Au-functionalized MoO3 nanoribbons towards rapid and selective formaldehyde gas sensing at room temperature

The detection of indoor formaldehyde concentration attracted great attention owing to its serious harm to human bodies. Traditional semiconductor formaldehyde sensors are still suffering from high working temperature and slow response and recovery performance. In this work, a room-temperature semiconductor formaldehyde gas sensor with fast response and high selectivity were developed by exploiting the synergistic effect of Au deco-ration on MoO3 nanoribbons. The metallic Au nanocrystals with size lower than 10 nm were prepared by a chemical reduction method and uniformly distributed on the surface of the [1 0 0] -oriented orthorhombic MoO3 nanoribbons after the surface decoration. The results show that the surface decoration by Au nanoparticles could greatly fasten the response and recovery speed of the sensors at room temperature. Under an optimal compo-sition with Au/Mo atomic ratio of 0.10%, the response and recovery time towards 100 ppm HCHO could be decreased to 4.5 and 3 s. The sample also exhibited high sensitivity and low limit of detection of 1 ppm. Meanwhile, the sensor exhibited highly selective HCHO response with 1-2 magnitude higher sensor response against toluene, ethanal, methanol and acetone. The performance enhancement should be attributed to syner-gistic effect induced by the surface Au decoration, which not only serves as the catalysts improving the gas adsorption and desorption efficiency, but also introduced additional contribution to the formaldehyde response by forming the metal-semiconductor interface states.