Elucidating the structure-dependent selectivity towards methane and ethanol of CuZn in the CO2 electroreduction using tailored Cu/ZnO precatalysts

Understanding the catalyst compositional and structural features that control selectivity is of uttermost importance to target desired products in chemical reactions. In this joint experimental–computational work, we leverage tailored Cu/ZnO precatalysts as a material platform to identify the intrinsic features of methane-producing and ethanol-producing CuZn catalysts in the electrochemical CO2 reduction reaction (CO2RR). Specifically, we find that Cu@ZnO nanocrystals, where a central Cu domain is decorated with ZnO domains, and ZnO@Cu nanocrystals, where a central ZnO domain is decorated with Cu domains, evolve into Cu@CuZn core@shell catalysts that are selective for methane (∼52%) and ethanol (∼39%), respectively. Operando X-ray absorption spectroscopy and various microscopy methods evidence that a higher degree of surface alloying along with a higher concentration of metallic Zn improve the ethanol selectivity. Density functional theory explains that the combination of electronic and tandem effects accounts for such selectivity. These findings mark a step ahead towards understanding structure–property relationships in bimetallic catalysts for the CO2RR and their rational tuning to increase selectivity towards target products, especially alcohols.

深刻洞察调控选择性以指向特定化学产物之关键性的催化剂组成与结构特征，实为化学变换领域之至高要义。在本项联合实验与计算研究中，我们以精心设计的 Cu/ZnO 预催化剂作为材料平台，旨在识别电化学 CO2 还原反应（CO2RR）中产生甲烷和乙醇的 CuZn 催化剂的固有特性。具体而言，我们发现，Cu@ZnO 纳米晶体，其中中心 Cu 区域被 ZnO 区域所装饰，以及 ZnO@Cu 纳米晶体，其中中心 ZnO 区域被 Cu 区域所装饰，经过演变形成了对甲烷（约 52%）和乙醇（约 39%）具有选择性的 Cu@CuZn 核壳催化剂。原位 X 射线吸收光谱和多种显微镜技术证实，表面合金化程度的提高以及金属 Zn 浓度的增加有助于提升乙醇的选择性。密度泛函理论阐释，电子效应与串联效应的结合解释了这种选择性。这些发现标志着我们理解 CO2RR 中双金属催化剂的结构-性质关系，以及其理性调控以增加对目标产物，尤其是醇类产物的选择性的重要一步。