Exfoliated black phosphorus gas sensing properties at room temperature

Room temperature gas sensing properties of chemically exfoliated black phosphorus (BP) to oxidizing (NO2, CO2) and reducing (NH3,H2, CO) gases in a dry air carrier have been reported. To study the gas sensing properties of BP, chemically exfoliated BP flakes have been drop casted on Si3N4 substratesprovided with Pt comb-type interdigitated electrodes inN2 atmosphere. Scanning electron microscopy and x-ray photoelectron spectroscopy characterizations show respectively the occurrenceof a mixed structure, composed of BP coarse aggregates dispersed on BP exfoliated few layer flakesbridging the electrodes, and a clear 2p doubletbelongingto BP, which excludes the occurrence ofsurface oxidation. Room temperature electrical tests in dry air show a p-type response of multilayer BPwith measured detection limits of 20 ppb and 10 ppm toNO2 andNH3 respectively. No response toCOandCO2 has been detected, while a slight but steady sensitivity toH2 has been recorded. The reported results confirm, on an experimental basis, what was previously theoretically predicted, demonstrating the promising sensing properties of exfoliated BP.