Insights on interfacial charge transfer across MoS2/TiO2-NTAs nanoheterostructures for enhanced photodegradation and biosensing&gas-sensing performance

Novel MoS2 nanobelts (NBs) decorated highly ordered alignment TiO2 nanotubes arrays (TiO2-NTAs) with promoted photoelectrocatalytic (PEC) photodegradation and sensing performance under UV-Visible light irradiation were successfully synthesized via a facile combination of anodization and electrodeposition procedure. Simultaneously, the MoS2/TiO2-NTAs nanohybrids presented a significantly enhanced for PEC activity tests, which were mainly ascribed to the synergistic effect between MoS2 NBs and TiO2-NTAs for the efficient separation of photogenerated carriers induced by the enlarged staggered band offset associated with sulfur vacancies defects. Furthermore, self-consistent interfacial charge transfer mechanism and convincing quantitative dynamic process (i.e. rate constant of charge transfer) for MoS2/TiO2-NTAs type-II nanoheterojunctions mediated with the p-type doping effect are proposed, which were evaluated by nanosecond time-resolved transient photoluminescence (NTRT-PL) and time-resolved photoluminescence (TRPL) spectra, respectively. Following this scheme, the photodegradation rate (η) toward degradation of methyl orange for optimum MoS2/TiO2-NTAs-2 nanocomplex was 96% irradiated by UV-Visible light, which are 1.2 and 1.1 times than that of MoS2/TiO2-NTAs-1 and MoS2/TiO2-NTAs-5, respectively. Furthermore, the PEC biosensing analysis of MoS2/TiO2-NTAs-2 was performed for detecting the glutathione, leading to an excellent detect limit of 1.6 μM and the sensitivity of 930 mA cm-2 M-1. Additionally, the sensitivity of gas-sensing for MoS2/TiO2-NTAs-2 is 3.1, which are 1.3 and 1.1 folds than that of MoS2/TiO2-NTAs with MoS2 deposited times 1 min and 5 min, respectively. It is distinctly manifested that the gas sensing performance of MoS2/TiO2-NTAs-2 toward ammonia gas is superior than that of MoS2/TiO2-NTAs-1 and MoS2/TiO2-NTAs-5 in terms of higher sensitivity degree and faster response speed.