In Situ Electrochemical Oxidation Synthesis of SyA-Cu/CuO/NF Heterostructure As Trifunctional Electrocatalyst for UOR, BOR, and HER at Industrial-Scale High Current Density

Abstract

The construction of bifunctional or trifunctional electrocatalysts with excellent performance for highly effective overall water splitting is highly desirable and extremely challenging. Herein, Cu-based metal–organic frameworks (MOFs) nanomaterials using syringic acid (SyA) as ligands are grown on nickel foam (NF) by a one-step solvothermal method, namely, the self-supported precursor (SyA-Cu/NF); further, a SyA-Cu/CuO/NF heterostructure is obtained by in situ electrochemical oxidation of these precursors, which is applied to the urea oxidation reaction (UOR) and benzyl alcohol oxidation reaction (BOR). The optimal SyA-Cu/CuO/NF heterostructure could reach 100 mA cm–2 on only applying 1.47 V (vs RHE) with a Tafel slope of 53 mV dec–1 for UOR and 1.44 V with a Tafel slope of 32 mV dec–1 for BOR. Furthermore, it also displays hydrogen evolution reaction (HER) activity, showing a low overpotential of 92 mV at 10 mA cm–2. Above all, coupling UOR and BOR, it is used as a bifunctional electrocatalyst for the overall water splitting, which can reach 10 mA cm–2 at 1.47 and 1.45 V, respectively. Therefore, this SyA-Cu/CuO/NF heterostructure is a potential trifunctional electrocatalyst for UOR, BOR, and HER due to its unique interface interaction between SyA-Cu/CuO and the intermediates/electrolyte.