Enhanced Photocatalytic Hydrogen Evolution from Organic Ternary Heterojunction Nanoparticles Featuring a Compact Alloy-Like Phase

Organic semiconductor nanoparticles (NPs) are attractive photocatalysts to produce hydrogen from water splitting. Herein, a ternary strategy of incorporating crystalline n-type molecule IDMIC-4F into the host system made of p-type polymer PM6 and n-type molecule ITCC-M is demonstrated. ITCC-M and IDMIC-4F form compact alloy-like composite with shorter lattice spacing in the ternary p/n heterojunction NPs, resulting in enhanced exciton dissociation and charge transfer characteristics. As the result, an unprecedented hydrogen evolution rate (HER) of 307 mmol h(-1) g(-1) and a maximum apparent quantum efficiency of 5.9% at 600 nm are achieved in the optimized ternary NPs (PM6:ITCC-M:IDMIC-4F = 1:1.3:0.2), which is among the highest HER from organic photocatalysts to the best of the authors' knowledge. The alloy-like composite also improves the operational stability of ternary NP photocatalysts. This work shows that synergizing two compatible n-type small molecules to form alloy-like composite is a promising approach to design novel organic photocatalysts for boosting the photocatalytic hydrogen evolution efficiency.

Automated summary

By incorporating crystalline n-type molecule IDMIC-4F into the host system made of p-type polymer PM6 and n-type molecule ITCC-M, a ternary strategy is demonstrated for enhancing the photocatalytic hydrogen evolution efficiency. The compact alloy-like composite formed by ITCC-M and IDMIC-4F in the ternary p/n heterojunction NPs improves exciton dissociation and charge transfer characteristics. The optimized ternary NPs achieve an unprecedented hydrogen evolution rate of 307 mmol h(-1) g(-1) and a maximum apparent quantum efficiency of 5.9% at 600 nm.