High‐performance Cu6Sn5 alloy electrocatalysts for formaldehyde oxidative dehydrogenation and bipolar hydrogen production

Aldehyde assisted water electrolysis offers an attractive pathway for energy‐saving bipolar hydrogen production with combined faradaic efficiency of 200 % while converting formaldehyde into value‐added formate. Herein we report the design and synthesis of noble metal free Cu6Sn5 alloy as a highly effective electrocatalyst for formaldehyde electro oxidative dehydrogenation, demonstrating a geometric current density of 915±46 mA/cm2 at 0.4 V vs. reversible hydrogen electrode, outperforming many noble metal electrocatalysts reported previously. The formaldehyde assisted water electrolyser delivers 100 mA/cm2 at a low cell voltage of 0.124 V, and a current density of 486±20 mA/cm2 at a cell voltage of 0.6 V without any iR compensation, and exhibit nearly 200 % faradaic efficiency for bipolar hydrogen production at 100 mA/cm2 in 88‐hour long‐term operation. Density functional theory calculations further confirm the notably lowered barriers for dehydrogenation and Tafel steps on the Cu₆Sn₅ surface compared to Cu, underscoring its potential as a highly active catalyst.