Surface reconstruction and directed electron transport in NiSe2/MoSe2 Mott-Schottky heterojunction catalysts promote urea-assisted water splitting

The construction of cost-effective electrocatalysts with remarkable activity and durability for the urea oxidation reaction (UOR) is urgently needed to achieve sustainable hydrogen production. Herein, a three-dimensional (3D) nanostructure with uniform NiSe2/MoSe2 Mott-Schottky heterojunction nanoneedle arrays densely grown on carbon cloth was designed and fabricated by a hydrothermal method followed by selenization treatment. In the UOR process, NiSe2/MoSe2 undergoes surface reconstruction into a Mo-NiOOH/NiSe2 composite structure, and Mo-doping can optimize the adsorption/desorption of UOR intermediates. In the hydrogen evolution reaction (HER) process, the directed electron transfer brought by the Mott-Schottky heterojunction can modulate the electronic structure and optimize the d-band center, thus promoting HER. The well-designed NiSe2/MoSe2 as a bifunctional catalyst for urea-assisted electrolysis can reach 10 mA cm-2 at only 1.44 V with almost no performance degradation for 48 h. This work provides a promising avenue to develop efficient HER/UOR bifunctional catalysts toward urea-assisted water electrolysis.