Chemical composition, microstructure, bandgap energy and electrocatalytic activities of TiO2 and Ag-doped TiO2 powder synthesized by solution combustion technique

Abstract

Numerous attempts have been made to improve photocatalytic performances of TiO2 and metal-doped TiO2, while scarcer studies report their electrocatalytic activities and potential application as electrochemical sensors. Electrochemical performances of TiO2 are influenced by doping, which consequently affects chemical composition, microstructure, and bandgap energy. This study, hence, aimed at investigating effects of Ag concentration on TiO2 properties and the possible use in nitrite detection. TiO2 and TiO2 doped with 2.5, 5 and 10 mol% Ag powders were synthesized by solution combustion technique, compositionally and microstructurally examined, as well as tested for their bandgap energy and electrocatalytic activities. Experimental results revealed anatase to rutile transformation (ART) in the Ag-doped TiO2 as well as formation of silver oxide. The powders consisted of nano-crystallites, which agglomerated into clusters with average sizes ranging from 58 to 98 nm. Values of bandgap energy were measured to be between 3.04 and 3.34 eV. Cyclic voltammetry measurement of the powders in nitrite solution indicated that oxidation reactions occurred at voltages closed to 0.4 V. The maximum and the minimum peak current of 0.257 mA and 0.0487 mA were observed in the TiO2 powders doped with 5 and 10 mol% Ag, respectively. Electrocatalytic activities of the powders are discussed with respect to chemical composition, microstructure, and bandgap energy.