Enhanced hydrogen production by carbon-doped TiO₂ decorated with reduced graphene oxide (rGO) under visible light irradiation

Enhancing visible light utilization by photocatalysts, avoiding electron-hole recombination, and facilitating charge transfer are three major challenges to the success of sustainable photocatalytic systems. In our study, carbon-doped TiO₂ was synthesized with decoration of reduced graphene oxide (C-TiO₂/rGO) to form a hybrid nanocomposite that exhibits excellent photocatalytic activity and longevity. Morphology, chemical and colloidal stability, crystallinity, surface compositions and band structures were systematically assessed. The results revealed that the hybrid C-TiO₂/rGO had a band gap of 2.2 ± 0.2 eV and crystallite sizes of 0.9-2 nm in diameter. Transmission electron microcopy (TEM) images showed that C-TiO₂ particles attached to the carbon sheet of rGO. Under irradiation of 135 mW cm^-2 at 400-690 nm with methanol as electron donor, C-TiO₂ and C-TiO₂/rGO yielded incredibly high H₂ production rates of 0.67 ± 0.12 to 1.50 ± 0.2 mmol g^-1 h^-1, respectively, which were greater than those of other titanium hybrid catalysts such as C-TiO₂/Pt. rGO not only greatly improved the photocatalytic activity but also led to greater stability of H₂ production compared to C-TiO₂. This work lays groundwork toward the design of novel visible light-driven photocatalytic systems for harnessing solar energy and environmental applications.