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

It is crucial to detect hydrogen (H 2 ) release from battery packs to provide early warning of battery thermal runaway. In this article, the hollow octahedral CuO x /TiO 2 were prepared using an efficient MOF template strategy, and nitrogen (N) -doped carbon (C) nanofibers embedded with CuO x /TiO 2 were designed by electrospinning, which were CuO x /TiO 2 @NCFs. The hollow heterojunctions (CuO x /TiO 2 ) formed based on MOF templates can reduce the recombination rate of carriers in TiO 2 , and DFT calculations reveal charge transfer occurring at the heterojunction, with a substantial migration of electrons from TiO 2 to CuO, significantly enhancing the ability of TiO 2 surface to adsorb H 2 . Simultaneously, the nanofibers composed of CuO x /TiO 2 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 TiO 2 :PAN ratio of 4.0:1, the sensor achieves the response of 48% toward 10 ppm H 2 , and can detect as low as 20 ppb H 2 at room temperature, which is a potential competitive candidate for monitoring LIBs thermal runaway.