Highly selective NO2 sensor based on Au/SnS2 nano-heterostructures via visible-light modulation

The efficient monitoring of toxic nitrogen dioxide (NO2) reveals a great practical significance in terms of environmental protection and human health. Tin disulfide (SnS2) has recently presented bright application prospects for the NO2 detection owing to its unique physiochemical properties. Unfortunately, the pristine SnS2-based gas sensor suffers from inferior selectivity to NO2 since the emerging cross-response over interfering gases (especially to NH3) at room temperature. Herein, a room-temperature-operated gas-sensitive device based on Au nanoparticles decorated SnS2 nanosheet was proposed for the highly selective detection towards NO2 by exploiting visible-light modulation. Benefited from the electronic sensitization and chemical sensitization of Au nanoparticles, the Au/SnS2 gas sensor presented a visibly enhanced response toward 1 ppm NO2 compared with pristine SnS2 gas sensor, while its selectivity to NO2 over NH3 only increased by 35%. Further, through effectively modulating the adsorption and reaction behavior of gas molecules by introducing visible-light excitation, the Au/SnS2 gas sensor manifested an excellent selectivity with 130% gain in detecting 1 ppm NO2 at room temperature, endowed the robust repeatability and reliable long-term stability. This work thus demonstrates that the visible-light modulation can serve as a promising technique for exploiting highly selective gas-sensitive devices operating at room temperature.