Surface free radicals activated CoP/MoS2 sensors through electrocatalytic water splitting for enhanced NO2 sensing at room temperatures

Exploration of novel strategies to activate the gas sensing performance for flexible and wearable applications is always a hot topic in gas sensing field. Herein, CoP nanoparticle decorated MoS2 nanosheets are developed for flexible and highly sensitive NO2 detections through a surface free radical activation strategy. Amorphous CoP are confirmed to be successfully loaded on MoS2 surface. The as-fabricated CM-2 flexible sensors (CoP/MoS2 with addition of 58.2 mg Co(NO)3·6H2O in the synthesis) realize enhanced sensing performance to NO2 gas at room temperatures (61 %@100 ppm). Besides, a rapid sensing transience (15 s) and low limit of detection (30 ppb) are also achieved. The higher adsorption capacity of CM-2 and the completely desorption of NO2 gas on the sensor surface are also confirmed by TPD and in-situ DRIFTs measurements. For the sensing mechanism, the free radicals facilitate the chemical adsorption of NO2 gas as confirmed by EPR spectra and DFT calculations, which significantly enhance the sensing behavior. Finally, an intelligent sensing system of smart bracelet for NO2 sensing is incorporated with the flexible sensors. This study paves the way for exploration of novel strategies to improve the sensing performance for flexible and wearable applications.