CoP decorated SnS2 nanosheets with synergistic electronic and electrocatalysis sensitization for enhanced room temperature NO2 sensing

Abstract

Due to the metal-like property and high catalytic activity, CoP material has been regarded as a potential noble metal alternative in gas sensing area. Herein, CoP decorated SnS2 nanosheets were successfully synthesized via an ultrasonic assisted physical combination method. Structure characterizations indicated the ultrasmall sizes and uniform distributions of CoP nanoparticles on SnS2 nanosheet surface. Gas sensing results showed that the SP-3 sensors (mass ratio: CoP/SnS2 =1:3) possessed much higher sensing response (80 %@10 ppm) to NO2 gas at room temperature (RT, 25 °C) than pristine SnS2 (nearly no response) and 5 % Pt modified SnS2 (57.4 %@10 ppm), indicating a better sensitization effect of CoP than Pt nanoparticles. Arrhenius equation fitting results showed that CoP mainly enhanced the NO2 sensing behavior by electronic sensitization via constructing heterojunctions with SnS2. Moreover, the NO2 sensing response of SP-3 sensors also increased with adding trace water molecules, contradict to the response curve versus increasing relative humidity, due to the dynamic equilibrium between electrocatalytic water splitting facilitated surface NO2 adsorptions and over-adsorption of water vapors hindered NO2 adsorptions. This work highlights the important role of CoP in gas sensing, which will also promote the exploration and understanding of novel materials to replace noble metal.