Strongly coupled Ag/TiO2 heterojunctions for effective and stable photothermal catalytic reduction of 4-nitrophenol

• Published in: Nano research Vol. 11; no. 1; pp. 126 - 141
• Main Authors: Gu, Ying, Jiao, Yanqing, Zhou, Xiaoguang, Wu, Aiping, Buhe, Bater, Fu, Honggang
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01-01-2018; Springer Nature B.V
• Subjects: Ag/TiO2;催化剂;异质;稳定;AgNO3;一致分布;催化反应;变换效率; Aminophenol; Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Catalysts; Catalytic converters; Chemical synthesis; Chemistry and Materials Science; Condensed Matter Physics; Ethylene glycol; Heating; Heterojunctions; Irradiation; Light; Light irradiation; Materials Science; Nanoparticles; Nanotechnology; Nitrophenol; Photothermal conversion; Research Article; Reuse; Silver; Surface plasmon resonance; Titanium; Titanium dioxide; Ultraviolet radiation; TiO; 4-nitrophenol; Ag; heterojunction; photothermal catalysis
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-017-1612-5

The development of effective catalysts for the catalytic conversion of the harmful nitrophenol （NP） into the useful aminophenol （AP） has received extensive interest. Herein, we report the easy and large-scale synthesis of strongly coupled Ag/TiO2 heterojunctions based on the coordinated action of organic components with a multi-kind metal precursor. The heterojunctions were effective and stable catalysts for the photothermal catalytic reduction of 4-NP to 4-AP. In the synthesis, critic acid, ethylene glycol AgNO3, and tetrabutyl titanate were dissolved and coordinated in water. Under heating, a precursor gel having a uniform distribution of Ag and Ti was gradually formed. Via calcination in air, the Ti precursor was transformed into TiO2, accompanied by the reduction of Ag＋ to Ag nanoparticles. The formation of Ag/TiO2 composites with intimate interface contact benefited from the uniform distribution of different components in the precursor gel. The Ag/TiO2 functioned as an effective catalyst for the reduction of 4-NP, exhibiting higher activity than the many reported Ag-based catalysts. The catalytic reaction over Ag/TiO2 had a small to with good activity and reuse performance. After 10 cycles of reuse, the conversion efficiency exhibited no obvious change. Importantly, the conversion of 4-NP was significantly enhanced under light irradiation provided by a 150-W Xe lamp （the visible light from cutoff have equal function）, but ultraviolet light did not promote the conversion. The conversion time was reduced from 620 to 270 s with light irradiation （15 ~C）. The reaction rate under light irradiation （0.014 s-1） was approximately three times higher than that in the dark at 15 ~C （0.0044 s-1） and even better than that in the dark at 25 ~C （0.01 s-l）. A series of experiments indicated that the light irradiation promoted the conversion of 4-NP because of the localized surface plasmon resonance effect of Ag, which generated hot e- and h~ particles and local heating around the particles via their absorption of the light.