Tunable Chemical Sensing Performance of Black Phosphorus by Controlled Functionalization with Noble Metals

In this work, the effects of noble metal (Au and Pt) incorporation into black phosphorus (BP) were first investigated. Several important sensing results were observed as a result of the incorporation of Au or Pt into the BP surface. First, prior to incorporation, pristine BP only detects paramagnetic molecules, e.g., NO2 or NO. However, after incorporation with Pt, low concentration of H-2 can be detected with high response amplitude. Furthermore, the H-2 sensing performance reported in this study was found to be most sensitive as compared with that observed for a previously reported 2D H-2 gas sensor. The second significant result was obtained after incorporation with Au, where the work function of BP was varied by the transfer of electrons from the Au nanoparticles, thereby inducing the effects of n-doping on p-type pristine BP. Accordingly, the response behavior of BP to oxidizing gas changed from a p-type response (negative resistance variation) to an n-type response (positive resistance variation). In addition, a highly stable, low noise baseline was achieved in the Au-incorporated BP channel material. Finally, because of the high chemical and ambient stability of the Au or Pt, the synthesized Au- or Pt-incorporated BP systems exhibited long-term stability, which is difficult to achieve when using other doping strategies. Overall, a significant step was taken toward the efficient control of the electrical/chemical sensitization level of BP and significant enhancement of superior chemical sensing performance of BP.