One-step synthesis of 2D C3N4-tin oxide gas sensors for enhanced acetone vapor detection

Abstract This work proposed a one-step method to fabricate the two-dimensional (2D) heterostructural C 3 N 4 -tin oxide (SnO 2 ) nanocomposites with excellent acetone vapor sensing performance. A facile calcination treatment of melamine and SnCl 2 ·2H 2 O without further processing can obtain the expected C 3 N 4 -SnO 2 sensor. Specially, the SnO 2 nanoparticles directly anchor onto C 3 N 4 layer to construct a heterostructure, giving enhanced sensing properties. Compared with pure SnO 2 the heterostructural C 3 N 4 -SnO 2 Exhibits 22 times enhancement of sensing sensitivity as well as fast response/recovery (7 s/8 s). The limit of detection (LOD) of acetone can be as low as 67 ppb, which is far below the concentration in exhaled breath of a diabetic and predicts a possible for diagnosis of diabetes. Such enhancement can be interpreted as the transformation of electrons from SnO 2 to C 3 N 4 layer to form an asymmetric electronic structure in the electron depletion layer of SnO 2 , for which few electrons can change its resistance significantly. Moreover, the large surface area of C 3 N 4 layer provide vast adsorption sites for target gases. Importantly, SnO 2 and C 3 N 4 are low-cost, easy fabrication and eco-friendly materials, and the synthesis strategy presented here is simple, repeatable and operable, thus can be extended to build other-type metal oxides-based nanocomposites for various applications.