纳米晶枝CuAu合金催化剂对二氧化碳电催化还原性能的研究（英文）

利用可再生清洁能源将CO_2转化为CO和其他小分子是合成含碳燃料的可观方法之一。间歇性可再生能源存储的重要策略之一是将二氧化碳进行电化学还原。选择具有高活性和稳定性的电催化剂对于电化学还原CO_2至关重要。在这项研究中,我们使用简单的电沉积方法合成了具有纳米晶枝状结构的CuAu合金电极。各项表征显示原子比约为1:1的CuAu纳米枝晶对CO_2的电化学还原具有出色的催化活性。合成的主要产物是H2和CO,这是合成气体是合成天然气,氨和甲醇合成的中间体。电化学阻抗谱(EIS)测量表明,相对于Cu和Au电沉积催化剂,CuAu纳米晶枝状催化剂具有相对低的电荷转移阻力。CuAu纳米枝晶催化剂是一种具有潜在的转化CO_2为合成气体的高活性电催化剂。     

纳米Pd和Au催化CO2还原粒径效应的密度泛函理论计算研究

以可再生能源为能量来源,在水溶液中进行的光(电)催化CO2还原生成高附加值化学品和燃料是解决能源危机与环境污染的有效途径之一.CO是一种简单却很重要的CO2还原产物,它可以作为水煤气变换反应与费托合成的重要原料.具有较高CO选择性的贵金属纳米颗粒催化剂(如Au和Pd)一直受到研究者的广泛关注.一般来说,金属颗粒催化剂的...     

电催化动力学简介（英文）

电催化过程是实现社会向可再生能源与化学品转型的主要驱动力之一。电催化动力学分析是探索反应机理和建立电催化剂构效关系行之有效的方法。本文将通过三个广泛研究的电催化反应：电化学CO₂、CO还原反应和氧还原反应,探讨Tafel分析的普遍过程、隐含假设以及需要注意的问题。此外,本文将介绍电化学反应活化参数的基本概念和关键热力学、动力学变量之间的关系。     

Au24和Au25纳米团簇对二氧化碳电化学还原反应催化活性的分析

通过电化学催化过程将二氧化碳(CO2)还原为有用的燃料和化学品是目前降低CO2排放量以及高效利用CO2的主要方式之一.金纳米团簇(Au NCs)因其结构明确、原子级尺寸精确和高表面活性而被认为是CO2电化学还原反应(CO2RR)的良好催化材料和模型催化剂.本研究可控合成了两种金纳米团簇Au24 NCs和Au25 NCs...     

二氧化碳电化学还原的研究进展

利用低品阶的可再生电能,将二氧化碳(CO_2)电化学还原生成高附加值的化学品或燃料,既可以"变废为宝"、减少CO_2排放,又能将可再生能源转变为高能量密度的燃料储存,具有重要的现实意义。电化学还原CO_2的研究,是目前世界范围内的研究热点,许多标志性的重要研究成果不断涌现。本文首先简要介绍了CO_2电化学还原的基本原理,然后概述了近5年来在其电催化剂材料和反应机理相关的实验与理论研究方面的昀新研究进展,昀后对其发展趋势进行了展望。     

红外光谱电化学研究金电极表面上CO2的还原

以碳酸丙烯酯(PrC)为溶剂,高氯酸四丁基胺(TBAP)为电解质,利用电化学及红外光谱电化学开展了金电极上二氧化碳的还原研究。运用现场红外光谱跟踪电化学还原过程反应物及产物的生成和消失。红外光谱电化学循环伏吸法表明,在消耗CO2的同时,金电极上有CO的产生,且伴随有碳酸根的形成。结合电化学和光谱电化学结果,提出了一种电还原机理:在非水介质中,CO2电还原过程中生成了中间体CO2.-,随后CO2.-分别以两个途径进行还原,其一是直接被还原成CO,其二是与CO2结合生成C2O4.-而后歧化成CO以及CO32-。两个反应同时进行,且第一个反应是可逆过程。     

太阳能驱动Ni-N掺杂多孔碳高效电催化还原CO2为CO

利用可再生能源将二氧化碳(CO2)电催化还原为有价值的化学品和燃料,不仅可缓解温室效应,而且可实现碳资源的循环利用。以蛋白胨与盐形成的凝胶为原料,经高温热解后制备了用于电还原CO2的Ni-N掺杂碳多孔催化剂。该催化剂表现出优异的电催化还原CO2为CO的性能,在电压为-0.66 V(vs.RHE)下,CO的法拉第效率为92.0%,过电位为550 mV,还原电流密度为2.5 mA·cm-2。该催化剂优异的CO2的电催化活性归因于其存在的Ni-N活性位点和高度多孔的结构。此外,利用太阳能电池产生的电能,该催化剂可持续进行CO2电催化还原为CO,为CO2的资源化利用提供了有价值的参考。     

基于理论指导的电催化剂调控:从机制分析到结构设计（英文）

电催化在许多清洁能源转换技术中起着核心作用,能够与光伏、风电和水电等可再生能源发电系统耦合,解决全球能源和气候危机.一些重要的电化学转化过程,包含析氢反应(HER)、析氧反应(OER)、氧还原反应(ORR)、氮还原反应(NRR)和二氧化碳还原(CO2RR)等,引起了广泛的研究兴趣.实现这些电催化技术大规模应用的核心在于开发先进的电催化材料.传统电催化剂的研发依赖于“试错法”实验合成,这一过程耗时漫长、成本较高.近20年来,基于理论指导的新材料开发成为更先进的电催化剂设计思路,这主要受益于:(1)重要的基本理论、活性描述符与催化剂机制的确立;(2)计算化学在电化学领域的成熟.这些进展揭示了电催化剂的构效规律,加速了电催化剂的研发过程.本文梳理了电催化剂设计理论发展的关键历程.首先,萨巴捷原则指出理想催化剂的吸附应该是“中庸”的:过弱的吸附无法使反应发生,过强的吸附将导致催化剂表面被覆盖而无法进一步反应.火山型曲线准确描绘了这一现象,并为此提供了可定量的数学表达,但仍缺少量化吸附的物理量.随着计算机技术与密度泛函理论的不断发展,人们能够获得吸附能、活化能等微观物理量.同时, Br?nste...     

金属纳米材料的相工程助力高效二氧化碳电还原

<正>电化学还原二氧化碳(CO₂)可将温室气体转化为高附加值的碳基燃料和化学品,为解决能源与环境危机提供了一种可持续途径^1–3。金属纳米材料是电还原CO₂的一类高效催化剂,具有广阔的应用前景。例如,金(Au)基纳米材料是常用的制备一氧化碳(CO)产物的电催化剂~4,而铜(Cu)基纳米材料则可以将CO₂转化为多种碳氢产物~5。     

铋基二氧化碳还原电催化材料研究进展

二氧化碳（CO₂）作为一种经济、安全、可再生的碳资源化合物,其高效回收利用一直是全社会关注的焦点. 利用电化学方法,将CO₂还原转化生成一系列高附加值的化学品或燃料,对于缓解能源与环境双重压力具有重要的现实意义. 本论文介绍了电化学CO₂还原反应的基本原理与过程,综述了近年来铋基催化材料的发展现状,重点对这类催化材料的制备合成、结构调控、催化反应机理研究等方面进行了总结,最后对其未来发展方向进行了探讨与展望.     

Atomic Layer Deposition of ZnO on CuO Enables Selective and Efficient Electroreduction of Carbon Dioxide to Liquid Fuels

Electrochemical reduction of carbon dioxide, if powered by renewable electricity, could serve as a sustainable technology for carbon recycling and energy storage. Among all the products, ethanol is an attractive liquid fuel. However, the maximum faradaic efficiency of ethanol is only ≈10 % on polycrystalline Cu. Here, CuZn bimetallic catalysts were synthesized by in situ electrochemical reduction of ZnO‐shell/CuO‐core bi‐metal‐oxide. Dynamic evolution of catalyst was revealed by STEM‐EDS mapping, showing the migration of Zn atom and blending between Cu and Zn. CuZn bimetallic catalysts showed preference towards ethanol formation, with the ratio of ethanol/ethylene increasing over five times regardless of applied potential. We achieved 41 % faradaic efficiency for C₂₊ liquids with this catalyst. Transitioning from H‐cell to an electrochemical flow cell, we achieved 48.6 % faradaic efficiency and ?97 mA cm^?2 partial current density for C₂₊ liquids at only ?0.68 V versus reversible hydrogen electrode in 1 m KOH. Operando Raman spectroscopy showed that CO binding on Cu sites was modified by Zn. Free CO and adsorbed *CH₃ are believed to combine and form *COCH₃ intermediate, which is exclusively reduced to ethanol.     

Intermetallic CuAu nanoalloy for stable electrochemical CO2 reduction

Copper is one of the most efficient catalysts widely investigated in electrochemical CO₂ reduction, however, the further development of copper-based catalysts is constrained by severe stability problems. In this work, we developed a method for the synthesis of highly ordered CuAu intermetallic nanoalloys (o-CuAu) under mild conditions (< 250 °C), which can convert carbon dioxide to carbon monoxide with high selectivity and can operate stably for 160 h without current decay. The improved stability is believed to be due to the increased mixing enthalpy and stronger atomic interactions between Cu and Au atoms in the intermetallic nanoalloy. In addition, XPS results, Tafel slope and in situ IR spectroscopy demonstrate that high valence gold atoms on o-CuAu surface promote the reduction of CO₂. In contrast, the disordered CuAu nanoalloy (d-CuAu) underwent atomic rearrangement to form a Cu-rich structure on the surface, leading to reduced stability. These findings may provide insight into the rational design of stable CO₂RR electrocatalysts through proper structural engineering.     

Bipyridine‐Assisted Assembly of Au Nanoparticles on Cu Nanowires To Enhance the Electrochemical Reduction of CO2

We report a new strategy to prepare a composite catalyst for highly efficient electrochemical CO₂ reduction reaction (CO₂RR). The composite catalyst is made by anchoring Au nanoparticles on Cu nanowires via 4,4′‐bipyridine (bipy). The Au‐bipy‐Cu composite catalyzes the CO₂RR in 0.1 m KHCO₃ with a total Faradaic efficiency (FE) reaching 90.6 % at ?0.9 V to provide C‐products, among which CH₃CHO (25 % FE) dominates the liquid product (HCOO^?, CH₃CHO, and CH₃COO^?) distribution (75 %). The enhanced CO₂RR catalysis demonstrated by Au‐bipy‐Cu originates from its synergistic Au (CO₂ to CO) and Cu (CO to C‐products) catalysis which is further promoted by bipy. The Au‐bipy‐Cu composite represents a new catalyst system for effective CO₂RR conversion to C‐products.     

铜基串联催化剂电催化CO2还原的研究进展

Through the combustion of fossil fuels and other human activities, large amounts of CO₂ gas have been emitted into the atmosphere, causing many environmental problems, such as the greenhouse effect and global warming. Thus, developing and utilizing renewable clean energy is crucial to reduce CO₂ emission and achieve carbon neutrality. The electrochemical CO₂ reduction reaction (CO₂RR) has been considered as an effective approach to obtain high value-added chemicals and fuels, which can store intermittent renewable energy and achieve the artificial carbon cycle. In addition, due to its multiple advantages, such as mild reaction conditions, tunable products, and simple implementation, electrochemical CO₂RR has attracted extensive attention. Electrochemical CO₂RR involves multiple electron–proton transfer steps to obtain multitudinous products, such as C₁ products (CO, HCOOH, CH₄, etc.) and C₂ products (C₂H₄, C₂H₅OH, etc.). The intermediates, among which ^*CO is usually identified as the key intermediate, and reaction pathways of different products intersect, resulting in an extremely complex reaction mechanism. Currently, copper has been widely proven to be the only metal catalyst that can efficiently reduce CO₂ to hydrocarbons and oxygenates due to its suitable adsorption energy for ^*CO. However, the low product selectivity, poor stability, and high overpotential of pure Cu hinder its use for the production of industrial-grade multi-carbon products. Tandem catalysts with multiple types of active sites can sequentially reduce CO₂ molecules into desired products. When loaded onto a co-catalyst that can efficiently convert CO₂ to ^*CO (such as Au and Ag), Cu acts as an electron donor owing to its high electrochemical potential. ^*CO species generated from the substrate can spillover onto the surface of electron-poor Cu due to the stronger adsorption and be further reduced to C₂₊ products. The use of Cu-based tandem catalysts for electrochemical CO₂RR is a promising strategy for improving the performance of CO₂RR and thus, has become a research hotspot in recent years. In this review, we first introduce the reaction routes and tandem mechanisms of electrochemical CO₂RR. Then, we systematically summarize the recent research progress of Cu-based tandem catalysts for electrochemical CO₂RR, including Cu-based metallic materials (alloys, heterojunction, and core-shell structures) as well as Cu-based framework materials, carbon materials, and polymer-modified materials. Importantly, the preparation methods of various Cu-based tandem catalysts and their structure–activity relationship in CO₂RR are discussed and analyzed in detail. Finally, the challenges and opportunities of the rational design and controllable synthesis of advanced tandem catalysts for electrochemical CO₂RR are proposed.     

反应条件对铜催化CO2电还原的影响

工业规模的化石能源消耗导致大气中二氧化碳含量不断增加,CO₂转化利用成为人们日益关注的热点问题. 金属铜因其成本低廉、储量丰富,并且具有独特的CO₂亲和力能够生成多碳化合物,是目前CO₂电还原中研究最为广泛深入的电极材料. 由于阴、阳离子的特征吸附对Cu电极性能有显著影响,并且不同反应体系中对Cu电极上CO₂吸附、活化影响也有所不同,因此导致金属Cu电极上报道的电催化活性、产物种类与选择性等都非常宽泛. 基于此,有必要系统地研究各种反应条件对金属Cu电极电催化CO₂还原性能的影响. 作者选择了平均粒径为600 nm的商品化金属Cu颗粒作为电还原CO₂的催化剂,研究了不同反应条件包括各种常用电解质溶液、KHCO₃的浓度以及H型电解池和流动池. 实验结果表明,浓度为0.5 mol·L ^-1的KHCO₃作为电解质溶液具有较好催化活性和较高的产物分电流密度,流动池可以进一步提高主要产物甲酸盐和CO的分电流密度. 本研究工作从反应条件的角度对CO₂还原的电催化转化进行了系统研究,有助于理解电解液和反应器等因素对CO₂电还原反应过程的影响规律.     

钯基纳米材料电化学还原二氧化碳研究进展

电化学二氧化碳还原是利用电能驱动将CO_2高效转化为小分子碳基燃料的新方法,被认为是目前最具应用潜力的碳资源转化技术之一。然而,CO_2还原反应仍面临着诸多挑战,如反应过电位高,产物选择性低以及析氢反应的竞争等。因此,开发高效的电催化剂是发展CO_2还原技术的核心关键。近年来,Pd基材料在CO_2还原反应中表现出独特的催化性能优势:它不仅可以在接近平衡电位下高选择性地还原CO_2生成甲酸/甲酸盐,还能够在一定的负电位区间高效地还原CO_2生成CO。尽管如此,Pd基材料目前仍存在着成本较高、活性不理想以及稳定性差等问题,严重制约了其进一步应用与发展。对此,本文首先简单介绍了CO_2RR的基本原理,并综述了近年来Pd基催化剂电还原CO_2的应用研究及发展现状。重点探讨了尺寸效应、形貌效应、合金效应、核壳效应及载体效应等对Pd基催化剂性能的影响。最后针对这类材料的问题挑战及其未来发展方向进行了探讨与展望。     

铜基串联催化剂电催化CO2还原的研究进展

化石燃料的燃烧和其他人类活动排放了大量的CO₂气体,引发了诸多环境问题。电催化CO₂还原反应(CO₂RR)可以储存间歇可再生能源,实现人为闭合碳循环,被认为是获得高附加值化学品和燃料的有效途径。电催化CO₂RR涉及多个电子-质子转移步骤,其中^*CO通常被认为是关键中间体。铜由于对^*CO具有合适的吸附能,已被广泛证明是唯一能够有效地将CO₂还原为碳氢化合物和含氧化合物的金属催化剂。然而,纯Cu稳定性差、产品选择性低、过电位高,阻碍了工业级多碳产品的生产。构筑Cu基串联催化剂是提高CO₂RR性能的一种有前途的策略。本文首先介绍电催化CO₂RR的反应路线和串联机理。然后,系统地总结铜基串联催化剂对电催化CO₂RR的最新研究进展。最后,提出合理设计和可控合成新型电催化CO₂RR串联催化剂面临的挑战和机遇。     

Effect of surface structure on the catalytic behavior of Ni：Cu/Al and Ni：Cu：K/Al catalysts for methane decomposition

Methane decomposition using nickel, copper, and aluminum （Ni：Cu/Al） and nickel, copper, potassium, and aluminum （Ni：Cu：K/Al） modified nano catalysts has been investigated for carbon fibers, hydrogen and hydrocarbon production. X-ray photoelectron spectroscopy （XPS）, static secondary ion mass spectrometry （SSIMS）, thermal gravimetric analysis （TGA）, Fourier transform infrared （FT-IR）, secondary electron microscopy/X-ray energy dispersive （SEM-EDX）, and temperature programmed desorption （TPD） were used to depict the chemistry of the catalytic results. These techniques revealed the changes in surface morphology and structure of Ni, Cu, Al, and K, and formation of bimetallic and trimetallic surface cationic sites with different cationic species, which resulted in the production of graphitic form of pure carbon on Ni：Cu/Al catalyst. The addition of K has a marked effect on the product selectivity and reactivity of the catalyst system. K addition restricts the formation of carbon on the surface and increases the production of hydrogen and C2, C3 hydrocarbons during the catalytic reaction whereas no hydrocarbons are produced on the sample without K. This study completely maps the modified surface structure and its relationship with the catalytic behavior of both systems. The process provides a flexible route for the production of carbon fibers and hydrogen on Ni：Cu/Al catalyst and hydrogen along with hydrocarbons on Ni：Cu：K/Al catalyst. The produced carbon fibers are imaged using a transmission electron microscope （TEM） for diameter size and wall structure determination. Hydrogen produced is COx free, which can be used directly in the fuel cell system. The effect of the addition of Cu and its transformation and interaction with Ni and K is responsible for the production of CO/CO2 free hydrogen, thus producing an environmental friendly clean energy.     

水相介质中负载纳米金催化CO高选择性还原糠醛

近年来可再生资源以及化工原料的多元化备受关注,生物资源成为其中的一个新亮点。糠醛是一种可由生物质转化而来的重要化工原料,将其催化还原直接转化为糠醇是构建以糠醛为平台化合物的生物基呋喃衍生物价值链的重要环节。长久以来,糠醛制糠醇研究主要集中在以 H2作氢源的加氢工艺及相关催化剂配方的优化、改进等方面,尽管在工业上已获得成功应用,但由于需大量消耗源于化石燃料的 H2,使得该路线总体上仍依赖于化石能源。此外,大量使用 H2所涉及的储存、运输和使用条件苛刻以及如何有效控制目标产物的选择性等问题也一直是糠醛传统催化加氢所面临的挑战。因此,寻求可替代传统氢气作氢源,更为经济实用且高效的糠醛高选择性催化还原制糠醇路线,对于发展以糠醛转化为技术核心的新一代糠醛基化工产业链,以及实现诸如5-羟甲基糠醛等其它重要生物质基平台化合物的还原转化,均具有重要意义。本文旨在通过实证性实验,考察以价廉且来源丰富的 CO替代 H2来实现高选择性液相糠醛催化转化制糠醇的可行性。众所周知, CO不但是 C1化学工业中至关重要的基础原料,在发展并完善面向未来的低碳能源及化学品清洁合成新技术等方面也有着非常大的应用潜力。鉴于 CO也是炼钢焦炉气的重要组成部分,因此开发新颖的基于 CO的还原转化和相关反应新技术,不但可有效拓展 CO的潜在应用范围,对于实现传统高能耗行业的节能减排和转型升级也有着重要的启示和借鉴意义。我们近期利用 CO/H2O为还原介质,在温和条件下实现了纳米 Au催化取代硝基或羰基化合物高效、高化学选择性还原,本文系统研究了包括传统铂族金属在内的各类高分散贵金属催化剂、反应温度、反应压力以及反应时间等对糠醛转化率和糠醇选择性的影响。通过优化催化剂制备和反应条件,发现以 CO/H2O作为氢源,在金红石单相 TiO2负载纳米 Au(Au/TiO2-R)的催化作用下,于90oC, CO压力为4 MPa,糠醛与 Au的摩尔比为200的条件下反应4 h即可实现糠醛至
　　糠醇的定量转化。研究表明,上述过程中催化剂可多次循环使用;反应温度或反应压力的增加均有利于反应进行,且在糠醛与纳米 Au的摩尔比高达2000甚至5000时,反应仍可完全进行到底。尤其值得一提的是,该催化体系对于反应原料中含有相当杂质的非新鲜提纯的粗糠醛亦具有很好的耐受性,甚至可直接以各种 H2/CO比例的来源广泛的合成气为氢源,实现目标反应,表明该体系是一种极具开发和应用潜力的糠醛转化制糠醇新技术。     

Experimental and computational investigation of Au25 clusters and CO2: a unique interaction and enhanced electrocatalytic activity

Atomically precise, inherently charged Au(25) clusters are an exciting prospect for promoting catalytically challenging reactions, and we have studied the interaction between CO(2) and Au(25). Experimental results indicate a reversible Au(25)-CO(2) interaction that produced spectroscopic and electrochemical changes similar to those seen with cluster oxidation. Density functional theory (DFT) modeling indicates these changes stem from a CO(2)-induced redistribution of charge within the cluster. Identification of this spontaneous coupling led to the application of Au(25) as a catalyst for the electrochemical reduction of CO(2) in aqueous media. Au(25) promoted the CO(2) → CO reaction within 90 mV of the formal potential (thermodynamic limit), representing an approximate 200-300 mV improvement over larger Au nanoparticles and bulk Au. Peak CO(2) conversion occurred at -1 V (vs RHE) with approximately 100% efficiency and a rate 7-700 times higher than that for larger Au catalysts and 10-100 times higher than those for current state-of-the-art processes.