Se-Ni(OH)2-shelled vertically oriented NiSe nanowires as a superior electrocatalyst toward urea oxidation reaction of fuel cells

Abstract The direct urea fuel cell holds great promise for energy-sustainable developments and mitigating water contamination but it still faces a great challenge to overcome the sluggish kinetics of the urea oxidation reaction (UOR). In this work, we report Se-Ni(OH) 2 -shelled vertically oriented NiSe nanowires on a Ni foam as an electrocatalyst toward UOR, showing a low potential of 0.366 V vs. SCE to drive 100 mA cm −2 in alkaline solution and out-performing all the reported non-noble-metal UOR catalysts up to date. Experimental results and theoretical calculation reveal that the vertically and distantly arranged nanowires with highly porous structure produce high mass transport paths for urea to fully access the reaction sites, the NiSe core offers high conductivity for fast electron transport, and the Se-Ni(OH) 2 shell provides large amount of active catalytic sites while lowering the CO 2 adsorption/desorption barrier than Ni(OH) 2 for fast reaction kinetics. This work opens up an exciting new direction to design electrocatalysts for high performance fuel cells and other energy applications.