Pt-decorated ZnFe2O4 sensors prepared via a facile impregnation method free of reductants and surfactants for conductometric acetone sensing

Abstract

Noble metals have been widely reported to improve sensing properties. However, conventional methods of preparing noble metal-decorated metal oxide sensors usually involve the use of multiple reductants and surfactants, as well as complex equipment and procedures, and most importantly, waste noble metal sources. In this study, we develop a novel modified impregnation method, which is a green, energy-saving, fast, convenient technique for preparing Pt-decorated ZnFe2O4 gas sensors. This method consists only of mixing ZnFe2O4 powder into a H2PtCl6 solution and then fabricating sensors by a general procedure, without the use of additional reagents or further treatment. Detailed structural and chemical analyses revealed that over 88% of Pt element was uniformly dispersed on the surface of ZnFe2O4. The average activation energy decreased by 51% after Pt was decorated onto the surface of ZnFe2O4, resulting in a shorter response time. As expected, the thus prepared Pt-decorated ZnFe2O4 sensors are superior to pristine commercial ZnFe2O4 in terms of better sensing properties, a higher response, and a lower optimal temperature. The proposed reductant-free impregnation method was demonstrated to provide noble-metal-decorated metal oxides successfully, easily, quickly, and economically.