Highly efficient photocatalytic hydrogen generation of g-C₃N₄-CdS sheets based on plasmon-enhanced triplet–triplet annihilation upconversion

Herein we first coupled a wide photo-response photocatalyst with plasmon-enhanced triplet − triplet annihilation upconversion (TTA-UC) nanoparticles for photocatalytic hydrogen generation. The plasmon-based enhancement of TTA-UC was achieved by introducing Au nanoparticles into the core liquid of TTA-UC nanoparticles containing platinum(II)-octaethylporphyrin and 9,10-diphenylanthracene. Au-TTA nanoparticles encapsulated by silica shells significantly increased the green-to-blue upconversion compared with TTA nanoparticles. The silica shells after further surface functionalization can conjoin with photocatalysts. To improve the stability of cadmium sulfide (CdS), graphitic carbon nitride (g-C₃N₄) was combined with CdS for g-C₃N₄-CdS heterojunctions. g-C₃N₄-CdS sheets based on Au-enhanced TTA-UC can utilize the upconverted high-energy photons and thereby realized efficient photocatalytic hydrogen production. Au-TTA nanoparticles conjoined with g-C₃N₄-CdS reached a high hydrogen production of 16.88 mmol g⁻¹ under visible-light irradiation and an apparent quantum efficiency of 1.439% under green-light irradiation. The study provides a new TTA-supported upconversion-photocatalysis system enhanced by Au plasmon resonance effect for effectively hydrogen generation.