Selection of semiconducting metal oxides for light-activated gas sensors at low temperature

Light activation is a promising approach for lowering the power consumption and increasing the selectivity of chemoresistive gas sensors based on semiconducting metal oxides. In this study, different aspects of commonly used materials are investigated, compared, and evaluated for their application as gas sensors. Their ability to detect CO and NO $_2^{}$ at low temperature (70 $_{}^{\circ }$ C) highly depends on the wavelength used for activation. The reaction with atmospheric oxygen is also highly affected by illumination, as adsorption, desorption, and free charge carrier concentration are influenced by light. For this reaction, the relationship between band gap and photon energy becomes apparent, which is not the case for the detection of analyte molecules. Investigations on the long-term stability indicate that only certain combinations of wavelengths and materials are suitable for prolonged and stable operation.