Xiuquan Gu

Enhanced visible-light photocatalytic activity and stability by incorporating a small amount of MoS2 into Ag3PO4 microcrystals

A small amount of multilayer MoS2 (ML-MoS2) nanosheets (NSs) were incorporated during the preparation process of Ag3PO4 microparticles, a high-efficient visible-light photocatalyst. Further, the effect of MoS2 contents was investigated on the structure, morphology and photocatalytic (PC) performance of the hybrids. It was demonstrated that the PC activity of hybrids got improved after incorporating trace amount of MoS2 NSs, and the optimized molar ratio was 1:40. Meanwhile, the PC recyclability was also found to be enhanced a lot after forming a hybrid. Thus, it was speculated that a Z-scheme system might be formed at the interfaces of Ag3PO4/MoS2 hybrids, which might be responsible for the enhanced PC activity and recyclability.

Surface engineering of perovskite films for efficient solar cells

It is critical to prepare smooth and dense perovskite films for the fabrication of high efficiency perovskite solar cells. However, solution casting process often results in films with pinhole formation and incomplete surface coverage. Herein, we demonstrate a fast and efficient vacuum deposition method to optimize the surface morphology of solution-based perovskite films. The obtained planar devices exhibit an average power conversion efficiency (PCE) of 13.42% with a standard deviation of ±2.15% and best efficiency of 15.57%. Furthermore, the devices also show excellent stability of over 30 days with a slight degradation <9% when stored under ambient conditions. We also investigated the effect of vacuum deposition thickness on the electron transportation and overall performance of the devices. This work provides a versatile approach to prepare high-quality perovskite films and paves a way for high-performance and stable perovskite photovoltaic devices.

Enhanced visible-light photoelectrochemical activity of TiO 2 nanorod arrays decorated by Sb 2 S 3 particles

Single-crystal TiO2 nanorod arrays (NRAs) were synthesized successfully onto transparent conducting substrates through a facile hydrothermal route for photo-electrochemical (PEC) water-splitting. Further, the ordered TiO2 NRAs were treated by SbCl3 solution for preparing a layer of Sb2S3 and enhancing their PEC activity. A series of methods were employed to compare and analyze the differences between the TiO2 NRA samples with/without Sb2S3 decoration. It was demonstrated that the PEC performance were enhanced significantly after being treated with SbCl3 aqueous solution (precursor) under a hydrothermal environment. Compared to pure TiO2 NRAs, the sample that decorated with Sb2S3 showed a more positive flat-band level as well as a higher donor density (i.e. electron density). Thus, it suggested that the enhanced PEC performance after Sb2S3 modification might be attributed to the widening of spectral response as well as the improvement of charge transfer / transport occurring at the solid/liquid interfaces.

Influence of Annealing Ambient on the Photoelectric and Photoelectrochemical Properties of TiO2 Nanorod Arrays

Ordered TiO2 nanorod arrays (NRAs) have been synthesized on transparent conducting F-doped SnO2 (FTO) substrates via a facile hydrothermal method for dye-sensitized solar cells (DSSCs). Annealing in air at 500°C resulted in a large enhancement of DSSC performance, while the performance was much decreased after annealing in the reducing ambient (Ar or vacuum). This was ascribed to a lowering of the interfacial charge separation or injection. Moreover, it was also found that the photoelectrochemical activity of TiO2 NRA was enhanced after annealing in Ar or vacuum, which was totally opposite to the variation of DSSC performance, and was ascribed to the enhancements of both interface charge transfer and visible-light absorption (as had been confirmed by the color change).