Sulfur-Modified Nickel-Based Hybrid Nanosheet as a Robust Bifunctional Electrode for Hydrogen Generation via Formaldehyde Reforming

Coupling the electrochemical oxidative upgrading of formaldehyde (FOR) with hydrogen evolution reaction (HER) toward energy-efficient H 2 production and simultaneous chemical production is important, but it still faces huge challenges. Herein, a unique hierarchical heterojunction is designed by coupling a Ni(OH) 2 nanosheet with S-modified Ni species on a nickel foam substrate (S–Ni@Ni(OH) 2 /NF) via a two-step strategy. The Ni(OH) 2 nanosheets with a large surface area contribute to offering sufficient sites for the grafting of S–Ni species, constructing a coupled heterostructure to realize greatly improved reaction kinetics for both HER and FOR processes. As a result, S–Ni@Ni(OH) 2 /NF delivers an overpotential of 50 mV for HER at 10 mA cm –2 and a low potential of 1.36 V to acquire a current density of 50 mA cm –2 for FOR. For the HER||FOR-coupled system, the built-in electrolyzer only needs 1.58 V to realize 50 mA cm –2 as well as superior stability. This work presents a facile strategy to exploit bifunctional electrodes for hydrogen generation via an energy-saving way with coupled formaldehyde reforming.