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

Abstract 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/NiMoO 4 /NF heterogeneous electrocatalyst with amorphous RuMo alloy nanoclusters anchored to amorphous NiMoO 4 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/NiMoO 4 /NF not only induces the directional evolution of interfacial H 2 O, but also lowers the d‐band center (from −0.43 to −2.22 eV) of a‐RuMo/NiMoO 4 /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/NiMoO 4 /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/NiMoO 4 /NF||a‐RuMo/NiMoO 4 /NF electrolyzer demands only 7 and 420 mV to afford 10 and 500 mA cm −2 .