Ultrathin In2O3 Nanosheets with Uniform Mesopores for Highly Sensitive Nitric Oxide Detection.

Nitric oxide (NOx, including NO and NO2) is one of the most dangerous environmental toxins and pollutants, which mainly originates from vehicle exhaust and industrial emission. The development of sensitive NOx gas sensors is quite urgent for human health and the environment. Up to now, it still remains a great challenge to develop a NOx gas sensor, which can satisfy multiple application demands for sensing performance (such as high response, low detection temperature, and limit). In this work, ultrathin In2O3 nanosheets with uniform mesopores were successfully synthesized through a facile two-step synthetic method. This is a success due to not only the formation of two-dimensional (2D) nanosheets with an ultrathin thickness of 3.7 nm based on a nonlayered compound but also the template-free construction of uniform mesopores in ultrathin nanosheets. The sensors based on the as-obtained mesoporous In2O3 ultrathin nanosheets exhibit an ultrahigh response (Rg/Ra = 213) and a short response time (ca. 4 s) toward 10 ppm NOx, and a quite low detection limit (10 ppb NOx) under a relatively low operating temperature (120 °C), which well satisfies multiple application demands. The excellent sensing performance should be mainly attributed to the unique structural advantages of mesopores and 2D ultrathin nanosheets.