Crystallinity-Directed In Situ Reconstruction of Cu-Al Oxides Yielding Tunable Cu Sites for Electrochemical CO-to-C Conversion.

During the electrochemical CO reduction reaction (CORR), copper catalysts continuously undergo structural evolution, which is less controllable, and its impact on the product distribution of CORR remains unclear. Here, crystallinity-tunable Cu-Al mixed metal oxide (CuAl-MMO-) precatalysts were first synthesized via layered double hydroxide calcination. These precatalysts subsequently underwent in situ electrochemical reconstruction to form active CuAl-MMO-R catalysts with tailored Cu valence states. The moderately crystalline-derived CuAl-MMO-600R achieves a C Faradaic efficiency of 76.8% with 44.6% ethylene selectivity at -300 mA·cm, 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-to-C conversion and biomass-derived chemical production. This crystallinity-directed reconstruction strategy provides a pathway to tailoring CORR electrocatalysts and controlling the product selectivity.