Comprehension of the Synergistic Effect between m&t-BiVO 4 /TiO 2 -NTAs Nano-Heterostructures and Oxygen Vacancy for Elevated Charge Transfer and Enhanced Photoelectrochemical Performances.

Through the utilization of a facile procedure combined with anodization and hydrothermal synthesis, highly ordered alignment TiO 2 nanotube arrays (TiO 2 -NTAs) were decorated with BiVO 4 with distinctive crystallization phases of monoclinic scheelite (m-BiVO 4 ) and tetragonal zircon (t-BiVO 4 ), favorably constructing different molar ratios and concentrations of oxygen vacancies (V o ) for m&t-BiVO 4 /TiO 2 -NTAs heterostructured nanohybrids. Simultaneously, the m&t-BiVO 4 /TiO 2 -NTAs nanocomposites significantly promoted photoelectrochemical (PEC) activity, tested under UV-visible light irradiation, through photocurrent density testing and electrochemical impedance spectra, which were derived from the positive synergistic effect between nanohetero-interfaces and V o defects induced energetic charge transfer (CT). In addition, a proposed self-consistent interfacial CT mechanism and a convincing quantitative dynamic process (i.e., rate constant of CT) for m&t-BiVO 4 /TiO 2 -NTAs nanoheterojunctions are supported by time-resolved photoluminescence and nanosecond time-resolved transient photoluminescence spectra, respectively. Based on the scheme, the m&t-BiVO 4 /TiO 2 -NTAs-10 nanohybrids exhibited a photodegradation rate of 97% toward degradation of methyl orange irradiated by UV-visible light, 1.14- and 1.04-fold that of m&t-BiVO 4 /TiO 2 -NTAs-5 and m&t-BiVO 4 /TiO 2 -NTAs-20, respectively. Furthermore, the m&t-BiVO 4 /TiO 2 -NTAs-10 nanohybrids showed excellent PEC biosensing performance with a detection limit of 2.6 μM and a sensitivity of 960 mA cm -2 M -1 for the detection of glutathione. Additionally, the gas-sensing performance of m&t-BiVO 4 /TiO 2 -NTAs-10 is distinctly superior to that of m&t-BiVO 4 /TiO 2 -NTAs-5 and m&t-BiVO 4 /TiO 2 -NTAs-20 in terms of sensitivity and response speed.