Urchin-like TiO2/CdS Nanoparticles Forming an S-scheme Heterojunction for Photocatalytic Hydrogen Production and CO2 Reduction

The use of semiconductor nanoparticle heterojunctions for photocatalytic activities is a very attractive strategy. TiO2/CdS is widely used in the photocatalytic degradation of pollutants, but there are few reports on photocatalytic hydrogen production and CO2 reduction. In this work, rod and fishbone CdS nanoparticles were prepared by the hydrothermal method, and S-scheme TiO2/CdS nanoparticles with sea urchin morphology were designed. With Na2S and Na2SO3 as sacrifice agents, the H2 yield of TiO2/CdS was 1.07 mmol·h–1·g–1, and with [Ru(bpy)3]Cl2·6H2O as the photosensitizer and TEOA as the sacrifice agent, the rate of CO production from CO2 reduction was 47.67 μmol·h–1·g–1. The preparation rates of H2 and CO were 9 times and 13.3 times for TiO2 nanoparticles and 3.1 times and 1.7 times for fishbone CdS/TiO2 composite particles, respectively. The electron transfer path and photocatalytic mechanism were deduced by EPR, TRPL, UPS, etc. The results showed that the construction of the S-scheme heterojunction enhanced the photocatalytic performance of the catalyst. We synthesized the S-scheme TiO2/CdS nanoparticle heterojunction for the first time and applied it to the photocatalytic production of H2 and reduction of CO2. This work provides an effective reference for designing high-performance inorganic S-scheme heterojunction catalysts.