To avoid carcinogenicity, formaldehyde gas, currently being only detected at higher operating temperatures, should be selectively detected in time with ppb concentration sensitivity in a room-temperature indoor environment. This is achieved in this work through introducing oxygen vacancies and Pt clusters on the surface of In2O3 to reduce the optimal operating temperature from 120 to 40 °C. Previous studies have shown that only water participates in the competitive adsorption on the sensor surface. Here, we experimentally confirm that the adsorbed water on the fabricated sensor surface is consumed via a chemical reaction due to the strong interaction between the oxygen vacancies and Pt clusters. Therefore, the long-term stability of formaldehyde gas detection is improved. The results of theoretical calculations in this work reveal that the excellent formaldehyde gas detection of Pt/In2O3-x originates from the electron enrichment due to the surface oxygen vacancies and the molecular adsorption and activation ability of Pt clusters on the surface. The developed Pt/In2O3-x sensor has potential use in the ultraefficient, low-temperature, highly sensitive, and stable detection of indoor formaldehyde at an operating temperature as low as room temperature.
Keywords: formaldehyde; indium sesquioxide; oxygen vacancy; platinum cluster; sensor.