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

Abstract

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.