Cocrystallization Enabled Spatial Self‐Confinement Approach to Synthesize Crystalline Porous Metal Oxide Nanosheets for Gas Sensing

Crystalline metal oxide nanosheets show exceptional catalytic performance owing to the large surface-to-volume ratio and quantum confinement effect. However, it is still a challenge to develop a facile and general method to synthesize metal oxide nanosheets. Herein, we report a cocrystallization induced spatial self-confinement approach to synthesize metal oxide nanosheets. Taking the synthesis of SnO₂ as an example, the solvent evaporation from KCl and SnCl₂ solution induces the cocrystallization of KCl and K₂ SnCl₆ , and the obtained composite with encapsulated K₂ SnCl₆ can be in situ converted into SnO₂ nanosheets confined in KCl matrix, after water washing to remove KCl, porous SnO₂ nanosheets can be obtained. Notably, a series of metal oxide nanosheets can be obtained through this general and efficient green route. In particular, porous CeO₂ /SnO₂ nanosheets with improved surface O^- species and abundant oxygen vacancies exhibit superior gas sensing performance to 3-hydroxy-2-butanone.