Modulating CoFeOX Nanosheets Towards Enhanced CO2 Photoreduction to Syngas: Effect of Calcination Temperature and Mixed-Valence Multi-Metals

CoFeO_X nanosheets were synthesized by a facile coprecipitation and calcination method. The effect of calcination temperature on the crystal texture, morphology and surface areas of CoFeO_X were fully explored. CoFeO_X sample calcined at 600 °C (CoFeO_X-600) showed superior catalytic performance for the reduction of CO₂ under visible light. Compared with the pure Ru(bpy)₃²⁺-sensitized CO₂ reduction system, the CoFeO_X-added system achieved 19-fold enhancement of CO production (45.7 μmol/h). The mixed valence state and nanosheet-like structure of CoFeO_X cocatalyst support its ultra-high charge transfer and abundant CO₂ active adsorption sites exposure, which promote the separation of photogenerated charges, and thus improve the photocatalytic CO₂ reduction activity. Carbon source of CO from CO₂ was verified by ¹³CO₂ isotopic labelling experiment. Repeated activity experiments confirmed the good stability of CoFeO_X in the CO₂ photoreduction system. This work would provide prospective insights into developing novel cost-effective, efficient, and durable non-precious metal cocatalysts to improve the efficiency of photocatalytic reduction of CO₂.     

Ni-Fe/La2O2CO3催化乙醇水蒸气重整制氢的研究

采用La2(CO3)3空气焙烧法制备了La2O2CO3载体、采用浸渍法制备了Ni,Fe不同比例的Ni-Fe双金属催化剂及Ni/La2O2CO3,Fe/La2 O2 CO3催化剂,考察了各催化剂从300～700℃催化乙醇水蒸气重整反应的性能,并用BET,XRD,TPR等技术对催化剂进行表征。结果表明,相对单一金属催化剂,Ni-Fe双金属催化剂均表现出更高的活性,这可能是因为高分散的Ni,Fe和LaFeyNi1-yO3的共存作用。其中Ni含量为10%,Fe含量为5%时的Ni-Fe/La2O2CO3表现出最高的活性,400℃时乙醇的转化率为100%,H2的选择性最高达到94.1%,而CO的选择性则低至1.2%。     

Structure and Properties of Sol—Gel Derived CuNiMnZrO2 Catalysts for CO Hydrogenation

Two CuNiMnZrO2 catalysts (crystallized or non-crystallized) were prepared by co-hydrolyzing zirconium n-propoxide with Cu(NO3)2, Mn(NO3)2 and Ni(NO3)2 in an ethanol solution in the presence of diglycol. The physical and chemical properties of the catalysts were characterized using BET, XRD,TEM, XPS and CO-DRIFT techniques. It was found that the non-crystallizied CuNiMnZrO2 catalyst demonstrated highly dispersed active phases and high activity for CO adsorption, which resulted in good performance for synthesis of higher alcohols in CO hydrogenation compared to crystallized CuNiMnZrO2.     

A Triptycene-Based 2D MOF with Vertically Extended Structure for Improving the Electrocatalytic Performance of CO2 to Methane

Two-dimensional conductive metal-organic frameworks (2D-c-MOFs) have attracted extensive attention owing to their unique structures and physical-chemical properties. However, the planarly extended structure of 2D-c-MOFs usually limited the accessibility of the active sites. Herein, we designed a triptycene-based 2D vertically conductive MOF (2D-vc-MOF) by coordinating 2,3,6,7,14,15-hexahydroxyltriptycene (HHTC) with Cu²⁺. The vertically extended 2D-vc-MOF(Cu) possesses a weak interlayer interaction, which leads to a facile exfoliation to the nanosheet. Compared with the classical 2D-c-MOFs with planarly extended 2D structures, 2D-vc-MOF(Cu) exhibits a 100 % increased catalytic activity in terms of turnover number and a two-fold increased selectivity. Density functional theory (DFT) calculations further revealed that higher activity originated from the lower energy barriers of the vertically extended 2D structures during the CO₂ reduction reaction process.     

Ir/CeO2催化剂的表征和CO氧化性能

采用浸渍法制备了Ir/CeO2催化剂,考察了催化剂的CO氧化活性。随着Ir负载量的增加,Ir/CeO2催化剂的CO氧化活性先上升后下降,当Ir的负载量为1%时,催化剂的活性最高。Ir/CeO2催化剂中Ir以IrO2的形式存在,当低负载量(≤1%)时以高分散形式存在;高负载量(>1%)时以晶相IrO2的形式存在。随着Ir负载量增加,Ir粒子逐渐变大,反应比速率和反应转换频率(TOF)逐渐下降,表明小粒子上具有更高的CO反应活性。同时也发现金属态Ir催化剂的CO氧化活性高于氧化态IrOx催化剂。     

担载Fe2（CO）9络合物及其分散型Fe催化剂的CO吸脱附和催化作用

担载于Ａｌ２Ｏ３和ＺｒＯ２上的Ｆｅ（ＣＯ）９络合物的羰基在真空中极易脱附，在Ａｒ或Ｈ２中２５０℃左右也可完全脱羰而成分散型催化剂。以ＺｒＯ２为载体者在Ａｒ中低温下易发生表面岐化反应而生成ＣＯ２，高温下生成少量ＣＨ４。吸附于分散型催化剂上的ＣＯ在Ａｒ或Ｈ２中均易发生岐化反应，以ＺｒＯ２为载体者在Ｈ２中发生加氢反应而生成ＣＨ４，在ＣＯ加氢中其反应物除了大量ＣＯ２外还有少量ＣＨ物。原位ＦＴ－ＩＲ谱表明以     

Scalable,Durable, and Recyclable Metal-Free Catalysts for Highly Efficient Conversion of CO2 to Cyclic Carbonates

A series of highly active organoboron catalysts for the coupling of CO₂ and epoxides with the advantages of scalable preparation, thermostability, and recyclability is reported. The metal-free catalysts show high reactivity towards a wide scope of cyclic carbonates (14 examples) and can withstand a high temperature up to 150 °C. Compared with the current metal-free catalytic systems that use mol % catalyst loading, the catalytic capacity of the catalyst described herein can be enhanced by three orders of magnitude (epoxide/cat.=200 000/1, mole ratio) in the presence of a cocatalyst. This feature greatly narrows the gap between metal-free catalysts and state-of-the-art metallic systems. An intramolecular cooperative mechanism is proposed and certified on the basis of investigations on crystal structures, structure–performance relationships, kinetic studies, and key reaction intermediates.     

Cu Atomic Chain Supported on Graphene Nanoribbon for Effective Conversion of CO2 to Ethanol

Cu catalysts are well-known for their good performance in CO₂ conversion. Compared to CO and CH₄ production, C₂ products have higher volumetric energy densities and are more valuable in industrial applications. In this work, we screened the catalytic ability of C₂ production on several 1D Cu atomic chain structures and find that Cu edge-decorated zigzag graphene nanoribbons (Cu−ZGNR) are capable of catalyzing CO₂ conversion to ethanol, and CH₃CH₂OH is the main C₂ product with a maximum free energy change of 0.60 eV. The planar tetracoordinate carbon structures in Cu-ZGNR provide unique chemical bonding features for catalytic reaction on the Cu atoms. Detailed mechanism analyses with transition states search show that CO* dimerization is favored against CHO* formation in the reaction. By adjusting the CO* coverage, the selectivity of the C₂ product can be enhanced owing to less pronounced steric effects for COCHO*, which is feasible under experimental conditions. This study expands the catalyst family for C₂ products from CO₂ based on nano carbon structures with new features.     

CH4/CO2重整Ni基催化剂制备与催化性能的关系

用四种浸渍程序制备Ｎｉ－Ｍｇ／γ－Ａｌ２Ｏ３催化剂,其ＣＨ４／ＣＯ２重整制合成气的活性和积炭量的测试表明真空浸渍法最好,其次是二次不等量浸渍。现场ＣＯ歧化和ＣＨ４解离积炭实验表明,Ｎｉ基催化剂的积炭主要从反应生成物ＣＯ的歧化而来     

Strategies for Designing Nanoparticles for Electro‐ and Photocatalytic CO2 Reduction

Conversion of carbon dioxide (CO₂) into value‐added chemicals has attracted much attention because it can not only resolve global warming issues by reducing CO₂ accumulation in the atmosphere, but also produce renewable hydrocarbon fuels that are important feedstocks for the chemical industry. Among the diverse approaches reported, CO₂ reduction via electro‐ and photocatalytic methods is at the center of topics due to potential engineering of reaction performance through rational design of catalyst features. In this Minireview, we highlight recent strategies for designing nanoparticles to maximize the reaction efficiency and selectivity; from a materials viewpoint, these strategies can provide critical information to guide future research directions.     

CuO Catalysts Supported on Porous TiO2 Microspheres for Low-Temperature CO Oxidation

The porous TiO₂ microspheres were prepared by the reversed-phase suspension polymerization and sol-gel method using reversed-phase suspension droplets as the templates. The CO oxidation catalytic properties of the CuO/TiO₂ catalysts prepared by hydrothermal method and impregnation method were extensively investigated. The structure of CuO/TiO₂ catalysts was determined by TG-DTA, XRD, TEM, and XPS. The results indicated that the redox capacity of CuO/TiO₂ was greatly depended on the aqueous solution concentration of Cu(NO₃)₂ used in the preparation of CuO/TiO₂ and the calcination temperature of the CuO/TiO₂ catalysts.     

基于金属钴配合物的均相光催化还原二氧化碳研究进展

本文综述了自20世纪80年代以来基于钴配合物的均相光催化二氧化碳还原研究成果,以钴配合物催化剂的结构分类并结合时间顺序回顾了近四十年来该领域的发展轨迹,重点总结了用于光催化二氧化碳还原研究的金属钴配合物的结构、催化活性以及光催化体系的构成等特点,分析了该领域面临的挑战并展望了未来的发展方向。     

Rational Design of Carbon-Based 2D Nanostructures for Enhanced Photocatalytic CO2 Reduction: A Dimensionality Perspective

Photocatalytic CO₂ reduction is a revolutionary approach to solve imminent energy and environmental issues by replicating the ingenuity of nature. The past decade has witnessed an impetus in the rise of two-dimensional (2D) structure materials as advanced nanomaterials to boost photocatalytic activities. In particular, the use of 2D carbon-based materials is deemed as highly favorable, not only as a green material choice, but also due to their exceptional physicochemical and electrical properties. This Review article presents a diverse range of alterations and compositions derived from 2D carbon-based nanomaterials, mainly graphene and graphitic carbon nitride (g-C₃N₄), which have remarkably ameliorated the photocatalytic CO₂ performance. Herein, the rational design of the photocatalyst systems with consideration of the aspect of dimensionality and the resultant heterostructures at the interface are systematically analyzed to elucidate an insightful perspective on this pacey subject. Finally, a conclusion and outlook on the limitations and prospects of the cutting-edge research field are highlighted.     

Stability and Degradation Mechanisms of Copper‐Based Catalysts for Electrochemical CO2 Reduction

To date, copper is the only monometallic catalyst that can electrochemically reduce CO₂ into high value and energy‐dense products, such as hydrocarbons and alcohols. In recent years, great efforts have been directed towards understanding how its nanoscale structure affects activity and selectivity for the electrochemical CO₂ reduction reaction (CO₂RR). Furthermore, many attempts have been made to improve these two properties. Nevertheless, to advance towards applied systems, the stability of the catalysts during electrolysis is of great significance. This aspect, however, remains less investigated and discussed across the CO₂RR literature. In this Minireview, the recent progress on understanding the stability of copper‐based catalysts is summarized, along with the very few proposed degradation mechanisms. Finally, our perspective on the topic is given.     

Exfoliated 2D Layered and Nonlayered Metal Phosphorous Trichalcogenides Nanosheets as Promising Electrocatalysts for CO2 Reduction

Two-dimensional (2D) materials catalysts provide an atomic-scale view on a fascinating arena for understanding the mechanism of electrocatalytic carbon dioxide reduction (CO₂ ECR). Here, we successfully exfoliated both layered and nonlayered ultra-thin metal phosphorous trichalcogenides (MPCh₃) nanosheets via wet grinding exfoliation (WGE), and systematically investigated the mechanism of MPCh₃ as catalysts for CO₂ ECR. Unlike the layered CoPS₃ and NiPS₃ nanosheets, the active Sn atoms tend to be exposed on the surfaces of nonlayered SnPS₃ nanosheets. Correspondingly, the nonlayered SnPS₃ nanosheets exhibit clearly improved catalytic activity, showing formic acid selectivity up to 31.6 % with −7.51 mA cm⁻² at −0.65 V vs. RHE. The enhanced catalytic performance can be attributed to the formation of HCOO* via the first proton-electron pair addition on the SnPS₃ surface. These results provide a new avenue to understand the novel CO₂ ECR mechanism of Sn-based and MPCh₃-based catalysts.     

Design and Synthesis Strategies: 2D Materials for Electromagnetic Shielding/Absorbing

Two-dimensional (2D) materials possess special physical and chemical properties. They have been proved to have potential application advantage in the microwave absorption (MA) and electromagnetic interference (EMI) shielding. Particularly, they exhibit positive shielding and absorbing response to EMI. Here, the research progress of preparation, electromagnetic performance and microwave shielding/absorbing mechanisms of 2D composite materials are introduced. Effective preparation routes including introducing heteroatoms, constructing unique structures and 2D composite materials are described. Furthermore, the application prospects and challenges for the development of novel EMI materials are expatiated.     

助剂Mn对CO2加氢制二甲醚CuO-ZnO-ZrO2/HZSM-5催化剂的结构和性能影响

以无水乙醇为溶剂,草酸为沉淀剂,采用悬浮共沉淀法,一步合成Mn改性的CuO-ZnO-ZrO2/HZSM-5双功能催化剂.并研究了该催化剂在CO2加氢合成二甲醚反应中的催化性能,考察了助剂锰的添加量对催化剂性能的影响,并采用XRD、BET、TPR、NH3-TPD和XPS对催化剂结构进行表征.结果表明,双功能催化剂性能与助剂锰的添加量有密切联系,适量锰的加入可提供合适的表面酸性,提高二甲醚的选择性,降低副产物CO的选择性.表征结果表明,加入Mn可以促进CuO的分散,并降低CuO的还原温度,增加催化剂的比表面积,提高Cu+/Cu0比,从而能促进CO2的转化,有利于提高催化剂的活性.     

Effects of Carrier on CuO／TiO2 and CuO／Ti0.5Zr0.5O2 Catalysts in the NO＋CO Reaction

Using TiO2 and Ti0.5Zr0.5O2 as carriers, the CuO/TiO2 and CuO/Ti0.5Zr0.5O2 catalysts were prepared by the impregnation method with Cu(NO3)2 as active component. The catalytic activities in NO CO reaction were investigated using a microreactor-GC system, and structure and reducibility of catalysts were characterized by means of physical adsorption, TPR, XRD, NO-TPD technologies. It was found that the activity of CuO/Ti0.5Zr0.5O2 catalyst was higher than that of CuO/TiO2, probably due to the large specific surface area of Ti0.5Zr0.5O2 that played an important role in NO CO reaction.     

Achieving Simultaneous CO2 and H2S Conversion via a Coupled Solar‐Driven Electrochemical Approach on Non‐Precious‐Metal Catalysts

Carbon dioxide (CO₂) and hydrogen sulfide (H₂S) are generally concomitant with methane (CH₄) in natural gas and traditionally deemed useless or even harmful. Developing strategies that can simultaneously convert both CO₂ and H₂S into value‐added products is attractive; however it has not received enough attention. A solar‐driven electrochemical process is demonstrated using graphene‐encapsulated zinc oxide catalyst for CO₂ reduction and graphene catalyst for H₂S oxidation mediated by EDTA‐Fe²⁺/EDTA‐Fe³⁺ redox couples. The as‐prepared solar‐driven electrochemical system can realize the simultaneous conversion of CO₂ and H₂S into carbon monoxide and elemental sulfur at near neutral conditions with high stability and selectivity. This conceptually provides an alternative avenue for the purification of natural gas with added economic and environmental benefits.