【作者】 王涛；

【导师】 程淑艳；

【作者基本信息】 山西大学 ， 环境工程， 2025， 硕士

【摘要】 随着全球工业化进程加速,二氧化碳过量排放引发的温室效应已成为威胁人类可持续发展的重大环境问题。电催化二氧化碳还原（ECR）技术能够将CO₂转化为高附加值化学品(如CO、甲酸、C₂₊烃类等产物),通过耦合可再生能源可以加速“碳循环”,是助力“碳中和”目标实现的关键途径之一。类水滑石材料因其具有金属阳离子种类和比例可调、比表面积大、CO₂吸附能力强、有更多的反应活性位点和丰富的路易斯碱位点等优势而备受关注,但其ECR效率和产物选择性仍需进一步提升。本文以铜基类水滑石（LDH）衍生氧化物为研究对象,通过硫元素掺杂与形貌调控策略,系统探究催化剂ECR性能的优化机制,为设计高效的ECR催化剂提供实验指导和理论依据。通过共沉淀法合成CuZnAl-LDH前驱体,并引入小分子有机化合物异硫氰酸甲酯作为硫源,焙烧后得到了CuZnAlO_xS_y催化剂。通过调控硫掺杂量（y=0.1-0.5）和焙烧温度（300-600℃）,探究硫掺杂对催化剂物化性质与ECR性能的影响。实验表明,硫掺杂增大了催化剂的电荷转移速率,使催化剂的电化学活性表面积增大从而增强CO₂活化能力。在-1.0 V vs.RHE下,CuZnAlO_xS_0.3催化剂的CO法拉第效率达66.81%,较未掺杂硫元素的催化剂提升23.5%,同时析氢反应（HER）选择性降低至18.7%。此外,焙烧温度条件实验表明,经过500℃焙烧处理后的催化剂因金属氧化物相的结晶度最高而性能最优。采用等体积浸渍法对上述催化剂进行进一步改性,探究等体积浸渍法处理时,不同K₂CO₃添加量对催化剂ECR性能的影响。当K₂CO₃添加量为10%wt时,催化剂不仅恢复了部分类水滑石的层状结构,同时保留了金属氧化物相,有着更好的ECR活性。CZAOS-10%K₂CO₃催化剂在-0.9 V vs.RHE下CO的法拉第效率达到81.79%。LSV测试表明,催化剂相较于HER对ECR有着更低的过电势。此外,电解液种类（KOH与KHCO₃）与气体流速的协同优化研究表明,弱碱性的电解液更有利于ECR反应的发生,在适中的气体流速下产物的选择性更好。更多还原

【Abstract】 With the acceleration of global industrialization,the greenhouse effect caused by excessive carbon dioxide emissions has become a major environmental problem that threatens the sustainable development of mankind.Electrocatalytic carbon dioxide reduction（ECR）technology can convert CO₂ into high value-added chemicals(such as CO,formic acid,C₂₊hydrocarbons,etc.).By coupling renewable energy,it can accelerate the carbon cycle and is one of the key ways to help achieve the goal of carbon neutrality.Hydrotalcite-like materials have attracted much attention due to their advantages of adjustable metal cation types and proportions,large specific surface area,strong CO₂adsorption capacity,more reactive sites and rich Lewis base sites,but their ECR efficiency and product selectivity still need to be further improved.In this paper,copper-based LDH-derived oxides were used as the research object.Through sulfur doping and morphology control strategies,the optimization mechanism of catalyst ECR performance was systematically explored,which provided experimental guidance and theoretical basis for the design of efficient ECR catalysts.The CuZnAl-LDH precursor was synthesized by co-precipitation method,and the small molecule organic compound methyl isothiocyanate was introduced as the sulfur source.The CuZnAlO_xS_ycatalyst was obtained after calcination.The effects of sulfur doping on the physicochemical properties and ECR performance of the catalysts were investigated by adjusting the sulfur doping amount（y=0.1-0.5）and calcination temperature（300-600°C）.Experiments show that sulfur doping increases the charge transfer rate of the catalyst,increases the electrochemical active surface area of the catalyst,and enhances the CO₂ activation ability.At-1.0 V vs.RHE,the CO Faraday efficiency of the CuZnAlO_xS_0.3 catalyst reached 66.81%,which was 23.5%higher than that of the catalyst without sulfur doping,and the selectivity of hydrogen evolution reaction（HER）was reduced to 18.7%.In addition,the calcination temperature experiment shows that the catalyst calcined at 500°C has the best performance due to the highest crystallinity of the metal oxide phase.The above catalysts were further modified by equal volume impregnation method,and the effects of different K₂CO₃ additions on the ECR performance of the catalysts were investigated.When the addition amount of K₂CO₃ is 10%wt,the catalyst not only restores the layered structure of some hydrotalcite-like compounds,but also retains the metal oxide phase and has better ECR activity.The Faraday efficiency of CO on CZAOS-10%K₂CO₃catalyst reached 81.79%at-0.9 V vs.RHE.The LSV test shows that the catalyst has a lower overpotential for ECR than HER.In addition,the synergistic optimization of electrolyte types（KOH and KHCO₃）and gas flow rate showed that weakly alkaline electrolyte was more conducive to the occurrence of ECR reaction,and the selectivity of products was better at moderate gas flow rate.更多还原