Room-Temperature Optoelectronic Gas Sensor Based on Core–Shell g-C3N4@WO3 Heterocomposites for Efficient Ammonia Detection

The ever-growing modern industry promotes the evolution of gas sensors for environmental monitoring and safety inspection. However, traditional chemiresistive gas sensors still suffer from drawbacks of high power consumption and detection limit, mainly due to the insufficient charge-transfer ability of gas-sensing materials. Here, an optoelectronic gas sensor that can detect ppb-level ammonia at room temperature is constructed based on core-shell g-C₃N₄@WO₃ heterocomposites. The growth of WO₃ nanosheets on graphitic g-C₃N₄ nanosheets was precisely controlled, achieving well-defined g-C₃N₄@WO₃ core-shell architectures. Based on the synergism between light activation and the amplification effect of in situ-formed heterojunctions, the g-C₃N₄@WO₃ sensor exhibits improved sensing characteristics for reliable ammonia detection. As compared with the pristine g-C₃N₄ sensor, the sensor response toward ammonia is enhanced 21 times and the detection limit is reduced from 308 to 108 ppb. This work provides a successful approach for the in situ formation of core-shell g-C₃N₄@WO₃ interfacial composites and offers an easy solution for the rational design of advanced optoelectronic gas sensors.