Single-step growth of p-type 1D Se/2D GeSexOy heterostructures for optoelectronic NO2 gas sensing at room temperature

One-dimensional (1D)/two-dimensional (2D) heterostructures offer attractive opportunities for developing high-performance gas sensors because of the unique built-in electric field at the hetero-interface, efficient charge separation and transportation, and synergetic properties of the 1D and 2D components. However, a relatively high operating temperature, insufficient gas sensitivity, and complex fabrication process present the key challenges for practical implementation. Here, we realize a p-type 1D/2D heterostructure consisting of Se belts and GeSexOy nanosheets through a single-step synthesis governed by the exfoliation-nucleation process. A type II band alignment configuration is found in the heterostructure with an effective bandgap energy of ∼1.32 eV, which covers the complete visible light spectrum. The visible-light-driven optoelectronic NO2 gas sensing performances are then investigated at room temperature. A ∼27.3% response magnitude towards 10 ppm NO2 is achieved upon irradiation with red light, with a sub-ppb limit of detection, full reversibility, excellent selectivity, and >3 months long-term stability, which is a significant improvement as a whole over those of reported 1D/2D heterostructure-based room temperature NO2 sensors. This work paves the way for realizing mixed-dimensional heterojunction-based next-generation gas sensors in a facile and effective manner.