Highly Active Co‐Based Catalyst in Nanofiber Matrix as Advanced Sensing Layer for High Selectivity of Flexible Sensing Device

An efficient and economic sensing material for flexible chemical sensors is increasingly in great demand as a result of its potential application in the healthcare and environmental detection systems. Endowing the nanomaterials with high active facets serves as a promising method for the design of nanomaterials with advanced functionalities. New physicochemical properties of chemical sensor can be obtained by using high active facets nanoparticles combined in one‐dimensional (1D) nanofiber/wires. However, it remains a great challenge to conduct the development of 1D heterostructure sensing materials with high selectivity, in particular the ones that can perform under room temperature. Here, a high performance flexible sensing device based on Co 3 O 4 nanoparticles with specific (112) facet in α‐Fe 2 O 3 nanofiber is reported. The heterointerfaces and grain boundary allow the fast electrons transportation in sensing reactions and the (112) facets in Co 3 O 4 nanoparticles provide a large number of highly active sites where the selective absorption of ammonia gas molecules occurs. Consequently, the flexible gas sensor exhibits ultrahigh sensitivity (417%) and mechanical stability to ammonia gas molecules, which are proved by using density functional theory calculations.