Microwave-assisted molybdenum-nickel alloy for efficient water electrolysis under large current density through spillover and Fe doping

The development of high-efficiency electrocatalysts for overall water splitting under large current density is significant and challenging. Herein, a high-performing Fe-doped MoNi alloy catalyst (M-H-MoNiFe-50) abundant with flower-like nanorods assemblies has been prepared by high-pressure microwave reaction and hydrogen reduction. Firstly, Fe doped NiMoO₄ precursor (M-MoNiFe-50) was synthesized by microwave fast heating, ensuring the robustness of nanorods, which owns larger area and improved catalytic activity than that by conventional hydrothermal method. Secondly, M-MoNiFe-50 was reduced in H₂/Ar to fabricate Fe-incorporated MoNi₄ alloys (M-H-MoNiFe-50), greatly enhancing the conductivity and facilitating hydrogen/oxygen spillover. The final M-H-MoNiFe-50 exhibits remarkable activity for alkaline/acidic hydrogen evolution reaction and oxygen evolution reaction with low overpotential of 208 (alkaline), 254 (acid) and 347 mV at 1,000 mA·cm⁻². Moreover, an alkaline water electrolyzer is established using M-H-MoNiFe-50 as anode and cathode, generating a current density of 100 mA·cm⁻² at 1.58 V with encouraging durability of 50 h at 1,000 mA·cm⁻². The extraordinary water splitting performance can be chalked up to the large surface area, favorable charge transfer, modified electron distribution, intrinsic robustness as well as an efficient gas spillover of M-H-MoNiFe-50. The final electrocatalyst has great prospects for practical application and confirms the significance of Fe doping, microwave method and spillover effect for catalytic performance improvement.