Correlating the Valence State with the Adsorption Behavior of a Cu‐Based Electrocatalyst for Furfural Oxidation with Anodic Hydrogen Production Reaction

The low-potential furfural oxidation reaction (FFOR) on a Cu-based electrocatalyst can produce H₂ at the anode, thereby providing a bipolar H₂ production system with an ultralow cell voltage. However, the intrinsic activity and stability of the Cu-based electrocatalyst for the FFOR remain unsatisfactory for practical applications. This study investigates the correlation between the valence state and the adsorption behavior of the Cu-based electrocatalyst in furfural oxidation. Cu⁰ is the adsorption site with low intrinsic activity. Cu⁺ , which exists in the form of Cu(OH)ads in alkaline electrolytes, has no adsorption ability but can improve the performance of Cu⁰ by promoting the adsorption of FF. Moreover, a mixed-valence Cu-based electrocatalyst (MV Cu) with high intrinsic activity and stability is prepared electrochemically. With the MV Cu catalyst, the assembled dual-side H₂ production electrolyzer has a low electricity requirement of only 0.24 kWh mH2 ⁻³ at an ultralow cell voltage of 0.3 V, and it exhibits sufficient stability. This study not only correlates the valence state with the adsorption behavior of the Cu-based electrocatalyst for the low-potential FFOR with anodic H₂ production but also reveals the mechanism of deactivation to provide design principles for Cu-based electrocatalysts with satisfactory stability.