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

Nitric oxide (NO x, including NO and NO 2 ) is one of the most dangerous environmental toxins and pollutants, which mainly originates from vehicle exhaust and industrial emission. The development of sensitive NO x gas sensors is quite urgent for human health and the environment. Up to now, it still remains a great challenge to develop a NO x gas sensor, which can satisfy multiple application demands for sensing performance (such as high response, low detection temperature, and limit). In this work, ultrathin In 2 O 3 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 In 2 O 3 ultrathin nanosheets exhibit an ultrahigh response ( R g / R a = 213) and a short response time ( ca . 4 s) toward 10 ppm NO x, and a quite low detection limit (10 ppb NO x ) 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.