Crystallinity-Directed In Situ Reconstruction of Cu–Al Oxides Yielding Tunable Cu<sup>δ+</sup> Sites for Electrochemical CO<sub>2</sub>-to-C<sub>2+</sub> Conversion
Wenqing Zhang, Shulin Zhao, Xuerong Wang, Luyao Yang, Qianqian Zhao, Chunhao Jiang, Yuzhou Wang, Yuping Wu, Yuhui Chen
Abstract
During the electrochemical CO 2 reduction reaction (CO 2 RR), copper catalysts continuously undergo structural evolution, which is less controllable, and its impact on the product distribution of CO 2 RR remains unclear. Here, crystallinity-tunable Cu–Al mixed metal oxide (CuAl-MMO- T ) precatalysts were first synthesized via layered double hydroxide calcination. These precatalysts subsequently underwent in situ electrochemical reconstruction to form active CuAl-MMO- T R catalysts with tailored Cu δ+ valence states. The moderately crystalline-derived CuAl-MMO-600R achieves a C 2+ Faradaic efficiency of 76.8% with 44.6% ethylene selectivity at −300 mA·cm –2, outperforming both its low- and high-crystallinity counterparts. In situ Raman and density functional theory showed that residual Al species stabilize Cu + active sites via strong electronic interactions, while oxygen vacancies promote *CO adsorption and OH – enrichment, synergistically lowering the C–C coupling energy barrier. Furthermore, system integration assisted by the glycerol oxidation reaction reduces the full-cell voltage by 17%, enabling simultaneous CO 2 -to-C 2+ conversion and biomass-derived chemical production. This crystallinity-directed reconstruction strategy provides a pathway to tailoring CO 2 RR electrocatalysts and controlling the product selectivity.