Ni-doped TiO2 nanocubes wrapped by CNTs for synergic photocatalytic CH4 conversion

Direct conversion of CH 4 to high valued chemicals under mild conditions is attractive but full of challenges. Here, we present a ternary composite that consists of Ni-doped TiO 2 nanocubes (NCs) and CNTs as a new kind of catalyst (denoted as CNTs-Ni@TiO 2 NCs) for CH 4 photocatalytic conversion to C1 oxygenated products at 30 °C. Using H 2 O 2 as an oxidant, a high C1 oxygenated products yield and selectivity of 1.43 mol/(mol Ni ·h) and 95.6% can be reached in 2 h at 30 °C. The superior photocatalytic performance resulted from the synergistic effects of TiO 2 NCs, Ni species, and CNTs such as enhanced visible light absorption , improved electron/hole separation and charge transfer property, and lowered C-H bond cleavage energy required for CH 4 activation, were carefully studied. Good reusability of the catalyst was studied by recycle experiments. Possible reaction mechanism based on the radical routes were carefully discussed by combining in-situ Fourier transform infrared spectroscopy , X-ray photoelectron spectroscopy, electron spin resonance spectroscopy, radical scavenger experiments and density functional theory calculation.