitrogen reduction to ammonia by atomically precise Cu6 nanoclusters supported on graphene oxide

The electrocatalytic nitrogen reduction reaction (NRR) enables the production of ammonia by the use of renewable energy, providing a direct method for nitrogen fixation. Nevertheless, the NRR process under ambient conditions is often impeded by inertness of N2 and the occurrence of hydrogen evolution as a byproduct in aqueous electrolytes, resulting in a diminished reaction rate and reduced efficiency. In this study, we synthesized Cu6(SMPP)6 nanoclusters (Cu6 NCs for short) and immobilized them on graphene oxide (GO) to investigate their electrocatalytic nitrogen reduction reaction (ENRR) using an H-cell setup. The GO-supported Cu6 NCs exhibit enhanced catalysis with a high NH3 yield rate of 4.8 μg h-1 cm-2 and a high faradaic efficiency up to 30.39% at -1.1 V. Quantum chemistry calculations reveal that the Cu6S6 cluster on GO support facilitates the N2 adsorption and NN bond activation with a surmountable energy barrier for the potential-determining step (N2* → NNH*).

Highly sensitive hydrolytic nanozyme-based sensors for colorimetric detection of aluminum ions

Hydrolytic nanozyme-based visual colorimetry has emerged as a promising strategy for the detection of aluminum ions. However, most studies focus on simulating the structure of natural enzymes while neglecting to regulate the rate of hydrolysis-related steps, leading to low enzyme-like activity for hydrolytic nanozymes. Herein, we constructed a ruthenium dioxide (RuO2) in situ embedded cerium oxide (CeO2) nanozyme (RuO2/CeO2) with a Lewis acid-base pair (Ce-O-Ru-OH), which can simulate the catalytic behavior of phosphatase (PPase) and can be quantitatively quenched by Al3+ to achieve accurate and sensitive Al3+ colorimetric sensing detection. The incorporation of Ru into CeO2 nanorods accelerates the dissociation of H2O, followed by subsequent combination of hydroxide species to Lewis acidic Ce-O sites. This synergistic effect facilitates substrate activation and significantly enhances the hydrolysis activity of the nanozyme. The results show that the RuO2/CeO2 nanozyme exhibits a limit of detection as low as 0.5 ng/mL. We also demonstrate their efficacy in detecting Al3+ in various practical food samples. This study offers novel insights into the advancement of highly sensitive hydrolytic nanozyme engineering for sensing applications.

Influences of Ru and ZrO2 interaction on the hydroesterification of styrene

Interfacial Lewis acid-base pairs are commonly found in ZrO2-supported metal catalysts due to the facile generation of oxygen vacancies of ZrO2. These pairs have been reported to play a crucial role in olefin hydroesterification, especially in the absence of acid promoters and ligands. In this study, a series of ZrO2-supported Ru catalysts with ruthenium(iii) chloride and ruthenium(iii) acetylacetonate as precursors were prepared for the styrene hydroesterification. The catalysts were thoroughly characterized by TPR, TEM, EPR, XPS, and FTIR. The Ru precursors significantly influenced the size and electronic properties of Ru clusters, albeit having minimal impact on oxygen vacancies. Mechanistic studies of styrene hydroesterification over ZrO2-supported Ru catalysts revealed that the carbon monoxide insertion followed the hydrogen transfer step to activated styrene. Higher activity is exhibited over ZrO2-supported Ru catalysts prepared with ruthenium(iii) chloride as a precursor, attributed to the lower adsorption strength of CO over Ru clusters, as evidenced by FTIR and DFT calculations.

Interfacial Metal-Support Interaction and Catalytic Performance of Perovskite LaCrO3-Supported Ru Catalyst

Interfacial metal-support interaction (MSI) significantly affects the dispersion of active metals on the surface of the catalyst support and impacts catalyst performance. Understanding MSI is crucial for developing highly active and stable catalysts with a low metal loading, particularly for noble metal catalysts. In this work, we synthesized LaRuxCr1-xO3 catalysts with low Ru loading (x = 0.005, 0.01, and 0.02) using the sol-gel self-combustion method. We found that all of the Ru atoms immediately above or below the metal-support interface are closely bonded to the perovskite LaCrO3 surface lattice through Ru-O bonds, enhancing the MSI via interfacial reaction and charge transfer mechanisms. We identified a variety of Ru species, including small 3D Ru nanoparticles, 2D dispersed Ru surface atoms, and even 0D Ru single atoms. These highly dispersed Ru species exhibit high activity and stability under dry reforming of methane (DRM) conditions. The LaRu0.01Cr0.99O3 catalyst with very low Ru loading (0.42 wt %) was stable over a 50 h DRM test and the carbon deposition was negligible. The CH4 and CO2 conversions at 750 °C reached 83 and 86%, respectively, approaching the theoretical thermodynamic equilibrium values.

One-Step Hydrothermal/Solvothermal Preparation of Pt/TiO2: An Efficient Catalyst for Biobutanol Oxidation at Room Temperature

The selective oxidation of biobutanol to prepare butyric acid is an important conversion process, but the preparation of low-temperature and efficient catalysts for butanol oxidation is currently a bottleneck problem. In this work, we prepared Pt-TiO2 catalysts with different Pt particle sizes using a simple one-step hydrothermal/solvothermal method. Transmission electron microscopy and X-ray diffraction results showed that the average size of the Pt particles ranged from 1.1 nm to 8.7 nm. Among them, Pt-TiO2 with an average particle size of 3.6 nm exhibited the best catalytic performance for biobutanol. It was capable of almost completely converting butanol, even at room temperature (30 °C), with a 98.9% biobutanol conversion, 98.4% butyric acid selectivity, and a turnover frequency (TOF) of 36 h-1. Increasing the reaction temperature to 80 and 90 °C, the corresponding TOFs increased rapidly to 355 and 619 h-1. The relationship between the electronic structure of Pt and its oxidative performance suggests that the synergistic effect of the dual sites, Pt0 and Pt2+, could be the primary factor contributing to its elevated reactivity.

Identification of a potent palladium-aryldiphosphine catalytic system for high-performance carbonylation of alkenes

The development of stable and efficient ligands is of vital significance to enhance the catalytic performance of carbonylation reactions of alkenes. Herein, an aryldiphosphine ligand (L11) bearing the [Ph2P(ortho-C6H4)]2CH2 skeleton is reported for palladium-catalyzed regioselective carbonylation of alkenes. Compared with the industrially successful Pd/1,2-bis(di-tert-butylphosphinomethyl)benzene catalyst, catalytic efficiency catalyzed by Pd/L11 on methoxycarbonylation of ethylene is obtained, exhibiting better catalytic performance (TON: >2,390,000; TOF: 100,000 h-1; selectivity: >99%) and stronger oxygen-resistance stability. Moreover, a substrate compatibility (122 examples) including chiral and bioactive alkenes or alcohols is achieved with up to 99% yield and 99% regioselectivity. Experimental and computational investigations show that the appropriate bite angle of aryldiphosphine ligand and the favorable interaction of 1,4-dioxane with Pd/L11 synergistically contribute to high activity and selectivity while the electron deficient phosphines originated from electron delocalization endow L11 with excellent oxygen-resistance stability.

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.

Ethylene Methoxycarbonylation over Heterogeneous Pt1/MoS2 Single-Atom Catalyst: Metal-Support Concerted Catalysis

Ethylene methoxycarbonylation (EMC) to methyl propanoate (MP) is an industrially important reaction and commercially uses a homogeneous Pd-phosphine organometallic complex as the catalyst and corrosive strong acid as the promoter. In this work, we develop a Pt1/MoS2 heterogeneous single-atom catalyst (SAC) which exhibits high activity, selectivity, and good recyclability for EMC reaction without need of any liquid acid. The production rate of MP achieves 0.35 gMP gcat-1 h-1 with MP selectivity of 91.1% at 1 MPa CO, 1 MPa C2H4, and 160 °C, which can be doubled at 2 MPa CO and corresponds to 320.1 molMP molPt-1 h-1, at least 1 order of magnitude higher than the earlier reported heterogeneous catalyst and even comparable to some of homogeneous catalyst. Advanced characterizations and DFT calculations reveal that all the Pt single atoms are located at the Mo vacancies along the Mo edge of the MoS2 nanosheets, forming pocket-like Mo-S-Pt1-S-Mo ensembles with uniform and well-defined structure. Methanol is first adsorbed and dissociated on Mo sites, and the produced H spillovers to the adjacent Pt site forming Pt-H species which then activate ethylene, forming Pt-ethyl species. Meanwhile, CO adsorbed on the other Mo site reacts with the Pt-ethyl species, yielding propionyl species, and this carbonylation is the rate-determining step. The final methoxylation step proceeds via the nucleophilic attack of propionyl species by -OCH3 affording the final product MP. Such a metal-support concerted catalysis enabled by the Mo-S-Pt1-S-Mo multisite ensemble opens a new avenue for SACs to promote the multimolecular reactions that prevail in homogeneous catalysis.

Smart Dual-Exsolved Self-Assembled Anode Enables Efficient and Robust Methane-Fueled Solid Oxide Fuel Cells

Perovskite oxides have emerged as alternative anode materials for hydrocarbon-fueled solid oxide fuel cells (SOFCs). Nevertheless, the sluggish kinetics for hydrocarbon conversion hinder their commercial applications. Herein, a novel dual-exsolved self-assembled anode for CH4 -fueled SOFCs is developed. The designed Ru@Ru-Sr2 Fe1.5 Mo0.5 O6-δ (SFM)/Ru-Gd0.1 Ce0.9 O2-δ (GDC) anode exhibits a unique hierarchical structure of nano-heterointerfaces exsolved on submicron skeletons. As a result, the Ru@Ru-SFM/Ru-GDC anode-based single cell achieves high peak power densities of 1.03 and 0.63 W cm-2 at 800 °C under humidified H2 and CH4 , surpassing most reported perovskite-based anodes. Moreover, this anode demonstrates negligible degradation over 200 h in humidified CH4 , indicating high resistance to carbon deposition. Density functional theory calculations reveal that the created metal-oxide heterointerfaces of Ru@Ru-SFM and Ru@Ru-GDC have higher intrinsic activities for CH4 conversion compared to pristine SFM. These findings highlight a viable design of the dual-exsolved self-assembled anode for efficient and robust hydrocarbon-fueled SOFCs.

Targeted NO Oxidation and Synchronous NO2 Inhibition via Oriented 1O2 Formation Based on Lewis Acid Site Adjustment

An appealing strategy for ensuring environmental benefits of the photocatalytic NO oxidation reaction is to convert NO into NO3- instead of NO2, yet the selectivity of products remains challenging. Here, such a scenario could be realized by tailoring the exposure of Lewis acid sites on the surface of ZrO2, aiming to precisely regulate the ROS evolution process for the selective oxidation of NO into NO3-. As evidenced by highly combined experimental characterizations and density functional theory (DFT) simulations, Lewis acid sites serving as electron acceptors could induce itinerant electron redistribution, charge-carrier transfer, and further oxidation of •O2-, which promotes the oriented formation of 1O2. As a result, monoclinic ZrO2 with more Lewis acid sites exhibited an outstanding NO conversion efficiency (56.33%) and extremely low NO2 selectivity (5.04%). The ROS-based reaction process and promotion mechanism of photocatalytic performance have been revealed on the basis of ESR analysis, ROS-quenching experiments, and in situ ROS-quenching DRIFTS. This work could provide a critical view toward oriented ROS formation and advance a unique mechanism of selective NO oxidation into NO3-.

Highly Selective Activation of C-H Bond and Inhibition of C-C Bond Cleavage by Tuning Strong Oxidative Pd Sites

Improving the product selectivity meanwhile restraining deep oxidation still remains a great challenge over the supported Pd-based catalysts. Herein, we demonstrate a universal strategy where the surface strong oxidative Pd sites are partially covered by the transition metal (e. g., Cu, Co, Ni, and Mn) oxide through thermal treatment of alloys. It could effectively inhibit the deep oxidation of isopropanol and achieve the ultrahigh selectivity (>98%) to the target product acetone in a wide temperature range of 50-200 °C, even at 150-200 °C with almost 100% isopropanol conversion over PdCu_1.2/Al₂O₃, while an obvious decline in acetone selectivity is observed from 150 °C over Pd/Al₂O₃. Furthermore, it greatly improves the low-temperature catalytic activity (acetone formation rate at 110 °C over PdCu_1.2/Al₂O₃, 34.1 times higher than that over Pd/Al₂O₃). The decrease of surface Pd site exposure weakens the cleavage for the C-C bond, while the introduction of proper CuO shifts the d-band center (ε_d) of Pd upward and strengthens the adsorption and activation of reactants, providing more reactive oxygen species, especially the key super oxygen species (O₂^-) for selective oxidation, and significantly reducing the barrier of O-H and β-C-H bond scission. The molecular-level understanding of the C-H and C-C bond scission mechanism will guide the regulation of strong oxidative noble metal sites with relatively inert metal oxide for the other selective catalytic oxidation reactions.

Switching Amine Oxidation from Imines to Nitriles by Carbon-Hydrogen Bond Activation via Strong Base Modified Strategy

Precisely controlling the product selectivity from the complex reaction is always an attractive topic in the catalysis field. In this paper, the Ru/strong base junction formed by the redox strategy was demonstrated as an efficient catalyst to switch the selectivity in aerobic oxidation of benzylamines. The zirconia-supported ruthenium (Ru-ZrO₂) catalyst could catalyze benzylamine oxidation coupling to imines; however, the potassium oxide strong base modified zirconia-supported ruthenium (Ru-K-ZrO₂) catalyst could catalyze benzylamine oxidation dehydrogenation to nitriles. Insight into the mechanism showed that the base modified catalyst had excellent dehydrogenation ability which was assisted by the C-H bond activation and changed the reaction pathway. The strong base modified strategy may provide a new approach for controlling the performance of heterogeneous catalysts and product selectivity.

Insights into Chlorobenzene Catalytic Oxidation over Noble Metal Loading {001}-TiO2: The Role of NaBH4 and Subnanometer Ru Undergoing Stable Ru0Ru4+ Circulation

Catalytic combustion of ubiquitous chlorinated volatile organic compounds (CVOCs) encounters bottlenecks regarding catalyst deactivation by chlorine poisoning and generation of toxic polychlorinated byproducts. Herein, Ru, Pd, and Rh were loaded on {001}-TiO₂ for thermal catalytic oxidation of chlorobenzene (CB), with Ru/{001}-TiO₂ representing superior reactivity, CO₂ selectivity, and stability in the 1000 min on-stream test. Interestingly, both acid sites and reactive active oxygen species (ROS) were remarkably promoted via adding NaBH₄. But merely enhancing these active sites of the catalyst in CVOC treatment is insufficient. Continuous deep oxidation of CB with effective Cl desorption is also a core issue successfully tackled through the steady Ru⁰↔Ru⁴⁺ circulation. This circulation was facilitated by the observed higher subnanometer Ru dispersion on {001}-TiO₂ than the other two noble metals that was supported by single atom stability DFT calculation. Nearly 88 degradation products in off-gas were detected, with Ru/{001}-TiO₂ producing the lowest polychlorinated benzene byproducts. An effective and sustainable CB degradation mechanism boosted by the cooperation of NaBH₄ enhanced active sites and Ru circulation was proposed accordingly. Insights gained from this study open a new avenue to the rational design of promising catalysts for the treatment of CVOCs.

Metal-Acid Bifunctional Catalysts toward Tandem Reaction: One-Step Hydroalkylation of Benzene to Cyclohexylbenzene

The one-step hydroalkylation of benzene to cyclohexylbenzene (CHB) is a technically challenging and economically interesting reaction with great industrial importance, where bifunctional catalysts play a crucial role in such a tandem reaction. In this work, we report H₃PW₁₂O₄₀ (HPW) modified Ni nanoparticles (NPs) supported on mixed metal oxides (Ni/MMOs), which are featured by HPW species localized on the surface of Ni NPs (denoted as HPW-Ni/MMOs). The optimal catalyst (0.3HPW-Ni/MMOs) exhibits a satisfactory catalytic performance toward benzene hydroalkylation to CHB with a CHB yield of up to 41.2%, which is the highest standard among previously reported catalysts to date. A combination investigation based on HR-TEM, XPS, XANES, and in situ FT-IR verified the electron transfer from the W atom to the adjacent Ni atom, which facilitated the formation and desorption of cyclohexene (CHE) from Ni followed by the alkylation reaction of benzene and CHE at the interfacial Brønsted (B) acid sites of HPW, accounting for the significantly enhanced catalytic behavior. It is proposed that the HPW-Ni interface structure in xHPW-Ni/MMOs samples provides unique adsorption sites for benzene and CHE with a moderate adsorption strength, which serve as the intrinsic active center for this reaction: the Ni site promotes the hydrogenation of benzene to CHE, while the B acid site in HPW facilitates the alkylation of CHE and benzene to produce CHB. This work provides a fundamental understanding of the metal-acid synergistic catalysis toward the hydroalkylation reaction, which can be extended to the design and preparation of high-performance catalysts used in tandem reactions.

Iodine-Modified Pd Catalysts Promote the Bifunctional Catalytic Synthesis of 2,5-Hexanedione from C6 Furan Aldehydes

Currently, low intimacy between hydrogenation sites and acidic sites causes unsatisfactory catalytic activity and selectivity for the synthesis of 2,5-hexanedione from C₆ furan aldehydes (5-methylfurfural, 5-hydroxymethylfurfural). Herein, iodine(I) modification of Pd-supported catalysts (such as PdI/Al₂ O₃ and PdI/SiO₂ ) was investigated to modulate the hydrogenation sites and acidic sites. Unlike Pd catalysts that produced 71.4 % yield of 2-hydroxymethyl-5-methyl tetrahydrofuran via an overhydrogenation route of 5-methylfurfural, PdI catalysts showed a high efficiency for 2,5-hexanedione with 93.7 % yield by a hydrogenative ring-opening route. More importantly, the selective synthesis of 2,5-hexanedione from 5-hydroxymethylfurfural with a high yield of 50.2 % by the hydrogenolysis and subsequent ring-opening route was reported for the first time. I-modified Pd nanoparticles produced in-situ hydrogen spillover, which promoted the selective C=O hydrogenation and ring-opening steps by regulating the adsorption configuration of the reactants and the transformation of Lewis to Brønsted acidity, respectively.

Synergy in Au-CuO Janus Structure for Catalytic Isopropanol Oxidative Dehydrogenation to Acetone

The controlled oxidation of alcohols to the corresponding ketones or aldehydes via selective cleavage of the β-C-H bond of alcohols under mild conditions still remains a significant challenge. Although the metal/oxide interface is highly active and selective, the interfacial sites fall far behind the demand, due to the large and thick support. Herein, we successfully develop a unique Au-CuO Janus structure (average particle size=3.8 nm) with an ultrathin CuO layer (0.5 nm thickness) via a bimetal in situ activation and separation strategy. The resulting Au-CuO interfacial sites prominently enhance isopropanol adsorption and decrease the energy barrier of β-C-H bond scission from 1.44 to 0.01 eV due to the strong affinity between the O atom of CuO and the H atom of isopropanol, compared with Au sites alone, thereby achieving ultrahigh acetone selectivity (99.3 %) over 1.1 wt % AuCu_0.75 /Al₂ O₃ at 100 °C and atmospheric pressure with 97.5 % isopropanol conversion. Furthermore, Au-CuO Janus structures supported on SiO₂ , TiO₂ or CeO₂ exhibit remarkable catalytic performance, and great promotion in activity and acetone selectivity is achieved as well for other reducible oxides derived from Fe, Co, Ni and Mn. This study should help to develop strategies for maximized interfacial site construction and structure optimization for efficient β-C-H bond activation.

Steering the reaction pathway of syngas-to-light olefins with coordination unsaturated sites of ZnGaOx spinel

Significant progress has been demonstrated in the development of bifunctional oxide-zeolite catalyst concept to tackle the selectivity challenge in syngas chemistry. Despite general recognition on the importance of defect sites of metal oxides for CO/H₂ activation, the actual structure and catalytic roles are far from being well understood. We demonstrate here that syngas conversion can be steered along a highly active and selective pathway towards light olefins via ketene-acetate (acetyl) intermediates by the surface with coordination unsaturated metal species, oxygen vacancies and zinc vacancies over ZnGaO_x spinel-SAPO-34 composites. It gives 75.6% light-olefins selectivity and 49.5% CO conversion. By contrast, spinel-SAPO-34 containing only a small amount of oxygen vacancies and zinc vacancies gives only 14.9% light olefins selectivity at 6.6% CO conversion under the same condition. These findings reveal the importance to tailor the structure of metal oxides with coordination unsaturated metal sites/oxygen vacancies in selectivity control within the oxide-zeolite framework for syngas conversion and being anticipated also for CO₂ hydrogenation.

Boosting Energy Efficiency and Stability of Li-CO2 Batteries via Synergy between Ru Atom Clusters and Single-Atom Ru-N4 sites in the Electrocatalyst Cathode

The Li-CO₂ battery is a novel strategy for CO₂ capture and energy-storage applications. However, the sluggish CO₂ reduction and evolution reactions cause large overpotential and poor cycling performance. Herein, a new catalyst containing well-defined ruthenium (Ru) atomic clusters (Ru_AC ) and single-atom Ru-N₄ (Ru_SA ) composite sites on carbon nanobox substrate (Ru_AC+SA @NCB) (NCB = nitrogen-doped carbon nanobox) is fabricated by utilizing the different complexation effects between the Ru cation and the amine group (NH₂ ) on carbon quantum dots or nitrogen moieties on NCB. Systematic experimental and theoretical investigations demonstrate the vital role of electronic synergy between Ru_AC and Ru-N₄ in improving the electrocatalytic activity toward the CO₂ evolution reaction (CO₂ ER) and CO₂ reduction reaction (CO₂ RR). The electronic properties of the Ru-N₄ sites are essentially modulated by the adjacent Ru_AC species, which optimizes the interactions with key reaction intermediates thereby reducing the energy barriers in the rate-determining steps of the CO₂ RR and CO₂ ER. Remarkably, the Ru_AC+SA @NCB-based cell displays unprecedented overpotentials as low as 1.65 and 1.86 V at ultrahigh rates of 1 and 2 A g^-1 , and twofold cycling lifespan than the baselines. The findings provide a novel strategy to construct catalysts with composite active sites comprising multiple atom assemblies for high-performance metal-CO₂ batteries.

The bifunctional Lewis acid site improved reactive oxygen species production: a detailed study of surface acid site modulation of TiO2 using ethanol and Br−

Modulation of surface acid sites (SAS) can effectively enhance the efficiency of reactive oxygen species (ROS) production.

Dual Active Centers Bridged by Oxygen Vacancies of Ru Single Atoms Hybrids Supported on Molybdenum Oxide for Photocatalytic Ammonia Synthesis

Photocatalytic synthesis of ammonia (NH 3 ) holds significant potential compared with the Haber-Bosch process. However, the reported photocatalysts suffered from low efficiency owing to localized electrons deficiency. Here, Ru-SA (single atoms)/H x MoO 3-y hybrids with abundant of Mo n+ (n < 6) species neighboring oxygen vacancies (O V ) are synthesized via a H-spillover process. Detailed characterizations demonstrate that Ru-SA/H x MoO 3 y hybrids can quantitatively produce NH 3 from N 2 and H 2 by the synergetic effect of dual active centers (Ru SA and Mo n+ ). That is, Ru SA boost the activation and migration of H 2 , and Mo n+ species act as the trapping sites of localized electrons and the adsorption and dissociation sites of N 2 , finally leading to NH 3 synthesis on Mo n+ -OH. The NH 3 generation rate is as high as 4.0 mmol h -1 g -1 , accompanied by an apparent quantum efficiency over 6.0% at 650 nm. Our finding may open up a new strategy for acquiring a better NH 3 synthesis approach under mild conditions.

ZrO2/CeO2/polyacrylic acid nanocomposites with alkaline phosphatase-like activity for sensing

In the present work, we synthesized ZrO₂/CeO₂/polyacrylic acid (PAA) nanocomposites (nanozyme) with phosphatase-like activity. ZrO₂ evenly distributed in CeO₂ nanorods considered as lewis acids to enhance the phosphatase-like activity of CeO₂ nanorods. Furthermore, PAA was used to coat ZrO₂/CeO₂/ nanorods and improve the dispersion, stability and robustness. The ZrO₂/CeO₂/PAA nanocomposites had 100% enhanced phosphatase-like activity compared with CeO₂ nanorods and excellent adaptability in a wide pH range from 4.0 to 12.0. ZrO₂/CeO₂/PAA nanocomposites could hydrolyze methyl parathion (MP) to p-nitrophenol (p-NP) with bright yellow color for colorimetric detection. The developed colorimetric detection system showed a linear response from 7.60 × 10^-11-7.60 × 10^-8 M with a detection limit of 0.021 nM and was successfully applied for the determination of MP in corn samples.

Highly selective synthesis of primary amines from amide over Ru-Nb2 O5 catalysts

Amines are an important class of compounds in natural products and medicines. The universal availability of amides provides a potential way for the synthesis of amines. Herein, Ru/Nb₂ O₅ catalyst is demonstrated to be highly efficient and stable for the selective hydrogenation of propionamide to propylamine (as a model reaction), with up to 91.4% yield of propylamine under relatively mild conditions. Results from XPS analyses, CO chemisorption, TEM images and DRIFTS spectra revealed that the unique properties of Nb₂ O₅ can effectively activate the C=O group of amides, and the smaller Ru particles on Nb₂ O₅ could further promote the activation, leading to superior catalytic performance of Ru/Nb₂ O₅ for amide hydrogenation. Meanwhile, reducing the surface acidity of Nb₂ O₅ can greatly inhibit the side reactions to by-products, and further enhance the selectivity to amine. Moreover, this catalytic system is also applicable for the hydrogenation of a variety of amides and provides high potential for the industrial production of primary amines from amides.

High Selectivity to HCl for the Catalytic Removal of 1,2-Dichloroethane Over RuP/3DOM WOx: Insights into the Effects of P-Doping and H2O Introduction

Ru-based catalysts for catalytic combustion of high-toxicity Cl-containing volatile organic compounds are inclined to produce Cl₂ instead of ideal HCl due to the Deacon reaction. We herein reported that the three-dimensionally ordered macroporous (3DOM) WO_x-supported RuP nanocatalyst greatly improved HCl selectivity (at 400 °C, increased from 66.0% over Ru/3DOM WO_x to 96.4% over RuP/3DOM WO_x) and reduced chlorine-containing byproducts for 1,2-dichloroethane (1,2-DCE) oxidation. P-doping enhanced the number of structural hydroxyl groups and Brønsted acid sites. The isotopic 1,2-DCE temperature-programmed desorption experiment in the presence of H₂¹⁸O indicated the generation of a new active oxygen species ¹⁶O¹⁸O that participated in the reaction. Generally, P-doping and H₂O introduction could promote the exchange reaction between Cl and hydroxyl groups, rather than oxygen defects, and then benefit the production of HCl and reduce the generation of other chlorine species or Cl₂, via the reaction processes of C₂H₃Cl → alcohol → aldehyde → carboxylic acids.

Recent Progress of Metal Nanoparticle Catalysts for C–C Bond Forming Reactions

Over the past few decades, the use of transition metal nanoparticles (NPs) in catalysis has attracted much attention and their use in C–C bond forming reactions constitutes one of their most important applications. A huge variety of metal NPs, which have showed high catalytic activity for C–C bond forming reactions, have been developed up to now. Many kinds of stabilizers, such as inorganic materials, magnetically recoverable materials, porous materials, organic–inorganic composites, carbon materials, polymers, and surfactants have been utilized to develop metal NPs catalysts. This review classified and outlined the categories of metal NPs by the type of support.

Oxygen Vacancies and Lewis Acid Sites Synergistically Promoted Catalytic Methane Combustion over Perovskite Oxides

An in-depth understanding of the surface properties-activity relationship could provide a fundamental guidance for the design of highly efficient perovskite-based catalysts for the control of anthropogenic methane emission. Herein, both oxygen vacancies and Coⁿ⁺ Lewis acid sites were purposely introduced on ordered macroporous La_0.8Sr_0.2CoO₃ monolithic catalysts by one-step reduction and selective etching in oxalic acid, and their synergistic effect on methane combustion was investigated. Combined with experimental and theoretical investigations, we revealed that the positively charged Coⁿ⁺ Lewis acid sites and single-electron-trapped oxygen vacancies (Vo·) formed an active pair, which enabled an effective localized electron cloud shift from Vo· to Coⁿ⁺. The characteristic electronic effect modulates surface electronic properties and coordination structures, thus resulting in superior oxygen activation capacity, lattice oxygen mobility, and reducibility, as well as favorable CH₄ interaction and oxidation. Our work not only gives insights into surface properties-activity relationships on perovskite for hydrocarbon combustion but also sheds substantial light on future environmental catalyst design and modulation for hydrocarbon pollutants elimination.

The effect of Cu dopants on electron transfer to O2 and the connection with acetone photocatalytic oxidations over nano-TiO2

Modifying TiO₂ with the Cu element has been shown to be useful for photocatalysis. Although it had been known that Cu species could trap electrons from TiO₂, whether they can affect the kinetics of electron transfer and how this can contribute to photocatalysis still remain unknown. In the current research, Cu-TiO₂ samples were firstly prepared with a hydrothermal reaction and characterized in detail. It was shown that Cu elements were doped in the TiO₂ lattice in +1/0 valence states and have a minor effect on the TiO₂ structure. By means of photoconductances, it is shown that the Cu dopants could catalyze the electron transfer from TiO₂ to O₂ by reducing the apparent activation energy (E_app) by about 2 times. The photocatalytic experiments conducted at different temperatures showed that the E_app of the acetone photocatalytic oxidations could be decreased by ∼2 times; this implies that the Cu dopants change the photocatalytic pathway. First-principles computation showed that the surface Cu dopants, along with the compensated oxygen vacancies, can mediate both of the electron and hole transfer. By combining other studies, we proposed that the Cu sites could act as Lewis acid and base pairs that could combine with acetone and O₂ molecules under UV light illumination; this allows electron transfer to O₂via the Cu sites that then react with acetone. As compared to pure TiO₂ surfaces, the different chemical environment of the Cu sites leads to the decrease in the E_app of photocatalysis.

Facile Fabrication of CeO2-Al2O3 Hollow Sphere with Atomically Dispersed Fe via Spray Pyrolysis

A facile spray pyrolysis method is introduced to construct the hollow CeO₂-Al₂O₃ spheres with atomically dispersed Fe. Only nitrates and ethanol were involved during the one-step preparation process using the ultrasound spray pyrolysis approach. Detailed explorations demonstrated that differences in the pyrolysis temperature of the precursors and heat transfer are crucial to the formation of the hollow nanostructure. In addition, iron species were in situ atomically dispersed on the as-formed CeO₂-Al₂O₃ hollow spheres via this strategy, which demonstrated promising potential in transferring syn-gas to valuable gasoline products.

Synergetic effects of hydrogenation and acidic sites in phosphorus-modified nickel catalysts for the selective conversion of furfural to cyclopentanone

Nickel phosphide species can tailor the selectivity of hydrogenation sites. The yields of CPO and CPL reached 93.5% over 15%Ni–25%P/Al₂O₃. The balanced distribution of hydrogenation/acid sites maximizes the yield of CPO.