Laser-ablated violet phosphorus/graphene heterojunction as ultrasensitive ppb-level room-temperature NO sensor

Abstract

Two dimensional (2D) materials are promising gas sensing materials, but the most of them need to be heated to show promising sensing performance. Sensing structures with high sensing performance at room-temperature are urgent. Here, another 2D material, violet phosphorus (VP) nanoflake is investigated as gas sensing material. The VP nanoflakes have been effectively ablated to have layers of 1–5 layers by laser ablation in glycol. The VP nanoflakes are combined with graphene to form VP/G heterostructures-based NO sensor. An ultra-high gauge factor of 3 × 107 for ppb-level sensing and high resistance response of 59.21% with ultra-short recovery time of 6s for ppm-level sensing have been obtained. The sensing mechanism is also analysed by density functional theory (DFT) calculations. The adsorption energy of VP/G is calculated to be −0.788 eV, resulting in electrons migration from P to N to form a P−N bond in the gap between VP and graphene sheet. This work provides a facile approach to ablate VP for mass production. The as-produced structures have also provided potential gas sensors with ultrasensitive performance as ppb-level room-temperature sensors.