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

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 mmol 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 H-2 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.