Low-temperature methane (CH4) gas sensors with high performance have garnered substantial interest due to their potential to reliably monitor CH4 and achieve intrinsic safety. In this work, we explored strategies that combine photo-activation with bimetallic decoration. ZnO, Au/ZnO, Ag/ZnO and bimetallic AuAg/ZnO microspheres were synthesized to evaluate their CH4 sensing capabilities and were characterized using various techniques. The synthesized samples exhibited hollow structures and favourable optical properties. Their sensing performance was assessed at room temperature under 365 nm ultraviolet (UV) illumination. Among these, the AuAg/ZnO microspheres demonstrated superior CH4 sensing performance, characterized by low detection temperature (room temperature), a high-response value (62.61 to 5000 ppm CH4) and a rapid response time (5 s). Furthermore, the response of AuAg/ZnO exceeded that of Au/ZnO (42.29), Ag/ZnO (36.37) and pure ZnO (12.52), being five times higher than that of pure ZnO. The enhanced gas-sensing performance can likely be attributed to the UV light and the synergistic effects of the bimetallic AuAg. This study provides insights into the development of high-performance, room-temperature CH4 sensors.
