The photocatalytic activity of SiO2-TiO2/graphite and its composite with silver and silver oxide

Abstract

This research study the mixed semiconductor of SiO2-TiO 2 which was immobilized on graphite substrate and also studies the effect of surface modification on its mixed semiconductor. The surface modification was car-ried out by electrode position of Ag from 0.4 M of AgNO3 solution at various applied current. The electrode position was conducted for 30 minutes at 0.004; 0.008; 0.010; 0.012 and 0.014 A. In the electrode position cell, SiO2-TiO2/Graphite was used as cathode and a graphite rod was used as anode. The weight of deposited Ag was analyzed gravimetrically. The current efficiency of electrode position was calculated by comparing its experimental weight to its theoretical weight founded from calculation using Faraday's equation for elec-trolytic cell. Meanwhile, the photo electrochemical testing was carried out to investigate the efficiency of in-duced photon to current conversion; it was measured as %IPCE (% Induced Photon to Current Efficiency). The crystallinity and crystal structure of the prepared materials were analyzed by X-ray diffraction and their surface morphology was analyzed by Scanning Electron Microscope (SEM). This research found that silver was deposited as silver metal, Ag and as silver oxide, AgO. The electrode position efficiency at applied current of 0.014 A is 92.30 % with diameter of cluster is 7 - 11.9 mm. It is founded that Ag and AgO deposi-tion enhanced the efficiency of photon conversion into current up to 89.92 %. The optimum %IPCE value is at 28.6 % of Ag content. Ag-SiO2-TiO 2/G has higher photo conversion than Ag-TiO2/G, shown by the %IPCE value at 300 nm is 83.25 % higher than Ag-TiO2/G. It indicates the significant role of silica network in photo excitation mechanisms in the composite material. © 2014 BCREC UNDIP.