Xueting Zhao,Junhao Ma,Jindan Zha,Kuisui Huang,Chenghui Chai,Zhaoyi Yin,Zhiguo Song,Jianbei Qiu,Yongjin Li
Traditional inorganic photoreversible color-switching materials (PCSMs) usually exhibit slow color switching and single color switching characteristics, which severely restrict their use in information storage, anti-counterfeiting, and other applications. Herein, we report a fast photoresponsive color-switching inorganic PCSM based on oxygen-vacancy (OV) Bi3O4Br:Yb3+,Er3+ (BYE-OV) nanosheets. The BYE-OV nanosheets demonstrated considerable photoreduction activity and effective charge carrier separation when exposed to ultraviolet (UV) light, resulting in a rapid change in color from light yellow to dark brown. Moreover, under 980-nm excitation, the green and red emissions of the BYE-OV nanosheets were considerably enhanced, being 9.6 and 8.8 times higher than those of the BYE nanosheets, respectively. Additionally, BYE-OV nanosheets were combined with an agarose hydrogel to produce BYE-OV/agarose nanocomposite films, which exhibited excellent photoreversible color switching and upconversion (UC) luminescence. This research provides new insights into the development of innovative inorganic PCSMs, thereby considerably broadening their potential applications.
The efficient utilization of near-infrared (NIR) light is an important challenge to extend the spectral response range of photocatalysts. Here, the NIR photocatalytic performance of Bi 3 O 4 Br nanosheets was significantly enhanced by a rare earth ion doping strategy that synergistically utilizes the dual mechanism of photon conversion and energy band modulation. Under 980 nm excitation, the Bi 3 O 4 Br:Er 3 + nanosheets exhibit near-single-band green upconversion (UC) emission and are reabsorbed by Bi 3 O 4 Br. Combined with DFT density of states calculations, it is shown that the band gap of the material has been lowered and the carrier transport paths have been optimized by the energy-band structural tuning. In the NIR photocatalytic degradation experiment of bisphenol A, Bi 3 O 4 Br was not degraded, and Bi 3 O 4 Br:Er 3+ showed better performance, which was 2.27 times higher than that of Bi 3 O 4 Br:Yb 3+ , Er 3+ . ESR testing and capture experiments indicate that under NIR light irradiation, •OH and e − are the primary active species in the photocatalytic reaction process. This work provides new design ideas for the development of efficient NIR photocatalytic materials.
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