Metal oxide patterns of one-dimensional nanofibers: On-demand, direct-write fabrication, and application as a novel platform for gas detection

To organize one-dimensional (1D) metal oxides into highly ordered and controllable architectures on the required regions remains challenging. Herein, we report for the first time the facile, versatile, and on-demand fabrication of metal oxide patterns comprising 1D nanofibers via near-field electrospinning (NFES), which have a wide variety of potential applications in sensors, optoelectronic circuits, and functional nanoelectronics. Grids, diamonds, and hexagrams of In₂O₃, Co₃O₄, and NiO nanofibers are first demonstrated, and the underlying mechanisms for fiber formation are systematically investigated with respect to the experimental parameters of NFES. Furthermore, we propose the nano-architectures as a novel gas sensing platform that exhibits an unprecedentedly high gas response (resistance ratio, S_T = 239, T: Trimethylamine) and selectivity (S_TS_E^-1 > 7, E: Ethanol) to 5 ppm trimethylamine compared with thin film counterparts (S_T = 24, S_TS_E^-1 ≈ 1). The research provides a vital breakthrough to fabricate metal oxide nano-architectures of 1D nanofibers and new platforms to design next-generation functional nanodevices for a wide range of emerging applications.