Active Polymer-Templated Porous Metal Oxide Nanospheres with Tailored Single-Atom Modification for Olfactory...

Controllable synthesis of monodisperse porous metal oxide semiconductor (MOS) nanospheres with uniform size and a tailored chemical environment is highly desired in the compatible manufacturing of high-performance nanodevices. However, the lack of an effective synthesis method has been a crucial challenge due to the uncontrollable hydrolysis rate of precursors and insufficient coassembly driving force. Herein, an active colloidal polymer-directing method is proposed for the facile synthesis of uniform functionalized mesoporous MOS nanospheres, such as mesoporous SnO₂ nanospheres with different single-atom modifications (SA/mSnO₂). This synthesis method features the utilization of single-atom-modified mesoporous polydopamine nanospheres as the intermediate, whose phenolic hydroxyl and imine groups enable the formation of the SnO₂ skeleton and stabilization of SA, respectively. A library of stable gas-sensing inks is prepared based on the obtained SA/mSnO₂ nanospheres, enabling wafer-scale fabrication of sensing layers on microelectromechanical systems chips through high-speed printing. These as-fabricated SA/mSnO₂ sensors exhibit tailored selectivity due to different single-atom modifications, high sensitivity (5.6 times higher than that of commercial sensors), and excellent device-to-device consistency. Furthermore, by integrating different SA/mSnO₂ nanodevices into sensor arrays, an advanced intelligent olfactory system is produced and further integrated into an automated guided vehicle, enabling the autonomous identification and transport of low-concentration leaked chemicals.