Dispersing small Ru nanoparticles into boron nitride remodified by reduced graphene oxide for high-efficient electrocatalytic hydrogen evolution reaction

Abstract

Ruthenium (Ru) electrocatalysts suffer from excessive aggregation during the hydrogen evolution reaction (HER), which hinders their practical application for hydrogen production. Hexagonal boron nitride (h-BN) is a potential carrier that could solve the above problem, but its wide band gap and low conductivity become obstacles. Herein, we provide a new, facile, low-cost, and effective strategy (killing two birds with one stone) to overcome the above issues. After modifying h-BN with reduced graphene oxide (rGO), a small amount of Ru nanoparticles (NPs) (2.2 %) are dispersed into BN with approximately uniform distribution and size control of Ru nanoparticles (∼3.85 nm). The strong synergy between Ru NPs and BN@C in the optimal Ru/BN@C (Ru wt.% = 2.22 %) electrocatalyst endows it an outstanding HER activity, with small HER overpotentials (η10 = 32 mV, 35 mV) and low Tafel slopes (33.89 mV dec−1, 37.66 mV dec−1) in both 1 M KOH and 0.5 M H2SO4 media, respectively, along with good long-term stability for 50 h. Based on density functional theory (DFT) calculations, the addition of Ru to BN has been successful in creating fresh active sites for H*, with good possible adsorption/desorption ability (ΔGH* = −0.24 eV) while preserving low water dissociation (ΔGb = 0.46 eV) in an alkaline environment. As a result, the Ru/BN composite exhibits outstanding HER activity in both acidic and alkaline conditions. Furthermore, this study provides, for the first time, a template-free strategy to develop a good and low-cost supporter (BN) for dispersing other noble metals and the formation of highly efficient HER/OER electrocatalysts.