Cocatalyst Engineering with Robust Tunable Carbon-Encapsulated Mo-Rich Mo/Mo2C Heterostructure Nanoparticle for Efficient Photocatalytic Hydrogen Evolution

Abstract

Cocatalyst engineering with non-noble metal nanomaterials can play a vital role in low-cost, sustainable, and large-scale photocatalytic hydrogen production. This research adopts slow carburization and simultaneous hydrocarbon reduction to synthesize carbon-encapsulated Mo/Mo2C heterostructure nanoparticles, namely Mo/Mo2C@C cocatalyst. Experimental and theoretical investigations indicate that the Mo/Mo2C@C cocatalysts have a nearly ideal hydrogen-adsorption free energy (ΔGH*), which results in the accelerated HER kinetics. As such, the cocatalysts are immobilized onto organic polymer semiconductor g-C3N4 and inorganic semiconductor CdS, resulting in Mo/Mo2C@C/g-C3N4 and Mo/Mo2C@C/CdS catalysts, respectively. In photocatalytic hydrogen evolution application under visible light, the Mo/Mo2C@C with g-C3N4 and CdS can form the Schottky junctions via appropriate band alignment, greatly suppressing the recombination of photoinduced electron-hole pairs. The surface carbon layer as the conducting scaffolds and Mo metal facilitates electron transfer and electron-hole separation, favoring structural stability and offering more reaction sites and interfaces as electron mediators. As a result, these catalysts exhibit high H2 production rates of 2.7 mmol h−1 g−1 in basic solution and 98.2 mmol h−1 g−1 in acidic solution, respectively, which is significantly higher than that of the bench-mark Pt-containing catalyst. The proposed cocatalyst engineering approach is promising in developing efficient non-noble metal cocatalysts for rapid hydrogen production.