Lv Zhenli, Ma Guorui, Mu Haiqiang, Guo Jiaxing, Zhu Min, Li Jing, Li Feng
State Key Laboratory of High-efficiency Coal Utilization and Green Chemical Engineering, School of Chemistry and Chemical Engineering, Ningxia University, Yinchuan 750021, Ningxia, China.
Liupanshan Laboratory, Yinchuan 750021, Ningxia, China.
J Colloid Interface Sci. 2025 Aug 15;692:137492. doi: 10.1016/j.jcis.2025.137492. Epub 2025 Mar 31.
The enhanced selectivity for C products in the electrochemical CO reduction reaction (ECORR) is critically dependent on the regulation of the elemental existence state on the surface of the electrocatalyst. In this study, CuO nanowires featuring multiple grain boundaries were successfully synthesized. Two distinct model catalysts were prepared: one through surface adsorption of Br (denoted as CuO_Br) and the other via surface bromination (denoted as CuO@CuBr). These models were employed to systematically investigate the influence of the differences between Br adsorption on the CuO surface and surface bromination on activity and product selectivity. The integration of in-situ characterization techniques with electrochemical measurements revealed that Br adsorption induces a stable charge distribution on the catalyst surface, accompanied by a consistent potential drop within the double layer. This signifies stable and efficient processes of CO adsorption, electron transfer, and mass transfer at the electrode/electrolyte interface. Under these conditions, CuO_Br exhibits high stability. In contrast, catalyst surfaces modified via surface bromination are prone to Br dissolution during electrolysis, leading to structural changes and significant surface reconstruction, which ultimately compromise the catalyst's selectivity. Notably, the CuO_Br catalyst achieved a maximum Faradaic efficiency (FE) of 98 % for CO production at -0.4 V vs. RHE and 42 % for CH production at -0.6 V vs. RHE. Additionally, the CuO_Br catalyst reached an optimal FE of 60 % at -0.6 V, which is 1.5 times higher than that of the pure CuO catalyst under the same potential and 2.5 times higher than that of the CuO@CuBr catalyst at -0.9 V. This work provides new insights into enhancing the selectivity and activity of carbon dioxide electroreduction by modulating halide ion adsorption on the catalyst surface and surface halogenation.
在电化学CO还原反应（ECORR）中，对C产物增强的选择性关键取决于对电催化剂表面元素存在状态的调控。在本研究中，成功合成了具有多个晶界的CuO纳米线。制备了两种不同的模型催化剂：一种通过Br的表面吸附（记为CuO_Br），另一种通过表面溴化（记为CuO@CuBr）。这些模型被用于系统研究CuO表面Br吸附与表面溴化之间的差异对活性和产物选择性的影响。原位表征技术与电化学测量的结合表明，Br吸附在催化剂表面诱导了稳定的电荷分布，同时双层内伴随着一致的电位降。这意味着在电极/电解质界面处CO吸附、电子转移和传质的稳定且高效的过程。在这些条件下，CuO_Br表现出高稳定性。相比之下，通过表面溴化改性的催化剂表面在电解过程中容易发生Br溶解，导致结构变化和显著的表面重构，最终损害了催化剂的选择性。值得注意的是，CuO_Br催化剂在相对于可逆氢电极（RHE）为-0.4 V时，CO生成的最大法拉第效率（FE）为98%，在相对于RHE为-0.6 V时，CH生成的FE为42%。此外，CuO_Br催化剂在-0.6 V时达到了60%的最佳FE，这比相同电位下的纯CuO催化剂高1.5倍，比-0.9 V时的CuO@CuBr催化剂高2.5倍。这项工作通过调节催化剂表面卤离子吸附和表面卤化，为提高二氧化碳电还原的选择性和活性提供了新的见解。
