Mechanistic aspects of facet-dependent CH4/C2+ selectivity over a χ-Fe5C2 Fischer-Tropsch catalyst

Structure-performance relationship is a complex issue in iron-catalyzed Fischer-Tropsch synthesis,and it is not easy to elucidate it by experimental investigations.First-principle calculation is a powerful method for explaining experimental results and guiding catalyst design.In this study,we investigated the reaction mechanisms of CH₄formation and C-C coupling on fourχ-Fe₅C₂ surfaces and established the kinetic equations to compare the rates of CH₄ fo...     

Selective capture of Tl2O from flue gas with formation of p–n junction on V2O5–WO3/TiO2 catalyst under working conditions

Thallium(Tl) compounds, highly toxic to biology, are usually released into flue gas during fossil/minerals combustion, and further distributed in water and soil. In this work, we fundamentally investigated the capture of gaseous Tl₂O by industrial V₂O₅–WO₃/TiO₂ catalyst under working condition in Tl-containing flue gas. Experimental and theoretical results indicated that the Tl₂O has significant electron-feeding capacity and easil...     

Auδ--Ov-Ti3+: Active site of MOx-Au/TiO2 catalysts for the aerobic oxidation of 5-hydroxymethylfurfural

Despite wide applications of noble metal-based catalysts in 5-hydroxymethylfurfural(HMF) oxidation,promoting the catalytic performance at low loading amounts still remains a significant challenge.Herein,a series of metal oxide modified MO_x-Au/TiO₂(M=Fe,Co,Ni) catalysts with low Au loading amount of 0.5 wt% were synthesized.Addition of transition metal oxides promotes electron transfer and generation of the Au^δ--O_v-Ti³⁺ interface.A combinatio...     

Mechanochemical synthesis of oxygenated alkynyl carbon materials with excellent Hg(Ⅱ) adsorption performance from CaC2 and carbonates

Adsorptive removal of heavy metal ions from wastewater is very important, and the key is the development of efficient sorbents. In this work,oxygenated alkynyl carbon materials(OACMs) were synthesized via mechanochemical reaction of CaC₂ and a carbonate(CaCO₃, Na₂CO₃, or NaHCO₃) at ambient temperature. The resultant OACMs are micro mesoporous carbon nanomaterials with high specific area(>648 m²g^-1),highly crosslinked...     

Techno-economic assessment of a chemical looping splitting system for H2 and CO Co-generation

The natural gas(NG) reforming is currently one of the low-cost methods for hydrogen production. However, the mixture of H₂ and CO₂ in the produced gas inevitably includes CO₂ and necessitates the costly CO₂ separation. In this work, a novel double chemical looping involving both combustion(CLC) and sorption-enhanced reforming(SE-CLR) was proposed towards the co-production of H₂ and CO(CLC-SECLRHC) in two separated streams. CLC provides react...     

Oxygen vacancy defects engineering on Cu-doped Co3O4 for promoting effective COS hydrolysis

The activation of H₂O is a key step of the COS hydrolysis,which may be tuned by oxygen vacancy defects in the catalysts.Herein,we have introduced Cu into Co₃O₄ to regulate the oxygen vacancy defect content of the catalysts.In situ DRIFTS and XPS spectra reveal that COS and H₂O are adsorbed and activated by oxygen vacancy.The 10 at% Cu doped Co₃O₄ sample(10Cu-Co₃O₄) exhibits the optimal activity,100% of COS co...     

CO2 capture and conversion to value-added products promoted by MXene-based materials

Carbon dioxide(CO₂ ) capture and conversion is the key route for the mitigation of the greenhouse effect and utilization of carbon sources to obtain value-added products or fuels. Much attention is paid to the development of novel materials with high CO₂ adsorption capacity and conversion rate. MXene is the graphene-like two-dimensional metal carbide/nitride/carbonitride owning favorable structure, morphology, high surface-bulk ratio, and physicochemical properties. Here, w...     

3D flower-like mesoporous Bi4O5I2/MoS2 Z-scheme heterojunction with optimized photothermal-photocatalytic performance

3D flower-like hierarchical mesoporous Bi₄O₅I₂/MoS₂ Z-scheme layered heterojunction photocatalyst was fabricated by oil bath and hydrothermal methods. The heterojunction with narrow band gap of ～1.95 eV extended the photoresponse to near-infrared region, which showed obvious photothermal effect due to the introduction of MoS₂ with broad spectrum response. MoS₂ nanosheets were anchored onto the surface of flower-like hierarchical m...     

Intercalation assisted liquid phase production of disulfide zirconium nanosheets for efficient electrocatalytic dinitrogen reduction to ammonia

Disulfide zirconium(ZrS₂) is a two-dimensional(2D) transition metal disulfide and has given rise to extensive attention because of its distinctive electronic structure and properties.However,mass production of high quality of ZrS₂ nanosheets to realize their practical application remains a challenge.Here,we have successfully exfoliated the bulk ZrS₂ powder with the thickness of micron into single and few-layer nanosheets through liquid-phase exfoliation in N-meth...     

机械混合法制备TiO2/g-C3N4复合材料及其光催化降解双酚A的性能

本工作采用机械混合方法,将TiO₂纳米颗粒与不同质量的g-C₃N₄复合,制备了一系列具有不同g-C₃N₄含量的TiO₂/g-C₃N₄复合材料.运用X射线粉末衍射（XRD）、X射线光电子能谱（XPS）、拉曼光谱（Raman）、比表面积分析仪（BET）、扫描电镜（SEM）和透射电镜（TEM）对材料的化学组成和形貌特征进行了表征.比较了g-C₃N₄、TiO₂和一系列TiO₂/g-C₃N₄在可见光驱动下对水中双酚A（BPA）的降解效率和矿化能力差异,发现TiO₂/g-C₃N₄的光催化活性显著高于g-C₃N₄和TiO₂,其中以TiO₂/g-C...     

Metal organic framework supported niobium pentoxide nanoparticles with exceptional catalytic effect on hydrogen storage behavior of MgH2

Nb₂O₅ nanoparticles with an average particle size of 10 nm supported on a rhombic dodecahedral metal organic framework(MOF) were successfully synthesized by a facile one-pot hydrothermal reaction and subsequent calcination process.Experimental results demonstrated that the prepared catalyst drastically improved the hydrogen storage behavior of MgH₂.7 wt% Nb₂O₅@MOF doped MgH₂ started to desorb hydrogen at 181.9℃ and 6.2 wt% hydroge...     

Fe3O4/MoS2强化过氧化单硫酸盐活化去除2,4-二氯苯氧乙酸

以MoS₂为载体,通过水热法合成Fe₃O₄/MoS₂催化剂,采用X射线衍射、透射电子显微镜和X射线光电子能谱分析对材料进行表征,研究了Fe₃O₄/MoS₂/PMS体系中2,4-二氯苯氧基乙酸（2,4-D）的降解效率并探究了其反应机理.结果表明,以Fe₃O₄、MoS₂和Fe₃O₄/MoS₂为催化剂,30 min内2,4-D的去除率分别为31%、 20%和89%.表征结果发现,在MoS₂的存在下,Fe₃O₄表面的Fe（Ⅲ）还原为Fe（Ⅱ）,Mo（Ⅳ）被氧化为Mo（Ⅵ）,Fe₃O₄和MoS₂间的协同作用加强了PMS分解,提高了2,4-D去除效率.自由基淬灭实验表明,·OH、 SO<...     

Mechanism of CO2 reduction in carbonylation reaction promoted by ionic liquid additives: A computational and experimental study

The Ru-catalyzed carbonylation of alkenes with CO₂ as a C1 surrogate and imidazole chlorides as the promotor is investigated by a combination of computational and experimental study. The conversion rate of CO₂ to CO is positively correlated with the efficiency of both hydroesterification and hydroformylation, which is found facilitated in the presence of chloride additives with a decreasing order of BmimCl ～ B3MimCl > BmmimCl ～ LiCl. Taking the hydroesterification with M...     

Plasma treated M1 MoVNbTeOx-CeO2 composite catalyst for improved performance of oxidative dehydrogenation of ethane

High activity and productivity of MoVNbTeO_x catalyst are challenging tasks in oxidative dehydrogenation of ethane(ODHE) for industrial application.In this work,phase-pure M1 with 30 wt% CeO₂ composite catalyst was treated by oxygen plasma to further enhance catalyst performance.The results show that the oxygen vacancies generated by the solid-state redox reaction between Ml and CeO₂ capture active oxygen species in gas and transform V⁴⁺ to V⁵⁺     

The newly-assisted catalytic mechanism of surface hydroxyl species performed as the promoter in syngas-to-C2 species on the Cu-based bimetallic catalysts

In the conversion process of syngas-to-C₂ species,the OH species are inevitably produced accompanying the production of key intermediates CH_x(x=1-3),traditionally,the function of surface OH species is generally accepted as the hydrogenating reactive species.This work for the first time proposed and confirmed the assisted catalytic mechanism of surface OH species that performed as the promoter for syngas-to-C₂species on Cu-based catalysts.DFT and microkinetic mode...     

A highly dispersed Pt/copper modified-MnO2 catalyst for the complete oxidation of volatile organic compounds: The effect of oxygen species on the catalytic mechanism

Manganese oxide(MnO₂) exhibits excellent activity for volatile organic compound oxidation.However,it is currently unknown whether lattice oxygen or adsorbed oxygen is more conducive to the progress of the catalytic reaction.In this study,novel hollow highly dispersed Pt/Copper modified-MnO₂ catalysts were fabricated.Cu²⁺ was stabilized into the δ-MnO₂ cladding substituting original K⁺,which produced lattice defects and enhance the content of...     

Heterostructuring noble-metal-free 1T' phase MoS2 with g-C3N4 hollow nanocages to improve the photocatalytic H2 evolution activity

In this work,we report the preparation of 1T’-MoS₂/g-C₃N₄ nanocage(NC) heterostructure by loading 2D semi-metal noble-metal-free 1T’-MoS₂ on the g-C₃N₄ nanocages(NCs).DFT calculation and experimental data have shown that the 1T’-MoS₂/g-C₃N₄ NC heterostructure has a stronger light absorption capacity and larger specific surface area than pure g-C₃N₄ NCs and g-C₃N     

Direct production of hydrogen peroxide over bimetallic CoPd catalysts:Investigation of the effect of Co addition and calcination temperature

A series of CoPd/KIT-6 bimetallic catalysts with various Co:Pd molar ratios at different calcination temperatures were prepared and used for the direct synthesis of H₂O₂ from H₂ and O₂. These catalysts were characterized by nitrogen adsorption–desorption, low and wide-angle X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), transmission electron microscopy(TEM), scanning electron microscopy(SEM),elemental mapping and energy-dispersive X-ray...     

Vacancy engineering of oxidized Nb2CTx MXenes for a biased nitrogen fixation

The artificial nitrogen(N₂) reduction reaction(NRR) via electrocatalysis is a newly developed methodology to produce ammonia(NH₃) at ambient conditions,but faces the challenges in N₂ activation and poor reaction selectivity.Herein,Nb-based MXenes are developed to remarkably enhance the NRR activity through the engineering of the stretched 3D structure and oxygen vacancies(V_O).The theoretical studies indicate that N₂ could be initially adsorb...     

Synergistic effect of Ni~Ⅱ and Co/Fe~Ⅲ in doped mixed-valence phosphonate for enhancing electrocatalytic oxygen evolution

Metal organophosphonates have been explored in energy-related fields due to their high chemical and thermal stability as a type of uniformly precursor,but only few of pristine metal organophosphonate are directly used for oxygen evolution reaction (OER) catalysts.Here,a mixedvalence iron phosphonate (Fe₃-ppat) has been constructed and applied to OER catalysis considered the potential active sites in pillars Fe~Ⅱ(-H₂O)₄(COO)₂ and inorganic layers Fe~Ⅲ(μ...