Phase regulation of Ni(OH) nanosheets induced by W doping as self-supporting electrodes for boosted water electrolysis.

Developing high-performance and low-cost electrodes for hydrogen and oxygen evolution reactions (HER and OER, respectively) represents a pivotal challenge in the field of water electrolysis. Herein, W doped NiFe LDH nanosheets (NiFe-W/NF) were immobilized on nickel foam (NF) through one-step corrosion engineering, which induced the coexistence of α-Ni(OH) and β-Ni(OH). The doping of large atomic radius W influenced the growth of crystal planes of Ni(OH), promoting the formation of α-Ni(OH), which results in large layer spaces and neatly arranged nanosheets structure. The optimized NiFe-W/NF catalyst require potentials of only 69 to attain 10 mA/cm for HER, and require overpotentials of 269 mV to reach 100 mA/cm current density for OER, respectively. The W with high oxidation state can withdraw neighboring electrons from Ni, altering the adsorption energy of hydrogen intermediates, which improves the Volmer step and electrical conductivity in HER. And the large layer space of α-Ni(OH) in NiFe-W/NF can be contributed to accelerating the formation of high valence γ-NiOOH, which can accelerate OER kinetics. In addition, the NiFe-W/NF catalyst also provides an overall water splitting activity of 780 mA/cm current density at a cell voltage of only 1.90 V, and remains highly stable for over 70 h at 100 mA/cm, which makes it a bifunctional efficient catalyst for water electrolysis.