Controlled Ag-TiO2 heterojunction obtained by combining physical vapor deposition and bifunctional surface modifiers

Abstract

A controlled physical method without any solvent was used to grow Ag nanoparticles on TiO2 by use of mercaptoacetic acid as a bifunctional surface modifier. The fabricated Ag-TiO2 tight heterojunction was proposed as an innovative photocatalytic material. The particle size, chemical nature, morphology, and chemical bonding between mercaptoacetic acid, Ag, and TiO2 were characterized by UV–vis absorption spectroscopy, powder X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The photocatalytic activity of TiO2 combined with the excellent electron acceptor abilities and visible light absorption of small spherical Ag nanoparticles resulted in efficient photoinduced degradation of a cationic organic pollutant (methylene blue) under UV–vis light. The nanocatalyst material obtained with a sputter time of 30 s under simulated sunlight results in almost complete degradation (97%) of methylene blue after 120 min. The particle size, tight attachment to TiO2, and distribution of Ag nanoparticles were controlled for the first time through a physical method by use of controlled chemical bonding to bifunctional surface modifiers and an appropriate sputter deposition time.