Self-supported thin-film electrode consisting of transition metal borides for highly efficient hydrogen evolution

Abstract

Transition metal borides (TMBs) are a new class of promising electrocatalysts for hydrogen generation by water splitting. However, the synthesis of robust all-in-one electrodes is challenging for practical applications. Herein, a facile solid-state boronization strategy is reported to synthesize a series of self-supported TMBs thin films (TMB-TFs) with large area and high catalytic activity. Among them, MoB thin film (MoB-TF) exhibits the highest activity toward electrocatalytic hydrogen evolution reaction (HER), displaying a low overpotential (η₁₀ = 191 and 219 mV at 10 mA cm⁻²) and a small Tafel slope (60.25 and 61.91 mV dec⁻¹) in 0.5 M H₂SO₄ and 1.0 M KOH, respectively. Moreover, it outperforms the commercial Pt/C at the high current density region, demonstrating potential applications in industrially electrochemical water splitting. Theoretical study reveals that both surfaces terminated by TM and B atoms can serve as the active sites and the H* binding strength of TMBs is correlated with the p band center of B atoms. This work provides a new pathway for the potential application of TMBs in large-scale hydrogen production.