Nitrogen-Doped Carbon Nanofibers Embedded with CuOx/TiO2 for ppb-Level H2 Sensing at Room Temperature for Potential Application of Lithium-ion Battery Thermal Runaway

Abstract It is crucial to detect hydrogen (H2) release from battery packs to provide early warning of battery thermal runaway. In this article, the hollow octahedral CuOx/TiO2 were prepared using an efficient MOF template strategy, and nitrogen (N) -doped carbon (C) nanofibers embedded with CuOx/TiO2 were designed by electrospinning, which were CuOx/TiO2@NCFs. The hollow heterojunctions (CuOx/TiO2) formed based on MOF templates can reduce the recombination rate of carriers in TiO2, and DFT calculations reveal charge transfer occurring at the heterojunction, with a substantial migration of electrons from TiO2 to CuO, significantly enhancing the ability of TiO2 surface to adsorb H2. Simultaneously, the nanofibers composed of CuOx/TiO2 and PAN contain substantial amounts of nitrogen and carbon. The introduced N atoms can activate the adjacent C atoms, the 3D framework constructed from N-doped C nanofibers exhibits extremely strong electron transport capability. At the optimal TiO2:PAN ratio of 4.0:1, the sensor achieves the response of 48% toward 10 ppm H2, and can detect as low as 20 ppb H2 at room temperature, which is a potential competitive candidate for monitoring LIBs thermal runaway.