Spatially separated redox active sites over Re-Ni@Ni(OH)2 core-shell structure for enhancing furfural oxidation coupled with hydrogen evolution

An extremely high-efficiency bifunctional electrocatalyst with spatially separated redox active sites of Re-Ni@Ni(OH) 2 /CC is designed for furfural oxidation reaction coupling with hydrogen evolution reaction , which dramatically reduces the cell voltage required for FOR||HER and facilitates the production of value-added chemicals and hydrogen compared to pristine Ni@Ni(OH) 2 /CC. • Spatially separated active sites of Re-Ni@Ni(OH) 2 core-shell structure are designed. • Re modulates electronic structure of Ni and optimizes core-shell heterointerface. • Re-Ni sites at heterointerface improves the electron transfer kinetics for HER. • Optimized Ni(OH) 2 sites at Re-Ni@Ni(OH) 2 heterointerface enhances FOR performance. The design of bifunctional catalysts with spatially separated active sites holds significance importance in achieving simultaneous electrooxidation and hydrogen evolution reaction (HER). Herein, a core-shell Re-Ni@Ni(OH) 2 /CC heterostructure is demonstrated for the electrocatalytic furfural oxidation reaction (FOR) coupled with HER. Experimental results and theoretical analyses reveal that Re not only modulates the heterointerface between Re-Ni core and Ni(OH) 2 shell, facilitating furfural (FF) adsorption at Ni(OH) 2 sites, but also regulates electronic structure of Ni. This leads to a negative shift in the d-band center from Fermi level, effectively weakening hydrogen adsorption at Ni sites in Re-Ni@Ni(OH) 2 heterostructure, thereby improving the HER process. As a result, the synthesized Re-Ni@Ni(OH) 2 /CC exhibits a low cell voltage of 1.40 V @10 mA cm −2 for the FOR||HER. This study highlights the importance of modulating metal’s electronic structure and identifying active sites, which has great potential for improving bifunctional electrocatalytic reactions.