Black Phosphorus-Titanium Dioxide Composites for Trace Nitrogen Dioxide Sensing at Room Temperature

Black phosphorus (BP) as one novel two-dimensional material has exhibited a specific detection selectivity toward hazardous NO 2 gas due to their strong adsorption energy and efficient electron transfer. However, the inherent shortcomings including sluggish response, reluctant recovery and fragile water-tolerance impede its further exploration. To overcome these obstacles, chemiresistive sensors featuring composites of BP nanosheets-porous titanium dioxide (TiO 2 ) nanoparticles as the sensing layer were fabricated in this work. Compared with pure BP counterpart, BP-TiO 2 sensor delivered favorable performance at room temperature (20 o C) in terms of boosted response (i.e., 66.6% vs. 40.3% toward 25 ppb NO 2 ), more sufficient desorption, accelerated response/recovery speeds, and intensified humidity-resistant properties by occupying high-energy sorption sites when synthesizing the composites. Through subtly optimizing the mass fraction between BP and TiO 2 components, the composite sensor with a mass fraction of 1:1 achieved the best sensing capability. Also, various characterization techniques including AFM, SEM, TEM, XRD, XPS and Raman spectrum were employed to interpret the outcomes. The proposed BP-TiO 2 sensor afforded alternative strategies to impel further BP applications in the fields of exhaled breath monitoring and ultralow emission. Figure 1