Electrocatalytic conversion of carbon dioxide (CO₂) to methane (CH₄) has drawn great attention for solving the problem of global warming by reducing greenhouse gases and recycling carbon resources. Among reported Cu-based catalysts, Cu nanosheets (Cu NSs) with a highly exposed (111) facet are beneficial for converting CO₂ to CH₄. However, the stability issue of Cu NSs, due to their dissolution, severely limits their performance and practical application in electrocatalytic CO₂ reduction. Here, we report a method to effectively passivate the dissolution of Cu NSs by adding an appropriate amount of Cu²⁺ in the electrolyte, which improves the selectivity and stability of CO₂ reduction to CH₄. Structural characterization and CO₂ reduction tests indicate that the Cu NSs maintain the exposed (111) facet and thus maintain the efficient reduction of CO₂ to CH₄ in the electrolyte containing an appropriate Cu²⁺ concentration. The Cu NSs exhibit a high CH₄ selectivity of ∼70% and a high stability of ∼60% for ∼10 h. This work indicates that a moderate amount of Cu²⁺ in the electrolyte can passivate the Cu dissolution and increase the stability of Cu electrodes, providing a new perspective for achieving better stability of catalysts in the future.

中文翻译：

---

用含 Cu2+ 的电解质钝化 Cu 纳米片溶解以将 CO2 选择性电还原为 CH4

将二氧化碳（CO ₂）电催化转化为甲烷（CH ₄），通过减少温室气体排放和循环利用碳资源来解决全球变暖问题引起了人们的极大关注。在已报道的铜基催化剂中，具有高度暴露 (111) 晶面的铜纳米片 (Cu NSs) 有利于将 CO ₂转化为 CH ₄。然而，由于Cu NSs的溶解性问题，其稳定性问题严重限制了其在电催化CO ₂还原中的性能和实际应用。在这里，我们报道了一种通过在电解液中添加适量的 Cu ²⁺来有效钝化 Cu NSs 溶解的方法，该方法提高了 CO 的选择性和稳定性。₂还原为 CH ₄。结构表征和CO ₂还原测试表明，Cu NSs 保持了暴露的(111) 晶面，因此在含有适当Cu ²⁺浓度_{的电解液中保持了CO 2}到CH _{4的有效还原。}Cu NSs表现出~70%的高CH ₄选择性和~60%的高稳定性~10小时。该工作表明，电解液中适量的Cu ²⁺可以钝化Cu的溶解，提高Cu电极的稳定性，为未来获得更好的催化剂稳定性提供了新的视角。