西安交通大学孔春才团队的研究报道了铜催化剂压缩应变——在电化学CO₂还原中增强C₂₊产物的生成。相关研究成果发表在2024年6月28日出版的《科学通报》。

Cu催化剂中的弹性应变增强了它们对电化学CO₂还原反应（eCO₂RR）的选择性，特别是对多碳（C₂₊）产物的形成的选择性。然而，这种选择性的原因和催化剂前体的作用尚未阐明。

该文中，研究人员采用氧化还原策略在Cu纳米晶体表面诱导应变。采用氧化转化法将Cu纳米晶转化为Cu_xO纳米晶；这些随后被电化学还原以形成Cu催化剂，同时保持它们的压缩应变。使用流动池配置，对于C₂₊产品实现了1A/cm²的电流密度和超过80%的法拉第效率。C₂₊/C1的选择性比也很显著，为9.9，比在拉伸应变下观察到的Cu催化剂的选择性比高出约7.6倍。

原位拉曼光谱和红外光谱显示，压缩应变Cu催化剂上K⁺离子水合水（K·H₂O）的覆盖率降低，这与分子动力学模拟和密度泛函理论计算一致。有限元法模拟证实，减少配位的K·H₂O水的覆盖率增加了中间反应物与表面相互作用的概率，从而促进了有效的C–C耦合，并提高了C₂₊产物的产率。这些发现为eCO₂RR中使用的Cu催化剂的靶向设计策略提供了有价值的见解。

附：英文原文

Title: Compressive strain in Cu catalysts: Enhancing generation of C2+ products in electrochemical CO2 reduction

Author: Jian Yang c, Chuncai Kong a

Issue&Volume: 2024/06/28

Abstract: Elastic strain in Cu catalysts enhances their selectivity for the electrochemical CO2 reduction reaction (eCO2RR), particularly toward the formation of multicarbon (C2+) products. However, the reasons for this selectivity and the effect of catalyst precursors have not yet been clarified. Hence, we employed a redox strategy to induce strain on the surface of Cu nanocrystals. Oxidative transformation was employed to convert Cu nanocrystals to CuxO nanocrystals; these were subsequently electrochemically reduced to form Cu catalysts, while maintaining their compressive strain. Using a flow cell configuration, a current density of 1 A/cm2 and Faradaic efficiency exceeding 80% were realized for the C2+ products. The selectivity ratio of C2+/C1 was also remarkable at 9.9, surpassing that observed for the Cu catalyst under tensile strain by approximately 7.6 times. In-situ Raman and infrared spectroscopy revealed a decrease in the coverage of K+ ion-hydrated water (K·H2O) on the compressively strained Cu catalysts, consistent with molecular dynamics simulations and density functional theory calculations. Finite element method simulations confirmed that reducing the coverage of coordinated K·H2O water increased the probability of intermediate reactants interacting with the surface, thereby promoting efficient C–C coupling and enhancing the yield of C2+ products. These findings provide valuable insights into targeted design strategies for Cu catalysts used in the eCO2RR.

DOI: 10.1016/j.scib.2024.06.031

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927324004560