Porosity and functionality: A study on interdependence

Abstract

The catalytic activity of a material had been dependent on the nature of the matrix.To address this issue, a detailed study was aimed. TiO 2 nanoparticles were fabricated with an unusual anatase crystal phase and an interesting porous morphology. The development of porosity in TiO 2 was skillfully achieved by using hexamine during the synthesis, followed by its selective removal by calcination at an optimum temperature. The route was found to be template-free, green and thoroughly reproducible.Surface of the as prepared TiO 2 was modified with oleic acid (OA) expecting an interaction between Lewis acidic TiO 2 and electron-rich OA. This modification enabled adhesion of Ag nanoparticles on TiO 2 surface, because OA had already been reported as an effective capping agent for Ag nanoparticles. A comparison was made between the photocatalytic activities of TiO 2 and TiO 2 -Ag nanocomposites. This was further compared with commercial variety of TiO 2 . A very interesting trend was observed establishing that porous morphology of the nanoparticles could boost photocatalytic activities toward dye degradation in water medium. All the samples were systematically characterized by Fourier Transform Infrared Spectroscopy, X-ray diffraction, XPS, Brunauer-Emmett-Teller, and Transmission Electron Microscopy.anatase phase, photocatalysis, porous morphology, TiO 2 nanoparticles, TiO 2 -ag nanocomposite | INTRODUCTIONWater pollution, because of several anthropogenic activities, is a serious threat and a number of contemporary researchers are seriously engaged to find easy and reliable routes to degrade toxic organic compounds of contaminant water into H 2 O, CO 2 , and other nonhazardous inorganic species. 1 Photocatalysis with semiconductor oxide-based materials has proved itself to be an effective solution in this respect. A number of successful studies 2,3 on photocatalysis by TiO 2 have definitely dragged special attention to this semiconductor oxide. In fact, apart from photocatalysis, TiO 2 has been used effectively in gas sensing, 4,5 catalysis for organic reactions, 6,7 biosensing, 8,9 drug delivery, 10,11 solar cells, 12,13 and electronics nanodevices. 14,15 The extensive applications of TiO 2 in various fields as compared to other oxides stem because of its chemical stabilization, excellent biocompatibility, non-toxic nature, and inexpensiveness. 16,17 TiO 2 exhibits different phases, and phase-change can be initiated by heating: metastable anatase phase transforms to brookite phase that in turn changes to stable rutile phase. 18 But anatase phase of TiO 2 with intrinsic band gap of $3.2 eV 19 is found to be highly active photocatalyst in the presence of UV-Vis illumination as compared to rutile and brookite phases of TiO 2 . [19][20][21][22] Therefore, in the recent years, the researchers have focused on the challenging synthesis of pure anatase TiO 2 nanocrystals for photocatalytic applications. Photocatalysis proceeds with the formation of photo excited electrons and holes, but the photocatalytic performance of TiO 2 ...