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Bi Cocatalyst/Bi2MoO6 Microspheres Nanohybrid with SPR-Promoted Visible-Light Photocatalysis

Zhao, Zaiwang, Zhang, Wendong, Sun, Yanjuan, Yu, Jiayan, Zhang, Yuxin, Wang, Hong, Dong, Fan, Wu, Zhongbiao
The Journal of Physical Chemistry C 2016 v.120 no.22 pp. 11889-11898
X-ray diffraction, X-ray photoelectron spectroscopy, absorption, air, bismuth, carbon nitride, free radicals, glucose, hydroxyl radicals, ions, irradiation, microparticles, molybdenum, nanohybrids, nanoparticles, nitric oxide, optical properties, oxidation, photocatalysis, photocatalysts, scanning electron microscopy, surface plasmon resonance, titanium dioxide, transmission electron microscopy, ultraviolet-visible spectroscopy
To develop efficient visible light driven photocatalysts for air purification, we constructed a novel semimetal–semiconductor Bi–Bi₂MoO₆ (Bi–Mo) nanohybrid via the in situ deposition of Bi nanoparticles on the surface of Bi₂MoO₆ microspheres. In this strategy, the Bi³⁺ ions were in situ reduced to metallic Bi particles by glucose during in hydrothermal process. The XRD, XPS, SEM, TEM, UV–vis, DRS, PL spectra, and surface photovoltage were employed to explore the structural and optical properties. The as-synthesized Bi–Bi₂MoO₆ nanohybrid was applied in photocatalytic removal of NO in air. The results indicated that the amount of reductive glucose not only exerted a pivotal effect on the morphological structure but also affected the photocatalytic capability of the Bi–Bi₂MoO₆ nanohybrid. The optimized Bi–Mo-50 hybrids exhibited exceptionally high visible-light photocatalytic performance with a NO removal ratio up to 68.1%, far outperforming other decent photocatalysts, like BiOBr (21.3%), C-doped TiO₂ (21.8%), N-doped TiO₂ (36.5%), N-doped (BiO)₂CO₃ (43.5%), and g-C₃N₄ (32.7%). This drastically enhanced photocatalytic capability was ascribed to the cocontributions of the enhanced light absorption and the improved separation efficiency of the charge carriers owing to the surface plasmon resonance (SPR) induced by Bi metal. The Bi metal performs as noble metal-like cocatalyst for promoting the photocatalysis efficiency. Based on the DMPO-ESR spin trapping, the active species generated from Bi/Bi₂MoO₆ under visible light were •OH radicals. The Bi/Bi₂MoO₆ produced more •OH radicals contributing to strengthen oxidation ability in comparison with that of the pristine Bi₂MoO₆. In addition, this advanced Bi/Bi₂MoO₆ nanohybrid also exhibited high photochemical stability under repeated irradiation. This work demonstrated the feasibility of utilizing economical Bi element as a cocatalyst to substitute the precious noble metals to advance the photocatalysis efficiency.