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Z-scheme anatase/rutile TiO 2 /g-C 3 N 4 hybrids (denoted as LTARCN-x, x represents calcination temperature) were designed and synthesized by growing TiO 2 nanorods on the surface of g-C 3 N 4 utilizing impregnation-calcination method. Furthermore, through the etched effect of hydrochloric acid and calcination treatment, the as-prepared LTARCN-x possessed abundant pore structure and larger surface area, and the surface area of LTARCN-425 was 8.5 times than that of bulk g-C 3 N 4. Meanwhile, the g-C 3 N 4 would play a role of carrier to prevent from the aggregation of TiO 2 nanorods. In addition, under visible light irradiation, the Z-scheme heterostructure would be constructed between the rutile TiO 2 nanorod and g-C 3 N 4 nanosheet, respectively. The optimized photocatalyst LTARCN-425 exhibited a preferable activity, the photocatalytic hydrogen production rate of LTARCN-425 was about 1031 μmol g−1 h−1, and it was about 6.3 and 13.6 times than that of g-C 3 N 4 and TiO 2 , respectively. Moreover, the photocatalytic mechanism of the hydrogen production was studied intensively via designing fluorescent probe, Pt and PbO 2 deposition experiment, and the characterizations of EPR, TEM, HRTEM and XPS. [ABSTRACT FROM AUTHOR]

Low-temperature preparation of efficient electron transport layer (ETL) can effectively expand the application of perovskite solar cells (PSCs). We herein introduce anatase TiO 2 nanoparticles (NPs) with an average diameter of 15 nm prepared by hydrothermal method and optimized with acetic acid (AA) as well as oleic acid (OA). The Ti3+ as well as Ti–OH signals indicate the surface defects of TiO 2 NPs investigated by X-ray photoelectron spectroscopic (XPS) are observed to be passivated by the modifiers through chelate or bridging pattern. Thus, when the modified NPs are dispersed into the precursor for spin-coating ETLs under 150 °C, higher power conversion efficiency (PCE) of 20.15% and 19.41% is achieved based on planar structured PSC using TiO 2 modified with AA and OA, respectively. The device stability is also considerably increased. Analyzed by photoluminescence and electrochemical impedance spectroscopies, the improved cell performance can be ascribed to the reduced charge transport resistance, enhanced electron extraction, and suppressed recombination behavior. We anticipate this facile approach of fabricating efficient TiO 2 ETLs can be further employed into PSCs commercialization. [ABSTRACT FROM AUTHOR]

Abstract: The direct electrochemical reduction of titanium dioxide (TiO2) to metallic titanium at room temperature is firstly studied in Lewis basic AlCl3–1-butyl-3-methylimidizolium (AlCl3–BMIC) ionic liquid. In this study, cyclic voltammetry, potentiodynamic polarization, sampled current voltammetry and X-ray photoelectron spectroscopy (XPS) techniques were utilized. Analysis of the cyclic voltammetry suggested that TiO2 film can be reduced to metallic Ti. The sampled current voltammetry was applied to elaborate the reduction mechanism and the results showed that this reduction process may include two steps. When the output potential difference of 2.8V was applied, a TiO2 cylindrical pellet was partly reduced to metallic Ti. However, due to the very slow reaction rate, there was only about 12wt% of TiO2 was reduced during the electrolysis time of 48h. It was predicted that the process for the direct reduction of solid TiO2 would be explained as follows: given enough cathode potential, the reduction happened at the cathode/ionic liquids interface, where the oxygen was ionized, then dissolved in the ionic liquid and discharged at the anode, with the metallic Ti left at the cathode. [Copyright &y& Elsevier]