Mo Migration-Induced Crystalline to Amorphous Conversion and Formation of RuMo/NiMoO₄ Heterogeneous Nanoarray for Hydrazine-Assisted Water Splitting at Large Current Density

Manipulating the atomic structure of the catalyst and tailoring the dissociative water-hydrogen bonding network at the catalyst-electrolyte interface is essential for propelling alkaline hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR), but remains a great challenge. Herein, we constructed an advanced a-RuMo/NiMoO₄/NF heterogeneous electrocatalyst with amorphous RuMo alloy nanoclusters anchored to amorphous NiMoO₄ skeletons on Ni foam by a heteroatom implantation strategy. Theoretical calculations and in situ Raman tests show that the amorphous and alloying structure of a-RuMo/NiMoO₄/NF not only induces the directional evolution of interfacial H₂O, but also lowers the d-band center (from -0.43 to -2.22 eV) of a-RuMo/NiMoO₄/NF, the Gibbs free energy of hydrogen adsorption (ΔG_H*, from -1.29 to -0.06 eV), and the energy barrier of HzOR (ΔG_N2(g)=1.50 eV to ΔG_N2*=0.47 eV). Profiting from these favorable factors, the a-RuMo/NiMoO₄/NF exhibits excellent electrocatalytic performances, especially at large current densities, with an overpotential of 13 and 129 mV to reach 10 and 1000 mA cm^-2 for HER. While for HzOR, it needs only -91 and 276 mV to deliver 10 and 500 mA cm^-2, respectively. Further, the constructed a-RuMo/NiMoO₄/NF||a-RuMo/NiMoO₄/NF electrolyzer demands only 7 and 420 mV to afford 10 and 500 mA cm^-2.