Abstract
Octahedral anatase particles (OAPs) were modified with silver nanoparticles (NPs) by photodeposition method. The properties of OAPs influenced the properties of silver deposits, and thus the photocatalytic activity of the obtained silver-modified OAPs. Photocatalytic activities were tested under UV and vis irradiation for oxidative decomposition of acetic acid and oxidation of 2-propanol, respectively. The properties of silver-modified OAPs were investigated by XRD, STEM, DRS, XPS and time-resolved microwave conductivity (TRMC) method. It was found that electron traps (ETs) worked as nucleation sites for silver, resulting in formation of smaller silver NPs on smaller OAPs with larger content of ETs. The modification with silver resulted in enhanced photocatalytic activity under both UV and vis irradiation. It was found that larger crystallite size of silver NPs, and thus larger polydispersity of silver deposits resulted in broad and intense plasmon resonance peak causing enhanced visible activity. The correlation between photocatalytic activity and TRMC data, e.g., slower decay of TRMC signal for more active samples, allowed discussion on property-governed photocatalytic activities of silver-modified titania.
Highlights
Energy crisis and environmental pollution have become two serious challenges ahead for human beings
It was found that prolongation of hydrothermal reaction (HT) duration resulted in higher crystallinity, larger crystallite size, lower specific surface area and lower amount of electron traps (ET density), as described in detail in previous papers
It has been expected that the properties of titania should influence the course of silver photodeposition as well as the properties of formed Ag NPs
Summary
Energy crisis and environmental pollution have become two serious challenges ahead for human beings. Modification of titania with NPs of noble metal possessing plasmon resonance feature at visible range of solar spectrum (mainly gold and silver) has been intensively investigated, and those materials. In previous study on OAPs it was found that the preparation conditions had important influence on the physicochemical properties of titania (specific surface area, crystallite size, crystallinity, surface composition) including the morphology (the content of faceted NPs), and on the photocatalytic activity [47,48]. To investigate how the properties of titania influence the modification with Ag, as well as how the resultant properties of Agmodified OAPs influence the photocatalytic activity, OAPs samples varied by properties were prepared by ultrasonication-hydrothermal (US-HT) method and modified with Ag NPs by photodeposition.
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