Activating hexagonal boron nitride monolayers for efficient hydrogen evolution reaction by strong interfacial interactions with 2D M2X electrides

Abstract

Despite its fascinating properties, activating the inert basal plane of perfect hexagonal boron nitride (h-BN) monolayers for broader applications remains a significant challenge. Herein, we propose a promising strategy to activate the h-BN basal planes by anchoring them on a metal-based (M₂X, M = Ca, Sc, Sr, Y, Ba, and Hf; X= C, N, and S) electride substrate. Our comprehensive density functional theory (DFT) computations revealed the extensively strong adhesion of h-BN to these M₂X supports due to substantial hybridizations, guaranteeing the excellent thermal stability of anchored h-BN. As a result, a significant amount of electron transfer occurs from M₂X-based electrodes to h-BN, which not only greatly enhances the electrical conductivity of h-BN but also tunes the p-orbital electron occupancy of the B atoms to varying degrees, leading to controllable catalytic activity in the hydrogen evolution reactions (HER). In particular, the h-BN/Hf₂S heterostructure can perform as a promising HER catalyst, characterized by low free energies of H* adsorption (−0.07 eV) and a small kinetic barrier for H₂ production (0.12 eV) under acidic conditions. Our findings open new avenues for activating the inert h-BN monolayer, enriching its potential applications in electrocatalysis.