Regulating microscopic surfaces and structures to boost n-butanol sensing performances in NiCo2O4/NiO composites

Transforming gas sensing materials from having no performance to presenting high sensing selectivity is full of challenges. For this purpose, water bath assisted sodium borohydride (NaBH4) treatment is developed and is employed to boost gas sensing dynamics of spinel structure NiCo2O4 microspheres. The n-butanol recognition, gas adsorption and carrier transport in the sensing process are tremendously optimized by etching crystal surfaces, breaking metal oxygen bonds, increasing surface area, enhancing oxygen vacancies and dislocation density, reducing crystallite size as well as forming NiCo2O4/NiO heterojunction. The NiCo2O4 microspheres treated by 0.5 M NaBH4 solution (NCO-0.5) present apparent n-butanol gas response and sensing selectivity compared to the untreated NiCo2O4 microspheres without sensing performance. The density functional theory (DFT) calculation based on adsorption energy and charge density difference further validates the evident adsorption interaction and charge transfer between heterojunction microspheres and n-butanol gas. This feasible NaBH4 treatment strategy provides more possibilities and choices for performance improvement of semiconductor gas sensing materials.