Intermetallic molybdenum disilicide: a new, active, and stable cocatalyst for efficient solar hydrogen production

Abstract

The exploration of active, durable, and cost-efficient cocatalysts is pivotal for developing effective photocatalysts/systems for sustainable photocatalytic H₂ production from water splitting. Herein, we report intermetallic molybdenum disilicide (MoSi₂) as a novel, active, and durable cocatalyst for the photocatalytic H₂ evolution reaction (HER) in a dye-sensitized photocatalytic system and on semiconductor photocatalysts. Density functional theory (DFT) calculations suggest that the Mo sites are the main active sites with a near-zero Gibbs free energy of hydrogen adsorption (ΔG_H = 0.02 eV), thus endowing MoSi₂ with favorable H₂ evolution kinetics and a lower overpotential. When sensitized with organic xanthene dyes, e.g., Erythrosin B (ErB), MoSi₂ can efficiently catalyze the photocatalytic HER with high activity and excellent cycling stability, and outperforms other Mo-based cocatalysts and transition metal disilicides. Furthermore, MoSi₂ also serves as an efficient and stable cocatalyst on inorganic semiconductor photocatalysts, such as CdS and TiO₂. This work demonstrates the great potential of transition metal silicides as efficient and low-cost H₂ evolution cocatalysts for constructing high-performance photocatalysts/systems for solar energy conversion.