Optimizing the Selectivity of CH Electrosynthesis from CO Over Cuprates Through Cu─O Bond Length Descriptor.

Precisely controlling the nature of Cu─O bond in Cu-based oxide catalysts and understanding its correlation with CH electrosynthesis (from CO) for selectivity optimization is a long-standing challenge. Herein, taking a specific type of cuprates structured with CuO square-planar motifs as the platform, we report a selectivity descriptor of Cu─O bond length for screening highly selective catalysts toward CH electrosynthesis. We establish the descriptor by systematic investigations of several proof-of-concept cuprates. Their Cu─O bond lengths are precisely controlled ranging from 1.944 to 1.970 Å and these bonds remain stable in CH selectivity evaluation. Our investigations demonstrate that the CH selectivity exhibits a volcano-type dependence on the Cu─O bond length, and the optimized value is accessible at about 1.951 Å. This could be attributed to the optimal (neither too strong nor too weak) *CO adsorption created by the moderate Cu─O bond length, facilitating *CO hydrogenation. Furthermore, utilizing this descriptor, we predict three highly selective cuprates for CH electrosynthesis, with superior selectivity that is near the top of the volcano plot. And importantly, in an acidic electrolyte (pH = 1), they outperform the reported catalysts, achieving CH selectivity of up to 61.7% at 300 mA cm.