In situ electronic redistribution of NiCoZnP/NF heterostructure via Fe-doping for boosting hydrazine oxidation and hydrogen evolution

Abstract

Water-splitting coupled with the hydrazine oxidation reaction (HzOR) is a remarkably important strategy for H₂ production, but remains a challenge. Herein, a Fe-doped Ni₂P-Co₂P-Zn₃P₂ heterogeneous electrocatalyst with a nanoneedle-assembled nanosphere structure and abundant defects was fabricated on Ni foam (Fe-NiCoZnP/NF). The introduction of Fe can tune the electron structure of NiCoZnP/NF, leading to a modulation of the d-band center towards the Fermi level, hence optimizing the free energy of hydrogen (ΔG_H*) and dehydrogenation behavior of hydrazine, and thereby realizing splendid HER and HzOR activities. The fabricated Fe-NiCoZnP/NF catalyst displays outstanding HER and HzOR activity and durability, with potentials of 121 and 13 mV vs. RHE to drive 1000 mA cm⁻² and Tafel slopes of 31.2 and 11.9 mV dec⁻¹, respectively, and a long durability of 120 h to achieve 100 mA cm⁻². Impressively, overall water–hydrazine electrolysis employing Fe-NiCoZnP/NF as the anodic and cathodic electrodes only requires low voltages of 1.92 and 2.67 V to achieve 100 and 1000 mA cm⁻², respectively, with a high stability for 120 h operation time during overall hydrazine splitting (OHzS). This work offers a justification for the design of high-efficiency bifunctional catalysts, and promotes energy-saving industry-level hydrogen generation.