Salicylate-Assisted Surfactant-Directed Assembly Synthesis of Uniform Mesoporous ZnO Nanospheres for Gas Sensing Applications

Abstract

Mesoporous zinc-based nanomaterials exhibit considerable potential across a spectrum of applications, yet their controlled synthesis remains challenging due to the rapid hydrolysis and condensation kinetics of Zn²⁺ ions. Herein, we report a facile surfactant-directed synthesis strategy for the controllable synthesis of monodisperse mesoporous Zn(OH)₂ nanospheres and they can be readily converted into semiconducting mesoporous ZnO (denoted mZnO) nanospheres via calcination. In this synthesis, by employing sodium salicylate (NaSal) as a multifunctional modulator, we regulate micelle organization and zinc precursor diffusion, overcoming the inherent kinetic limitations of Zn²⁺. The resulting crystalline mZnO can serve as an ideal host for loading ultrasmall Pt nanoclusters to produce Pt/mZnO composite nanospheres with abundant metal–metal oxide interfaces. Using Pt/mZnO nanospheres as the sensitive materials, gas sensors were fabricated on micro-electromechanical systems (MEMS) devices, which display an exceptional performance in the detection of low-concentration acetone vapor. The gas sensor exhibited high response (4.9 toward 1 ppm acetone), low detection limit (170 ppb), excellent selectivity, and good long-term stability. In situ spectroscopy characterization results reveal that, during the gas-sensing process, the reaction pathway involves catalytic oxidation of acetone over Pt/mZnO nanospheres via intermediate carboxylates. This work offers a generalized approach for designing functional mesoporous metal oxides with enhanced interfacial activity for advanced sensing and catalytic applications.

Keywords

acetone / core-shell nanostructures / gas sensors / mesoporous materials / mesoporous zinc oxide / salicylate-assisted assembly

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