Heterogeneous Hydrogenation with Hydrogen Spillover Enabled by Nitrogen Vacancies on Boron Nitride-Supported Pd Nanoparticles

Heterogeneous hydrogenation with hydrogen spillover has been demonstrated as an effective route to achieve high selectivity towards target products. More effort should be paid to understand the complicated correlation between the nature of supports and hydrogenation involving hydrogen spillover. Herein, we report the development of the hydrogenation system of hexagonal boron nitride (h-BN)-supported Pd nanoparticles for the hydrogenation of aldehydes/ketones to alcohols with hydrogen spillover. Nitrogen vacancies in h-BN determine the feasibility of hydrogen spillover from Pd to h-BN. The hydrogenation of aldehydes/ketones with hydrogen spillover from Pd proceeds on nitrogen vacancies on h-BN. The weak adsorption of alcohols to h-BN inhibits the deep hydrogenation of aldehydes/ketones, thus leading to high catalytic selectivity to alcohols. Moreover, the hydrogen spillover-based hydrogenation mechanism makes the catalyst system exhibit a high tolerance to CO poisoning.     

Modulating the Reaction Configuration by Breaking the Structural Symmetry of Active Sites for Efficient Photocatalytic Reduction of Low-concentration CO2

Photocatalytic conversion of low-concentration CO₂ is considered as a promising way to simultaneously mitigate the environmental and energy issues. However, the weak CO₂ adsorption and tough CO₂ activation process seriously compromise the CO production, due to the chemical inertness of CO₂ molecule and the formed fragile metal-C/O bond. Herein, we designed and fabricated oxygen vacancy contained Co₃O₄ hollow nanoparticles on ordered macroporous N-doped carbon framework (Vo−HCo₃O₄/OMNC) towards photoreduction of low-concentration CO₂. In situ spectra and ab initio molecular dynamics simulations reveal that the constructed oxygen vacancy is able to break the local structural symmetry of Co−O−Co sites. The formation of asymmetric active site switches the CO₂ configuration from a single-site linear model to a multiple-sites bending one with a highly stable configuration, enhancing the binding and structural polarization of CO₂ molecules. As a result, Vo−HCo₃O₄/OMNC shows unprecedent activity in the photocatalytic conversion of low-concentration CO₂ (10 % CO₂/Ar) under laboratory light source or even natural sunlight, affording a syngas yield of 337.8 or 95.2 mmol g⁻¹ h⁻¹, respectively, with an apparent quantum yield up to 4.2 %.     

Selective Electrochemical Hydrogenation of Phenol with Earth-abundant Ni−MoO2 Heterostructured Catalysts: Effect of Oxygen Vacancy on Product Selectivity

Herein, we report highly efficient carbon supported Ni−MoO₂ heterostructured catalysts for the electrochemical hydrogenation (ECH) of phenol in 0.10 M aqueous sulfuric acid (pH 0.7) at 60 °C. Highest yields for cyclohexanol and cyclohexanone of 95 % and 86 % with faradaic efficiencies of ∼50 % are obtained with catalysts bearing high and low densities of oxygen vacancy (O_v) sites, respectively. In situ diffuse reflectance infrared spectroscopy and density functional theory calculations reveal that the enhanced phenol adsorption strength is responsible for the superior catalytic efficiency. Furthermore, 1-cyclohexene-1-ol is an important intermediate. Its hydrogenation route and hence the final product are affected by the O_v density. This work opens a promising avenue to the rational design of advanced electrocatalysts for the upgrading of phenolic compounds.     

Photocatalytic Co-Reduction of N2 and CO2 with CeO2 Catalyst for Urea Synthesis

The effective conversion of carbon dioxide (CO₂) and nitrogen (N₂) into urea by photocatalytic reaction under mild conditions is considered to be a more environmentally friendly and promising alternative strategies. However, the weak adsorption and activation ability of inert gas on photocatalysts has become the main challenge that hinder the advancement of this technique. Herein, we have successfully established mesoporous CeO_2-x nanorods with adjustable oxygen vacancy concentration by heat treatment in Ar/H₂ (90 % : 10 %) atmosphere, enhancing the targeted adsorption and activation of N₂ and CO₂ by introducing oxygen vacancies. Particularly, CeO₂-500 (CeO₂ nanorods heated treatment at 500 °C) revealed high photocatalytic activity toward the C−N coupling reaction for urea synthesis with a remarkable urea yield rate of 15.5 μg/h. Besides, both aberration corrected transmission electron microscopy (AC-TEM) and Fourier transform infrared (FT-IR) spectroscopy were used to research the atomic surface structure of CeO₂-500 at high resolution and to monitor the key intermediate precursors generated. The reaction mechanism of photocatalytic C−N coupling was studied in detail by combining Density Functional Theory (DFT) with specific experiments. We hope this work provides important inspiration and guiding significance towards highly efficient photocatalytic synthesis of urea.     

Exposed Zinc Sites on Hybrid ZnIn2S4@CdS Nanocages for Efficient Regioselective Photocatalytic Epoxide Alcoholysis

Photocatalytic epoxide alcoholysis through C−O bond cleavage and formation has emerged as an alternative to synthesizing anti-tumoral pharmaceuticals and fine chemicals. However, the lack of crucial evidence to interpret the interaction between reactants and photocatalyst surface makes it challenging for photocatalytic epoxide alcoholysis with both high activity and regioselectivity. In this work, we report the hierarchical ZnIn₂S₄@CdS photocatalyst for epoxide alcoholysis with high regioselectivity nearly 100 %. Mechanistic studies unveil that the precise activation switch on exposed Zn acid sites for C−O bond polarization and cleavage has a critical significance for achieving efficient photocatalytic performance. Furthermore, the establishment of Z-scheme heterojunction facilitates the interface charge separation and transfer. Remarkably, the underlying regioselective photocatalytic reaction pathway has been distinctly revealed.     

Gradient Graphdiyne Induced Copper and Oxygen Vacancies in Cu0.95V2O5 Anodes for Fast-Charging Lithium-Ion Batteries

Vacancies can significantly affect the performance of metal oxide materials. Here, a gradient graphdiyne (GDY) induced Cu/O-dual-vacancies abundant Cu_0.95V₂O₅@GDY heterostructure material has been prepared as a competitive fast-charging anode material. Cu_0.95V₂O₅ self-catalyzes the growth of gradient GDY with rich alkyne-alkene complex in the inner layer and rich alkyne bonds in the outer layer, leading to the formation of Cu and O vacancies in Cu_0.95V₂O₅. The synergistic effect of vacancies and gradient GDY results in the electron redistribution at the hetero-interface to drive the generation of a built-in electric field. Thus, the Li-ion transport kinetics, electrochemical reaction reversibility and Li storage sites of Cu_0.95V₂O₅ are greatly enhanced. The Cu_0.95V₂O₅@GDY anodes show excellent fast-charging performance with high capacities and negligible capacity decay for 10 000 cycles and 20 000 cycles at extremely high current densities of 5 A g⁻¹ and 10 A g⁻¹, respectively. Over 30 % of capacity can be delivered in 35 seconds.