A stable and translucent Bi@Bi 4 Ti 3 O 12 /TiO 2 film was fabricated on conventional glass substrates for the first time. The film exhibited a good photocatalytic performance and efficient self-cleaning capability against organic dyes under full spectral irradiation and visible light irradiation. Bi 4 Ti 3 O 12 /TiO 2 film was first prepared on a glass substrate with colloidal silica as a high temperature binder, followed by implantation of nanoscale Bi in it by an in-situ partially reduction of Bi 4 Ti 3 O 12 to generate Bi@Bi 4 Ti 3 O 12 /TiO 2 films. The improved photocatalytic ability is probably attributed to the surface plasmon resonance of Bi atom as well as the enhanced electron transfer efficiency and synergistic effect of Bi 4 Ti 3 O 12 and TiO 2 . According to trapping experiments, hydroxyl radicals (OH) were active species in the photocatalytic degradation of dyes under full spectral light irradiation and possible photocatalytic mechanism was proposed. The film prepared in this work may well have potential practical applications in many aspects, such as cleansing treatments for high building external decorative panels and also systematic characterization of the film suggests that the in-situ reduction is an effective and simple way to produce nanoscale Bi@Bi 4 Ti 3 O 12 .
Xue Xiao,Qiuhui Zhu,Jiapeng Hu,Yin Shen,Yu Huang,Yuanhao Wang,Chuanyi Wang
Photocatalysis is appealing in removing trace NO, but its efficacy is often deteriorated by H 2 O, which is ubiquitous in environment, and how to resolve this issue and elucidate the underlying mechanisms at the molecular-level are challenging. Herein, we report a full-spectrum Bi/Bi 4 Ti 3 O 12 catalyst modified with Bi-O vacancy associates via a steam-assisted chemical reduction process. The optimized structure demonstrates NO removal efficiency of 75.5 %, four times over its counterpart, Bi 4 Ti 3 O 12 (37.9 %). Based on positron annihilation spectra and theoretical studies, the enhanced activity is induced by Bi-O vacancy associates, which not only optimizes the photogenerated carrier dynamical behaviors but lowers the energy barriers for photocatalytic oxidation of NO. Importantly, the photothermal activity of the optimal sample exhibited a decline from 76.7 % (0 % RH) to 71.2 % (100 % RH), whereas its photoactivity (20°C) demonstrated a more pronounced decrease, dropping from 60.1 % (0 % RH) to 41.2 % (100 % RH). Therefore, humidity-resistant performance over the optimal sample is attributed to photothermal effect induced by in-situ precipitated Bi and multiple defects. Furthermore, the results of adsorption and desorption behavior of H 2 O and in situ DRIFTS suggest the photothermal-assisted desorption of surface-bound H 2 O can suppress the interactions of H 2 O and stable bidentate nitrate ( bi -NO 3 ⁻) by hydrogen bonds to generate monodentate nitrate ( m -NO 3 ⁻), thereby hindering the photodecomposition of m -NO 3 ⁻ to NO/NO 2 . This work elucidates the significance of photothermal effect in developing efficient photocatalyst for atmospheric NO purification in humid conditions.
Meidan Que,Jiaojiao Zheng,Xiangwei Bai,Ruochen Shi,Peihong Ma,Xun Sun,Jun Xu,Yao Wang
Bi 4 Ti 3 O 12 is a bismuth-based photocatalyst that belongs to the Aurivillius family of compounds, and it has garnered widespread attention in the field of photocatalysis due to its unique layered structure. However, it is dominated by single-electron-transfer during the reaction, which hinders the deep reduction of CO 2 to CH 4 and limits catalytic performance. In this work, Bi 4 Ti 3 O 12 was modified through the in-situ loading of Bi 0 metallic nanoparticles and Yb 3+ doped. Experimental results confirm that the Bi/Bi 3.99 Yb 0.01 Ti 3 O 12 exhibits superior photocatalytic activity, with CO and CH 4 production rates of 5.70 μmol g −1 h −1 and 5.32 μmol g −1 h −1 , respectively. Mechanistic investigations reveal that the Ohmic contact between Bi 0 and Bi 4 Ti 3 O 12 improves electron transport efficiency. Meanwhile, the constructed O 2 p -Yb 4 f -Yb 5 d -Ti 3 d electron-transfer bridge promotes multi-electron reaction kinetics and suppresses photogenerated carrier recombination, fundamentally improving the selectivity of CO 2 methanation. This study clarifies the electronic modulation mechanism induced by rare-earth doped, providing a feasible strategy and technical reference for the design of high-performance photocatalysts toward efficient CO 2 methanation.
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