A novel yet simple strategy to fabricate visible light responsive C,N-TiO2/g-C3N4 heterostructures with significantly enhanced photocatalytic hydrogen generation

Abstract

In this report, we first successfully designed and fabricated novel C,N co-doped titanium dioxide nanoparticles/graphite-like carbon nitrogen ultrathin nanosheets (C,N-TiO₂ NPs/g-C₃N₄) heterostructures, wherein the C,N-TiO₂ NPs were in situ grown on the porous g-C₃N₄ ultrathin nanosheets (NSs) by a simple one-pot solvothermal route with the assistance of concentrated nitric acid. The resulting C,N-TiO₂ NPs/g-C₃N₄ nanocomposite photocatalysts were systematically characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, transient photocurrent–time (I–t) curves and electrochemical impedance spectroscopy (EIS) Nyquist plots. The photocatalytic ability was evaluated by photocatalytic water splitting for hydrogen evolution. These studies indicate that C,N-TiO₂ NPs/g-C₃N₄ composites exhibit superior ability for hydrogen generation compared to single C,N-TiO₂ NPs and pure g-C₃N₄ NSs under visible light illumination. The optimal composites with 3 wt% C,N-TiO₂ NPs/g-C₃N₄ showed the highest hydrogen evolution rate of 39.18 μmol g⁻¹ h⁻¹, which is about 10.9 and 21.3 times higher than those of C,N-TiO₂ NPs and pure g-C₃N₄ NSs, respectively. The improved photocatalytic H₂ evolution can be attributed to improved optical absorption and the lengthening lifetime of charge carrier pairs as a result of the C,N elemental codoping and the construction of intimate heterogeneous interfaces. This simple and feasible method for the fabrication of highly-efficient visible light responsive catalysts provides a great applied potential in energy generation.