The issue of environmental pollution has got worse due to the quick expansion of manufacturing, industry, and human society. Among different pollutants, the emission impact of volatile organic compounds (VOCs) has been steadily expanding, posing a significant challenge to human health. Gas sensors are devices that convert gas concentration from chemical to electrical signals and play a central role in real-time gas detection system. According to previous studies, ZnO exhibited high response, excellent selectivity, and less recovery time in identifying of dangerous and flammable gases. However, the gas-sensing performance of ZnO sensors remains suboptimal under industrial conditions. To enhance their performance, strategies such as metal-ion doping, noble metal activation, and heterojunction formation with other semiconductors are commonly employed.

Chen et al. prepared ZnO nanoflakes by a hydrothermal method, which offers advantages including simple operation, excellent crystallinity, and controllable morphology without requiring templates or surfactants. Noble metal (Au, Pt, and Pd) nanoparticles were subsequently loaded onto the ZnO nanoflakes via an ultraviolet (UV) reduction method. Compared to conventional chemical reduction or impregnation techniques, UV-assisted reduction proceeds under mild conditions without the need for additional reducing agents, thereby minimizing surface contamination and enabling the formation of small, uniformly dispersed metal nanoparticles. The combination of hydrothermal synthesis and UV reduction provides a facile, green, and scalable route for the fabrication of noble metal/ZnO heterostructures with intimate interfacial contact. Such materials were then tested and analyzed to investigate their sensing performance for application to VOCs, and the Au/ZnO material showed superior response to isopropanol as compared to the unmodified ZnO nanoflakes. Moreover, the gas-sensing performance to hydrogen was also researched, and potential gas-sensing mechanisms were presented. This work was recently reported by Frontiers of Materials Science.
DOI：10.1007/s11706-026-0775-y