Mesoporous black TiO2/MoS2/Cu2S hierarchical tandem heterojunctions toward optimized photothermal-photocatalytic fuel production

Abstract

Mesoporous black TiO2/MoS2/Cu2S (b-TiO2/MoS2/Cu2S) hierarchical tandem heterojunctions visible-light photocatalysts are fabricated through evaporation-induced self-assembly, high-temperature hydrogenation, and solvothermal strategies. Mesoporous black TiO2 (b-TiO2) serves as the host to assemble MoS2 and Cu2S, which could absorb near-infrared energy to enhance photothermal effect. MoS2 nanosheets with vertical growth on b-TiO2 not only act as co-catalyst but also serve as a bridge to integrate mesoporous black TiO2 microspheres and Cu2S nanoparticles in tandem systems, thereby can effectively transfer and separate photogenerated charge carriers. The visible-light photocatalytic hydrogen production rate of the b-TiO2/MoS2/Cu2S without any precious metals cocatalysts is as high as 3376.7 μmol h−1 g−1, which is about 16 times higher than that of b-TiO2. The excellent photocatalytic performance could be ascribed to the formation of hierarchical tandem heterojunctions with suitable band gap alignment favoring charge transfer and separation, and the introduction of MoS2 and Cu2S extending photoresponse to NIR region. In addition, both MoS2 and Cu2S with narrow band gap could convert solar light into heat energy, which further promotes photocatalytic performance. The designed strategy could provide new insights for fabricating other tandem heterojunctions with high-performance for solar energy conversion.