In-Plane Mott-Schottky Effects Enabling Efficient Hydrogen Evolution from Mo N -MoS Heterojunction Nanosheets in Universal-pH Electrolytes.

Cost-effective electrocatalysts for the hydrogen evolution reaction (HER) spanning a wide pH range are highly desirable but still challenging for hydrogen production via electrochemical water splitting. Herein, Mo N -MoS heterojunction nanosheets prepared on hollow carbon nanoribbons (Mo N -MoS /HCNRs) are designed as Mott-Schottky electrocatalysts for efficient pH-universal HER. The in-plane Mo N -MoS Mott-Schottky heterointerface induces electron redistribution and a built-in electric field, which effectively activates the inert MoS basal planes to intrinsically increase the electrocatalytic activity, improve electronic conductivity, and boost water dissociation activity. Moreover, the vertical Mo N -MoS nanosheets provide more activated sites for the electrochemical reaction and facilitate mass/electrolyte transport, while the tightly coupled HCNRs substrate and metallic Mo N provide fast electron transfer paths. Consequently, the Mo N -MoS /HCNRs electrocatalyst delivers excellent pH-universal HER performances exemplified by ultralow overpotentials of 57, 59, and 53 mV at a current density of 10 mA cm in acidic, neutral, and alkaline electrolytes with Tafel slopes of 38.4, 43.5, and 37.9 mV dec , respectively, which are superior to those of the reported MoS -based catalysts and outperform Pt in overall water splitting. This work proposes a new strategy to construct an in-plane heterointerface on the nanoscale and provides fresh insights into the HER electrocatalytic mechanism of MoS -based heterostructures.