Heteroatom-Induced Accelerated Kinetics on Nickel Selenide for Highly Efficient Hydrazine-Assisted Water Splitting and Zn-Hydrazine Battery.

Highlights: Ultrathin P and Fe co-doped NiSe2 nanosheets supported on modified Ni foam are synthesized, which shows desirable bifunctional electrocatalytic hydrogen evolution reaction (HER)/hydrazine oxidation reaction (HzOR) performance in hydrazine-assisted water electrolysis and Zn-Hz battery. The coexistence of P and Fe heteroatoms induces an accelerated "2 + 2" reaction mechanism with a two-step HER process and a two-step HzOR step. Hydrazine-assisted water electrolysis is a promising energy conversion technology for highly efficient hydrogen production. Rational design of bifunctional electrocatalysts, which can simultaneously accelerate hydrogen evolution reaction (HER)/hydrazine oxidation reaction (HzOR) kinetics, is the key step. Herein, we demonstrate the development of ultrathin P/Fe co-doped NiSe2 nanosheets supported on modified Ni foam (P/Fe-NiSe2) synthesized through a facile electrodeposition process and subsequent heat treatment. Based on electrochemical measurements, characterizations, and density functional theory calculations, a favorable "2 + 2" reaction mechanism with a two-step HER process and a two-step HzOR step was fully proved and the specific effect of P doping on HzOR kinetics was investigated. P/Fe-NiSe2 thus yields an impressive electrocatalytic performance, delivering a high current density of 100 mA cm−2 with potentials of − 168 and 200 mV for HER and HzOR, respectively. Additionally, P/Fe-NiSe2 can work efficiently for hydrazine-assisted water electrolysis and Zn-Hydrazine (Zn-Hz) battery, making it promising for practical application. [ABSTRACT FROM AUTHOR]