Enhanced formaldehyde gas sensing performance of ternary CuBi2O4 oxides through oxygen vacancy manipulation and surface platinum decoration

Abstract

Oxygen vacancy construction has been regarded as an effective method to enhance the sensing performance of the gas sensors. Herein, in this work, two CuBi2O4 composites with nanoflowers (CBOF) and nanospheres (CBOS) structures were synthesized with similar BET specific surface area, pore size distributions and exposed facets. However, a higher bulk oxygen vacancy concentration was found in the CBOS composites, bringing a higher carrier concentration and lower baseline resistance. As a consequence, the CBOS sensors exhibited better formaldehyde gas sensing performance (10.9–60 ppm gas) than that of the CBOF sensors (5.8). After treated in NaBH4 solutions, both composites exhibited enhanced surface adsorbed oxygen species and formaldehyde sensing response, owning to the generation of more surface oxygen vacancies to facilitate the surface adsorptions and redox reactions. After that, the Pt nanoparticles were decorated on the CBOS surface with a reduced method. The formaldehyde sensing response and selectivity were further enhanced due to the surface catalytic activity of the Pt nanoparticles. This work proves that CuBi2O4 composites can be an ideal sensing platform through oxygen vacancy construction and noble metal sensitization, and will facilitate the development of p-type ternary sensing materials.