A Straightforward Solvent‐Pair‐Enabled Multicomponent Coassembly Approach toward Noble‐Metal‐Nanoparticle‐Decorated Mesoporous Tungsten Oxide for Trace Ammonia Sensing

Abstract

The straightforward synthesis of noble‐metal‐nanoparticle‐decorated ordered mesoporous transition metal oxides remains a great challenge due to the difficulty of balancing the interactions between precursors and templates. Herein, a solvent‐pair‐enabled multicomponent coassembly (SPEMC) strategy is developed for straightforward synthesis of noble‐metal‐nanoparticle‐decorated nitrogen‐doped ordered mesoporous tungsten oxide (abbreviated as NM/N‐mWO3, NM = Pt, Rh, Pd). The amphiphilic poly(ethylene oxide)‐block‐polystyrene (PEO‐b‐PS) copolymers coassemble with ammonium metatungstate (AMT) clusters and different kinds of hydrophilic noble metal precursors without phase separation. SPEMC synthesis requires no direct interaction between PEO‐b‐PS and AMT, thus the assembly equilibriums between noble metal precursors and PEO‐b‐PS can be readily controlled. The obtained NM/N‐mWO3 nanocomposites possess ordered mesopores, abundant oxygen vacancies, and metal–metal oxide interfaces. As a result, the Pt/N‐mWO3 sensors exhibit superior ammonia sensing performances with high sensitivity, an ultralow limit of detection (51.2 ppb), good selectivity, and long‐term stability. Spectroscopic analysis reveals that ammonia is oxidized stepwise to NO, NO2−, and NO3− during the sensing process. Moreover, a portable wireless module based on Pt/N‐mWO3 sensor can recognize ppm‐level concentration of ammonia, which lays a solid foundation for its application in various fields.