Maximized Schottky Effect: The Ultrafine V O /Ni Heterojunctions Repeatedly Arranging on Monolayer Nanosheets for Efficient and Stable Water-to-Hydrogen Conversion.

The Mott-Schottky heterojunction formed at the interface of ultrafine metallic Ni and semiconducting V O nanoparticles is constructed, and the heterojunctions are "knitted" into the tulle-like monolayer nanosheets on nickel foam (NF). The greatly reduced particle sizes of both Ni and V O on the Mott-Schottky heterojunction highly enhance the number of Schottky heterojunctions per unit area of the materials. Moreover, arranging the heterojunctions into the monolayer nanosheets makes the heterojunctions repeat and expose to the electrolyte sufficiently. The Schottky heterojunctions are like countless self-powered charge transfer workstations embedded in the tulle-like monolayer nanosheets, promoting maximum of the materials to participate into the electron transfer and become catalytic active sites. In addition, the tulle-like monolayer nanosheet structure can assist in pumping liquid phase electrolyte to the surface of catalysts, owing to the capillary force. The V O /Ni/NF Mott-Schottky catalyst exhibits excellent hydrogen evolution reaction (HER) performance with a low η of 54 mV and needs -107 mV to get the current density of -100 mA cm . Furthermore, V O /Ni/NF Schottky electrocatalyst exhibits excellent urea oxidation reaction activity: 1.40, 1.51, and 1.61 V versus reversible hydrogen electrode (RHE) voltage are required to reach a current density of 100, 500, and 1000 mA cm , respectively.