Surface engineering of phase controlled defective 1 T-MoS2 QDs@g-C3Nx material for significantly enhanced hydrogen evolution under visible-light irradiation

Abstract

Design and construction of non-precious metal photocatalysts are necessary to achieve excellent hydrogen evolution reaction (HER) performance and good stability in photocatalytic water splitting systems. Herein, the phase control and defect engineering are applied to fabricate metallic 1 T-phase molybdenum disulfide quantum dots (1 T-MoS2 QDs) decorated 2D g-C3Nx nanosheets with the feature of nitrogen vacancies (denoted as 1 T-MoS2 QDs@g-C3Nx) for photocatalytic HER. The introduction of N defects facilitates to design electronic and energy band structures of g-C3N4. MoS2 QDs is beneficial to improve the charge carrier transport performances in the composite system. And the synergistic effect of phase control and defect engineering can optimize the reaction dynamics of photocatalytic HER. The resultant 1 T-MoS2 QDs@g-C3Nx (15 wt%) shows excellent properties for photocatalytic H2 evolution, with highest H2 generation rate reaching 4.08 mmol g-1h−1. Significantly, the superior H2 production performance of 1 T-MoS2 QDs@g-C3Nx (15 wt%) are achieved, outperforming the benchmark photocatalyst Pt-loading g-C3Nx (2.69 mmol g-1h−1). In addition, 1 T-MoS2 QDs@g-C3Nx (15 wt%) also exhibits high and stable cycling and durability with no significant decay of photocatalytic H2 evolution under continuous 25 h of visible light irradiation (λ > 420 nm). Meanwhile, the possible HER mechanism is explained based on the electronic and energy band structures effects of the g-C3Nx and the 1 T-MoS2 QDs cocatalyst. This work presents an efficient strategy for tuning the optical properties of nitrogen-based photocatalyst to enhance solar energy capture and conversion.