A comprehensive study of the influence of sulfonated graphene sheets and CdS nanoparticles on the photocatalytic degradation and hydrogen evolution activities of TiO2 nanospheres.

Lack of clean water and energy crisis remain worldwide challenges. The preparation of efficient photocatalysts has been demonstrated to be a promising approach for environmental remediation and renewable energy production. In this work, sulfonated graphene oxide (SGO)-TiO2-CdS (STC) multi-component composites were delicately designed and synthesized through the hydrothermal method, combined with a two-phase mixing process. The influence of SGO sheets and CdS nanoparticles on the photodegradation and hydrogen evolution performances of TiO2 nanospheres was thoroughly studied. The photodegradation and hydrogen evolution efficiency of the STC composites were significantly improved in the presence of SGO and CdS as co-catalysts. STC-5, with the highest hydrogen evolution rate (15.835 mmol g-1 h-1), could generate 3167 µmol H2 within 120 min, which was much higher than those of SGO-TiO2, TiO2-CdS, and SGO-CdS. The SGO sheets and CdS nanoparticles could improve the light absorption and reduce the charge recombination rate of the TiO2 nanospheres concurrently, which were confirmed by UV-vis and PL spectroscopies and electrochemical measurements. The intrinsic superior properties of the STC composites contribute to the excellent photodegradation and hydrogen evolution activities. Hence, this study creates a rational avenue for the fabrication of multi-component composites and their applications in the industrial fields of wastewater purification and clean energy production.