Alkali metal doping of black phosphorus monolayer for ultrasensitive capture and detection of nitrogen dioxide.

Black phosphorus nanostructures have recently sparked substantial research interest for the rational development of novel chemosensors and nanodevices. For the first time, the influence of alkali metal doping of black phosphorus monolayer (BP) on its capabilities for nitrogen dioxide (NO2) capture and monitoring is discussed. Four different nanostructures including BP, Li-BP, Na-BP, and K-BP were evaluated; it was found that the adsorption configuration on Li-BP was different from others such that the NO2 molecule preferred a vertical stabilization rather than a parallel configuration with respect to the surface. The efficiency for the detection increased in the sequence of Na-BP < BP < K-BP < Li-BP, with the most significant improvement of + 95.2% in the case of Li doping. The Na-BP demonstrated the most compelling capacity (54 times higher than BP) for NO2 capture and catalysis (- 24.36 kcal/mol at HSE06/TZVP). Furthermore, the K-doped device was appropriate for both nitrogen dioxide adsorption and sensing while also providing the highest work function sensitivity (55.4%), which was much higher than that of BP (10.4%).