Efficient Photocatalytic Reduction Approach for Synthesizing Chemically Bonded N-Doped TiO2/Reduced Graphene Oxide Hybrid as a Freestanding Electrode for High-Performance Lithium Storage

Covalent bonds between active materials and conductive substrates significantly facilitate rapid interfacial charge transfer, thus enhancing the lithium-ion storage performances of freestanding electrodes. Herein, an efficient photocatalytic reduction approach is developed to synthesize chemically bonded N-doped TiO2 nanowire/reduced graphene oxide (N-TiO2/RGO) hybrid as a freestanding electrode for ultrafast lithium storage. Ti3+-C bonds are formed during the ultraviolet photocatalytic reduction process, as corroborated by Raman, electron paramagnetic resonance, and X-ray photoelectron spectra. The NTiO2/RGO hybrid electrode exhibits a significantly higher rate capability than its counterpart without UV irradiation. After as long as 10,000 discharging/charging cycles, high capacities of 182.7, 125.1, and 101.8 mA h g(-1) are retained at current rates of 5, 25, and even up to 50 C (1 C = 335 mA g(-1)), respectively. The excellent electrochemical performances of the N-TiO2/RGO hybrid are attributed to the enhanced electronic conductivity and lithium-ion diffusion kinetics arising from the Ti3+-C bonds and the robust architecture of N-doped TiO2.