Highly Dispersed RuOOH Nanoparticles on Silica Spheres:An Efficient Photothermal Catalyst for Selective Aerobic Oxidation of Benzyl Alcohol

Photothermal catalysis represents a promising strategy to utilize the renewable energy source(e.g.,solar energy)to drive chemical reactions more efficiently.Successful and efficient photothermal catalysis relies on the availability of ideal photothermal catalysts,which can provide both large areas of catalytically active surface and strong light absorption power simultaneously.Such duplex requirements of a photothermal catalyst exhibit opposing dependence on the size of the catalyst nanoparticles,i.e.,smaller size is beneficial for achieving higher surface area and more active surface,whereas larger size favors the light absorption in the nanoparticles.In this article,we report the synthesis of ultrafine RuOOH nanoparticles with a size of 2–3 nm uniformly dispersed on the surfaces of silica(SiOx)nanospheres of hundreds of nanometers in size to tackle this challenge of forming an ideal photothermal catalyst.The ultrasmall RuOOH nanoparticles exhibit a large surface area as well as the ability to activate adsorbed molecular oxygen.The SiOx nanospheres exhibit strong surface light scattering resonances to enhance the light absorption power of the small RuOOH nanoparticles anchored on the SiOx surface.Therefore,the RuOOH/SiOx composite particles represent a new class of efficient photothermal catalysts with a photothermal energy conversion efficiency of 92.5%for selective aerobic oxidation of benzyl alcohol to benzylaldehyde under ambient conditions.     

Constructing an Adaptive Heterojunction as a Highly Active Catalyst for the Oxygen Evolution Reaction

Electrochemical water splitting is of prime importance to green energy technology. Particularly, the reaction at the anode side, namely the oxygen evolution reaction (OER), requires a high overpotential associated with O O bond formation, which dominates the energy-efficiency of the whole process. Activating the anionic redox chemistry of oxygen in metal oxides, which involves the formation of superoxo/peroxo-like (O₂)ⁿ⁻, commonly occurs in most highly active catalysts during the OER process. In this study, a highly active catalyst is designed: electrochemically delithiated LiNiO₂, which facilitates the formation of superoxo/peroxo-like (O₂)ⁿ⁻ species, i.e., NiOO*, for enhancing OER activity. The OER-induced surface reconstruction builds an adaptive heterojunction, where NiOOH grows on delithiated LiNiO₂ (delithiated-LiNiO₂/NiOOH). At this junction, the lithium vacancies within the delithiated LiNiO₂ optimize the electronic structure of the surface NiOOH to form stable NiOO* species, which enables better OER activity. This finding provides new insight for designing highly active catalysts with stable superoxo-like/peroxo-like (O₂)ⁿ⁻ for water oxidation.     

Engineering the Metal/Oxide Interface of Pd Nanowire@CuOx Electrocatalysts for Efficient Alcohol Oxidation Reaction

The development of new type electrocatalysts with promising activity and antipoisoning ability is of great importance for electrocatalysis on alcohol oxidation. In this work, Pd nanowire (PdNW)/CuO_x heterogeneous catalysts with different types of Pd? O? Cu interfaces (Pd/amorphous or crystalline CuO_x) are prepared via a two‐step hydrothermal strategy followed by an air plasma treatment. Their interface‐dependent performance on methanol and ethanol oxidation reaction (MOR and EOR) is clearly observed. The as‐prepared PdNW/crystalline CuO_x catalyst with 17.2 at% of Cu on the PdNW surface exhibits better MOR and EOR activity and stability, compared with that of PdNW/amorphous CuO_x and pristine PdNW catalysts. Significantly, both the cycling tests and the chronoamperometric measurements reveal that the PdNW/crystalline CuO_x catalyst yields excellent tolerance toward the possible intermediates including formaldehyde, formic acid, potassium carbonate, and carbon monoxide generated during the MOR process. The detailed analysis of their chemical state reveals that the enhanced activity and antipoison ability of the PdNW/crystalline CuO_x catalyst originates from the electron‐deficient Pd^δ+ active sites which gradually turn into Pd₅O₄ species during the MOR catalysis. The Pd₅O₄ species can likely be stabilized by moderate crystalline CuO_x decorated on the surface of PdNW due to the strong Pd? O? Cu interaction.     

钯催化剂对锂空气电池氧析出和氧还原反应的催化机理的研究

锂空气电池以其超高的能量密度而备受关注, 然而充、放电过电位高等问题严重限制了其实际应用。金属钯作为催化剂可而降低锂空气电池的充、放电过电位, 但其充、放电反应催化机制尚不完善。本研究运用第一原理计算方法, 建立了钯/氧气/过氧化锂(Pd/O₂/Li₂O₂)的三相界面催化模型, 从微观角度揭示钯催化剂在锂空气电池充、放电反应中的催化机制。研究表明, Pd/O基底通过促进Li₂O₂在界面处的电荷转移提高自身对LiO₂吸附作用, 从而加速放电产物在电极表面的形成, 有效降低了充电过电位0.43 V。     

环境友好的固定床烃类晶格氧选择氧化技术

以正丁烷选择氧化制顺丁烯二酸酐为例，说明按照氧化还原进行的烃类选择氧化反应，采用将催化循环的不同步骤在空间或时间上分离的强制周期操作方法，可大幅度提高反应的选择性，改进环境工效，实现环境友好。重点介绍了强制周期操作的固定床反应技术在烃类选择氧化反应中的应用。     

Promoted Glycerol Oxidation Reaction in an Interface‐Confined Hierarchically Structured Catalyst

Confined catalysis in a 2D system is of particular interest owing to the facet control of the catalysts and the anisotropic kinetics of reactants, which suppress side reactions and improve selectivity. Here, a 2D‐confined system consisting of intercalated Pt nanosheets within few‐layered graphene is demonstrated. The strong metal–substrate interaction between the Pt nanosheets and the graphene leads to the quasi‐2D growth of Pt with a unique (100)/(111)/(100) faceted structure, thus providing excellent catalytic activity and selectivity toward one‐carbon (C1) products for the glycerol oxidation reaction. A hierarchically porous graphene architecture, grown on carbon cloth, is used to fabricate the confined catalyst bed in order to enhance the mass‐diffusion limitation in interface‐confined reactions. Owing to its unique 3D porous structure, this graphene‐confined Pt catalyst exhibits an extraordinary mass activity of 2910 mA mg_Pt ^?1 together with a formate selectivity of 79% at 60 °C. This paves the way toward rational designs of heterogeneous catalysts for energy‐related applications.     

NiS/Cd0.6Zn0.4S Schottky Junction Bifunctional Photocatalyst for Sunlight-Driven Highly Selective Catalytic Oxidation of Vanillyl Alcohol Towards Vanillin Coupled with Hydrogen Evolution Reaction

Selective oxidation of biomass-based molecules to high-value chemicals in conjunction with hydrogen evolution reaction (HER) is an innovative photocatalysis strategy. The key challenge is to design bifunctional photocatalysts with suitable band structures, which can achieve highly efficient generation of high-value chemicals and hydrogen. Herein, NiS/Cd_0.6Zn_0.4S Schottky junction bifunctional catalysts are constructed for sunlight-driven catalytic vanillyl alcohol (VAL) selective oxidation towards vanillin (VN) coupling HER. At optimal conditions, the 8% NiS/Cd_0.6Zn_0.4S photocatalyst achieves high activity of VN production (3.75 mmol g⁻¹ h⁻¹) and HER (3.84 mmol g⁻¹ h⁻¹). It also exhibits remarkable VAL conversion (66.9%), VN yield (52.1%), and selectivity (77.8%). The photocatalytic oxidation of VAL proceeds a carbon-centered radical mechanism via the cleavage of α_C–H bond. Experimental results and theoretical calculations show that NiS with metallic properties enhances the electron transfer capability. Importantly, a Ni-S-Cd “electron bridge” formed at the interface of NiS/Cd_0.6Zn_0.4S further improves the separation/transfer of electrone/h⁺ pairs and also furnishes HER active sites due to its smaller the |ΔG_H*| value, thereby resulting in a remarkably HER activity. This work sheds new light on the selective catalytic oxidation VAL to VN coupling HER, with a new pathway towards achieving its efficient HER efficiency.     

Nanoporous and Highly Active Silicon Carbide Supported CeO2‐Catalysts for the Methane Oxidation Reaction

CeO_x@SiO₂ nanoparticles are used for the first time for the generation of porous SiC materials with tailored pore diameter in the mesopore range containing encapsulated and catalytically active CeO₂ nanoparticles. The nanocasting approach with a preceramic polymer and subsequent pyrolysis is performed at 1300 °C, selective leaching of the siliceous part results in CeO_x/SiC catalysts with remarkable characteristics like monodisperse, spherical pores and specific surface areas of up to 438 m²·g^?1. Porous SiC materials are promising supports for high temperature applications. The catalysts show excellent activities in the oxidation of methane with onset temperatures of the reaction 270 K below the onset of the homogeneous reaction. The synthesis scheme using core‐shell particles is suited to functionalize silicon carbide with a high degree of stabilization of the active nanoparticles against sintering in the core of the template even at pyrolysis temperatures of 1300 °C rendering the novel synthesis principle as an attractive approach for a wide range of catalytic reactions.     

3D Gold‐Modified Cerium and Cobalt Oxide Catalyst on a Graphene Aerogel for Highly Efficient Catalytic Formaldehyde Oxidation

A hard template method is used to prepare porous gold‐doped cerium and cobalt oxide (Au‐Ce_xCo_y) materials. A series of 3D Au‐Ce _xCo_y/graphene aerogel (GA) composites is then fabricated by a facile heating method. The obtained catalysts possess a well‐defined structure of ordered arrays of nanotubes and good performance in formaldehyde (HCHO) oxidation. The composition and surface elemental valence states of the catalysts are modulated by the Ce/Co molar ratio. The Au‐Ce_xCo_y catalyst and graphene oxide sheets are well compounded within 60 s through a diamine cross‐linker to form 3D Au‐Ce_xCo_y/GA composites. In addition, the resulting catalyst of 3 wt% Au‐Ce₃Co/GA achieves ≈55% conversion at room temperature and 100% conversion when the reaction temperature is raised at 60 °C. The synergistic effect between CeO₂ and Co₃O₄ promotes the migration of oxygen species and the activation of Au, which facilitates HCHO oxidation. The method used to prepare the 3D catalyst could be used to produce other catalytic materials with good replication of the template. In addition, these findings provide a simple method for rapid fabrication of catalyst/GA composites. The superior activity and stability of the 3D Au‐Ce₃Co/GA catalyst make it potentially applicable in HCHO removal.     

Perforated Pd Nanosheets with Crystalline/Amorphous Heterostructures as a Highly Active Robust Catalyst toward Formic Acid Oxidation

Perforated ultrathin Pd nanosheets with crystalline/amorphous heterostructures are rationally synthesized to offer a large electrochemically active surface area of 172.6 m² g^?1 and deliver a 5.6 times higher apparent reaction rate in comparison to commercial Pd/C, thus offering a facile confined growth method to generate superior catalysts.     

碳气凝胶载铂催化剂对甲醇的电催化氧化性能

以用溶胶凝胶法制备的碳气凝胶(CA)作为催化剂载体,用间歇微波法制备了碳气凝胶载铂催化剂。用电感耦合等离子光谱仪(ICP)测定了催化剂中Pt的含量,用透射电镜(TEM)和X射线衍射(XRD)对催化剂的形貌、粒径分布以及颗粒粒度进行了表征。结果表明,碳气凝胶载铂催化剂粒子分布均匀、粒径集中,平均粒经为4 nm.用能量散射X射线能谱(EDX)分析了催化剂的化学成分,用循环伏安法、线形扫描伏安法和计时电流法对催化剂的电化学性能进行了表征.结果表明,以碳气凝胶为载体的催化剂比以活性炭为载体的催化剂具有更高的催化活性。     

含钯羟基磷灰石的表征及其对苯甲醇的绿色催化氧化性能研究

采用简单的离子交换法, 将Pd2+与羟基磷灰石中的Ca2+交换, 制备出含钯羟基磷灰石催化剂, 并应用于苯甲醇的绿色催化氧化反应. 通过X射线衍射(XRD)、电感耦合等离子体发射光谱(ICP-AES)、X射线光电子能谱(XPS)、场发射扫描电镜(FE-SEM)以及场发射透射电镜(FE-TEM)等手段对催化剂进行表征, 结果表明, 部分Pd进入羟基磷灰石晶格, 但未改变羟基磷灰石的晶体结构, 部分Pd以纳米颗粒的形式在HAp晶体表面析出. Pd纳米颗粒在催化剂中有高度的分散性, Pd的含量增加, 催化剂的催化效率提高, 且该催化剂对苯甲醇氧化具有较好的选择性和可重复使用性.     

Single‐Site AuI Catalyst for Silane Oxidation with Water

Single‐site Au anchored on mpg‐C₃N₄ (519 ppm Au loading) is developed as a highly active, selective, and stable catalyst for the oxidation of silanes with water with a turnover frequency as high as 50 200 h^?1, far exceeding most known catalysts based on total gold content. Other hydrosilanes bearing unsaturated functional groups also lead to corresponding silanols under mild reaction conditions without formation of any side products in good or excellent yields. The spherical aberration correction electron microscopy and extended X‐ray absorption fine structure measurements both confirm the atomic dispersion of Au atoms stabilized by mpg‐C₃N₄. The coordination of the catalytically active Au^I by three nitrogen or carbon atoms in the tri‐s‐triazine repeating units not only prevents the Au atoms from aggregation, but also renders the surface Au^I highly active, which is completely different than homogeneous Au^I species.     

Hydroxyl-Binding Energy-Induced Kinetic Gap Narrowing between Acidic and Alkaline Hydrogen Oxidation Reaction on Intermetallic Ru3Sn7 Catalyst

Developing highly efficient catalysts toward alkaline hydrogen oxidation reaction (HOR) and narrowing the kinetic gap between acidic and alkaline electrolytes are of great importance for the practical application of alkaline exchange membrane fuel cell . Herein, ordered Ru₃Sn₇/C intermetallic compound has been developed for the HOR under alkaline and acidic conditions. The authors demonstrate that the ordered intermetallic Ru₃Sn₇/C shows much enhanced HOR activity, stability, and CO-tolerance compared with its disordered RuSn solid solution alloy counterpart. More importantly, the authors find that the kinetic gap of HOR between acidic and alkaline media is significantly narrowed in the as-synthesized intermetallic Ru₃Sn₇/C catalysts. Combined experiment results and theoretical calculations, the authors understand that promoted hydroxyl-binding energy on Ru₃Sn₇/C derived from the intermetallic-induced strong electron interaction is responsible for the accelerated alkaline HOR performance and narrowed kinetic gap.     

用于亚硫酸根氧化速率测量的图像处理方法

开发了一种新的测量亚硫酸根氧化速率的图像处理方法。即在测量亚硫酸根氧化速率时 ,让单个氧气泡在亚硫酸钠溶液中反应 ,用摄像机拍下照片 ,用图像处理程序进行分析得出氧化速率。实验结果表明该方法具有很高的实用价值和精确性     

Engineered Cobalt Single-Atoms@BiFeO3 Heteronanostructures for Highly Efficient Solar Water Oxidation

Efficient charge–carrier separation and their utilization are the key factors in overcoming sluggish four-electron reaction kinetics involved in photocatalytic oxygen evolution. Here, a novel study demonstrates the significance of Na₂S₂O₈ as a sacrificial agent in comparison to AgNO₃. Resultantly, BiFeO₃ (BFO) and titanium doped-oxygen deficient BiFeO₃ (Ti-BFO-R) nanostructures achieve ≈64 and 44.5 times higher O₂ evolution in the presence of Na₂S₂O₈ compared to AgNO₃ as a sacrificial agent, respectively. Furthermore, the presence of Co single atoms (Co-SAs) deposited via immersion method on BFO and Ti-BFO-R nanostructures led to achieving outstanding O₂ evolution at a rate of 16.11 and 23.89 mmol g⁻¹ h⁻¹, respectively, which is 153 and 227.5 times higher compared to BFO (in the presence of AgNO₃), the highest O₂ evolution observed for BFO-based materials to date. The successful deposition of Co-SAs is confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM) and X-ray absorption near-edge structure (XANES). The charge transfer investigations confirm the significance of Co-SAs on BFO-based photocatalysts for improved charge–carrier separation, transport, and utilization. This novel study validates the excellent role of Na₂S₂O₈ as a sacrificial agent and Co-SAs as a cocatalyst for BFO-based nanostructures for efficient O₂ evolution.