Search

Homostructured rutile TiO2 nanotree arrays thin films with nitrogen doping were synthesized on FTO glass substrates via a two-step hydrothermal method. The crystal structure and morphology of nanotree arrays thin films were characterized by means of X-ray diffractometer and field-emission scanning electron microscopy. Furthermore, the optical and photoelectrochemical performance of nitrogen doped TiO2 nanotree arrays thin films was analyzed respectively using diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, linear sweep voltammetry, transient photocurrent and Mott–Schottky measurements. The results showed that nitrogen doping significantly affected the morphology of branched nanostructure, electron energy band structure, electron transportation and charge carrier recombination at the surface and interface of nanotrees. Optimized photoelectrochemical performance was achieved with relatively lower electron transport resistance and higher photocurrent density by the TiO2 nanotree arrays thin film with N/Ti molar ratio of 1, which can be mainly attributed to the formation of appropriate branched nanostructure to improve photoexcited electrons rate and new localized mid-gap states energy levels due to the nitrogen doping. [ABSTRACT FROM AUTHOR]

Due to the cost-effectiveness of sodium source, sodium-ion batteries (SIBs) have attracted considerable attention. However, SIBs still have some challenges in competing with lithium-ion batteries for practical applications. Particularly, the high rate capability and cycling stability are posing big problems for SIBs. Here, nitrogen-doped carbon-coated WS 2 nanosheets (WS 2 /NC) were successfully synthesized by a high-temperature solution method, followed by carbonization of polypyrrole. When used as anode electrodes for SIBs, WS 2 /NC composite exhibited high-rate capacity at 386 and 238.1 mAh g -1 at 50 and 2,000 mA g -1 , respectively. Furthermore, even after 400 cycle, the composite electrode could still deliver a capacity of ~180.1 mAh g -1 at 1,000 mA g -1 , corresponding to a capacity loss of 0.09% per cycle. The excellent electrochemical performance could be attributed to the synergistic effect of the highly conductive nature of the nitrogen-doped carbon-coating and WS 2 nanosheets. Results showed that the WS 2 /NC nanosheets are promising electrode materials for SIBs application.