Self-integrated effects of 2D ZnIn2S4 and amorphous Mo2C nanoparticles composite for promoting solar hydrogen generation

To maximize the performance of photocatalytic hydrogen production, photocatalysts need to be modified by various means such as energy band engineering and cocatalyst. Here, we propose a strategy of self-integrated effects for promoting photocatalysts performance. We firstly design and fabricate a 2D ZnIn2S4 and amorphous Mo2C nanoparticles composite photocatalyst by integrating heterojunction effect, cocatalyst effect and photothermal effect in one, and then demonstrate that self-integrated effects of Mo2C/ZnIn2S4 composite can greatly enhance photocatalytic hydrogen evolution. Based on in situ characterization techniques and theoretical calculations, we also establish that the photocatalytic mechanism of self-integrated effects consisting heterojunction effect, cocatalyst effect and photothermal effect is attributed to the increased absorption capacity, the enhanced carrier separation, the reduced ΔGH*, the more active sites, the increased electron density and the enhanced carrier's mobility. Especially, the contribution of photothermal effect can elevate temperature to accelerate the photocatalytic reaction and the photothermal contribution exceeds 100% under irradiation. Consequently, 2D ZnIn2S4/amorphous Mo2C nanoparticles has a remarkable photocatalytic hydrogen evolution rate respectively up to 22.11 and 40.93 mmol/g/h upon visible and AM1.5 illumination, promoting 164% and 156% for the available values reported of modified ZnIn2S4 photocatalysts so far. These findings suggest that the proposed self-integrated effects can greatly promote photocatalytic hydrogen production.