Highly Characteristic Adsorption Based on Single Crystal {001}-TiO₂ Surface Molecular Recognition Promotes Enhanced Oxidation

Abstract

Exploring the adsorption and selective removal mechanism of target pollutants on the catalytic interface is an important research topic in the field of environmental sewage treatment. However, the molecular recognition based on the surface of single crystals is still unclear. Single crystal molecularly imprinted TiO2 (001-MI-TiO2) with a highly exposed {001} plane was prepared by a hydrothermal method to characteristically adsorb and degrade phenol. The kinetics of phenol oxidation on 001-MI-TiO2 was 12.93 times that of polycrystal nonimprinted TiO2. The phenol adsorption quantity of 001-MI-TiO2 was 1.68 times that of the polycrystal molecularly imprinted TiO2 (MI-TiO2). Compared with MI-TiO2, the significantly increased removal of phenol on 001-MI-TiO2 mainly attributed to the enhanced adsorption quantity and better photocatalytic performance. The recognition mechanism of phenol on the 001-MI-TiO2 during the adsorption process was studied using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), which indicated enhanced adsorption of phenol when compared with MI-TiO2. The recognition between the phenol molecule and the imprinted sites mainly relied on the hydrogen bond between the π bond of the benzene ring and the hydroxyl group on the surface of TiO2. Besides, the interferent ATR-FTIR results showed that the single crystal surface can significantly reduce noncharacteristic adsorption, indicating good selectivity for the targets. In addition, the degradation intermediates during the photocatalytic process were further analyzed by in situ infrared technology.

Hydroxyl-group-modified polymeric carbon nitride with the highly selective hydrogenation of nitrobenzene to N-phenylhydroxylamine under visible light

“…As a metal-free, environmentally friendly visible light absorbable photocatalyst, polymeric carbon nitride (PCN) has raised wide concern in photodegradation of pollutants, [17][18][19] reduction of CO 2 , 20,21 H 2 production [22][23][24] and, in particular, organic photosynthesis. [25][26][27][28][29][30][31][32][33] Many works had been reported that the surface modified methods can regulate the catalytic performance of the polymeric carbon nitride, and even control the selectivity of the reaction. For instance, our group has previously reported that the cyano modified PCN can selective control the conversion of benzylamine to imine.…”

Mechanism of Photodegradation of Organic Pollutants in Seawater by TiO2-Based Photocatalysts and Improvement in Their Performance

“…The photodegradation mechanism of organic pollutants in seawater by TiO 2 -based catalysts is discussed here. During the heterogeneous photocatalysis process, the photocatalysts (like TiO 2 ) first adsorb some pollutants to form an interaction with the catalyst surface, before irradiation. , After light excitation, TiO 2 first forms photogenerated holes and electrons. ,, Then, the photogenerated holes directly decompose organic matter on the catalyst surface, or the holes react with adsorbed water and hydroxyl groups to form • OH and degrade organic matter. , These two processes could be considered as surface reactions, as shown in Figures and . In addition, the photogenerated holes and electrons may diffuse into the bulk phase to react with water or oxygen to generate • OH and • O 2– , which further decomposes organic pollutants in the bulk phase of the wastewater.…”

“…During the heterogeneous photocatalysis process, the photocatalysts (like TiO 2 ) first adsorb some pollutants to form an interaction with the catalyst surface, before irradiation. 20,21 After light excitation, TiO 2 first forms photogenerated holes and electrons. 12,13,20 Then, the photogenerated holes directly decompose organic matter on the catalyst surface, or the holes react with adsorbed water and hydroxyl groups to form…”

“…20,21 After light excitation, TiO 2 first forms photogenerated holes and electrons. 12,13,20 Then, the photogenerated holes directly decompose organic matter on the catalyst surface, or the holes react with adsorbed water and hydroxyl groups to form…”

Construction and photocatalytic performance of fluorinated ZnO–TiO2heterostructure composites

“…In order to address the above-mentioned problems, scientic researchers have carried out many explorations, including doping with metal and non-metallic ions, codoping, coupling with semiconductors and exposure of specic crystal planes. [25][26][27][28][29][30][31][32][33][34][35][36] The above ways effectively improve the photocatalytic activity of TiO 2 .…”