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

Abstract 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 m_H2⁻³ 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.