Transition Metal-Doped Cobalt Phosphide for Efficient Hydrazine Oxidation: A Density Functional Theory Study

Abstract

Hydrazine oxidation reaction (HzOR) provides a sustainable alternative to the sluggish oxygen evolution reaction (OER), with a low theoretical thermodynamic potential (−0.33 V vs. RHE). However, developing efficient non-precious-metal catalysts for HzOR remains challenging. Here, we employed density functional theory (DFT) simulations to systematically investigate the mechanism of transition metal atoms doping (Au, Cr, Fe, Mn, Mo, Ni, Pd, Pt) to boost the N-H bond cleavage in HzOR. Among the studied dopants, Cr and Mn exhibit exceptional catalytic activity, achieving ultralow ΔG for RDS of −0.02 eV (CoP-Cr) and 0.02 eV (CoP-Mn), significantly lower than the high-coordination cobalt sites on undoped CoP (0.11 eV). CoP-Cr aligns with descriptor-driven optimization, while CoP-Mn operates via dopant-induced charge redistribution. Furthermore, we identified the adsorption free energy of N–NH₂ (ΔG_ad-N2H2-1) as a robust descriptor for catalytic activity in the reaction pathway involving distal configuration, showing strong correlations with ΔG of RDS. This work proposed a dual design strategy—descriptor-driven optimization (CoP-Cr) and charge-redistribution enhancement (CoP-Mn)—as a roadmap for developing earth-abundant, high-performance catalysts. These insights pave the way for advancing sustainable hydrogen production and environmental remediation technologies.