In-place synthesis of Pt-modified brookite TiO2 micrometre-sized sensing elements via wet oxidation of Ti/Pt/Ti films on glass

Abstract

In-place synthesis of Pt-modified brookite TiO2 micrometre-sized sensing elements via wet oxidation of Ti/Pt/Ti multilayers on glass Pt-modified anatase polymorph of TiO2 is one of the most widely reported oxides used for sensing. In contrast, there is much fewer published work on brookite polymorph of TiO2 (TiO2(B)) because of its smaller stability window. Here, we demonstrate a one-step process to synthesize in-place micrometer-sized Pt-modified TiO2(B) sensing elements. Ti/Pt/Ti multilayer films sputtered on glass substrates were selectively oxidized in aqueous hydrogen peroxide to form a gel. Upon thermal annealing gel films transformed into TiO2(B). Stability of TiO2(B) is attributed to diffusion of sodium ions from glass. Pt-TiO2(B) gas sensors exhibited shorter response time and higher current increase compared to similar devices utilizing anatase TiO2 (TiO2(A)). Sensor response of up to 6 × 105 was achieved in 4000 ppm hydrogen gas.