【作者】 刘豹；

【导师】 刘敏；

【作者基本信息】 中南大学 ， 凝聚态物理， 2022， 硕士

【摘要】 电化学二氧化碳还原（CO₂RR）可以将CO₂转换成高附加值碳氢燃料。开发具有较高活性和选择性的催化剂是促进CO₂有效资源化的重要方式。但目前催化剂普遍存在活性低和选择性差的问题,限制了CO₂资源化的进展。银、铜纳米材料具有优异的表面物理性质,拥有较高的催化活性。本文深入研究锡掺杂银（Ag/Sn）和多孔铜（P-Cu）纳米材料在CO₂RR中的反应机理,发现银、铜纳米材料分别通过局域电场增强和“空间限域”效应,提高CO₂RR催化活性和选择性。具体研究内容如下:（1）通过简单的共沉淀还原制备Ag/Sn纳米材料,探究Ag/Sn纳米材料局域电场对催化性能影响。理论计算表明Sn的引入会导致一个较强局域电场,局域电场会降低CO₂RR中*COOH的生成能垒。通过差相对比扫描透射电子显微镜（DCP-STEM）揭示了表面Ag/Sn纳米材料具有强局域电场空间分布。原位红外光谱证明局域电场能够增强CO₂RR过程中*COOH吸附。电催化CO₂RR测试表明,Ag/Sn纳米材料在一个宽的电位窗口（-0.5—-1.1 V vs RHE）内表现出对一氧化碳（CO）100%选择性。（2）采用液相还原制备P-Cu纳米材料,探究P-Cu产生的“空间限域”效应对催化活性的影响。通过COMSOL模拟结果证明在孔附近会产生较强电场,电场会产生“空间限域”效应。CO气体吸附实验表明P-Cu纳米材料能够有效富集CO,证明了“空间限域”增强*CO的吸附,从而提高C-C耦合效率。因此,电催化CO₂RR测试表明,P-Cu对C2产物法拉第效率为57.22%,约为实心铜纳米材料的2.5倍。本文包含图25幅,表格6个,参考文献132篇更多还原

【Abstract】 Electrochemical reduction of carbon dioxide（CO₂RR）can convert CO₂ into value-added hydrocarbon fuels.The development of catalysts with high activity and selectivity is an important way to promote the effective recycling of CO₂.However,the low activity and poor selectivity of catalysts greatly limit the utilization of CO₂ resource.Silver and copper nanomaterials with excellent surface physical properties exhibit high catalytic activity.In this work,the reaction mechanism of Ag/Sn and P-Cu nanomaterials in CO₂RR was investigated.It was found that the catalytic activity and selectivity of Ag and Cu nanomaterials was improved by the effect of local electric field enhancement and"spatial confinement",respectively.The main research works are shown as follows:（1）To investigate effect of local electric field on catalytic performance of Ag/Sn nanomaterials,Ag/Sn nanomaterial was prepared by simple coprecipitation reduction method.The theoretical calculation and simulation results demonstrate that heteroatom induces the enhanced local electric field,local electric field lower energy barrier of*COOH in CO₂RR reaction.The differential phase contrast-scanning transmission electron microscopy（DPC-STEM）revealed that there is a strong local electric field on Ag/Sn nanomaterials.In-situ attenuated total reflection infrared spectroscopy（ATR-IR）results indicate that the localized electric field enhances the adsorption of intermediate*COOH.Hence,the catalyst exhibits a～100%faradaic efficiency under the grand potentials（-0.5 to-1.1 V vs RHE）in CO₂RR.（2）To explore the effect of“spatial confinement”on catalytic activity,P-Cu nanomaterial was synthesized by liquid phase reduction method.COMSOL simulation results confirm that there is a strong local electric field,thus leading to the effect of“spatial confinement”.The CO gas sensor and temperature programmed desorption（TPD）tests prove that the P-Cu exhibits a great CO adsorption and enrichment capacity,which proves that the“spatial confinement”enhances the adsorption of*CO,thus improving the C-C coupling efficiency.As a result,P-Cu exhibits a high C2 selectivity with a Faradaic efficiency of 57.22%in CO₂RR,it is about 2.5-fold that of compact Cu nanomaterial.There are 25 figures,6 tables and 132 references更多还原