Boosting the photocatalytic activity of graphite carbon nitride by designing novel MoS2–transition metal heterojunction cocatalysts

Abstract

The design of highly effective noble metal-free cocatalysts plays an extremely important role in improving the photocatalytic solar energy conversion. Herein, we designed and synthesized a novel heterostructure form of MoS₂–transition metals (Fe, Co, and Ni) on g-C₃N₄ nanosheets for obtaining a significant enhancement in the photocatalytic activity for hydrogen production and pollutant disposal. The electrochemical characterization and time-resolved photoluminescence results indicated that the unique tunable feature of the MoS₂–transition metals greatly reduced the hydrogen evolution reaction (HER) overpotential, increased the separation, transport and utilization efficiency of the photo-generated charge carriers, and displayed a synergistic effect in improving the electrocatalytic and photocatalytic HER performances. The ternary g-C₃N₄–MoS₂–metals exhibited extremely high photocatalytic HER rates of 1.7, 4.1, and 5.12 mmol h⁻¹ g⁻¹ for g-C₃N₄–MoS₂–Fe, g-C₃N₄–MoS₂–Co and g-C₃N₄–MoS₂–Ni, respectively, which were 2.7, 4.7 and 5.3 times larger than the sum of the photocatalytic HER activities of g-C₃N₄–MoS₂ and the corresponding g-C₃N₄–metals. This work provides a facile and effective strategy for improving photocatalytic energy conversion using only earth-abundant non-noble cocatalyst heterostructures.