Cu_xO self-assembled mesoporous microspheres with effective surface oxygen vacancy and their room temperature NO₂ gas sensing performance

A series of Cu_xO self-assembled mesoporous microspheres (SMMs), with different and controlled morphology (virus-like, urchin-like, spherical), were synthesized by facile liquid phase approach. The morphology of the as-prepared Cu_xO SMMs was evolved from spherical to virus-like shape by controlling the ratio of DI water in solution. It can also realize the transformation from loose assembly to dense assembly by extending the reaction time. These Cu_xO SMMs exhibited good response to NO₂ gas at room temperature, benefiting from their 3D self-assembly structure. Among these the resulting virus-like CuxO SNMMs-based sensor exhibits largely enhanced response to 1 ppm NO₂ gas at room temperature. The enhanced response of the virus-like Cu₂O SMMsbased sensor can be ascribed to the high surface area, hierarchical 3D nanostructures, micropores for effective gas diffusion, the heterojunctions formed between CuO and Cu₂O, and the existence of abundant surface oxygen vacancies.