Surface Chemistry Determined Electrochemical Sensing Performance of Red Phosphorus and Single Walled Carbon Nanotube Composites

Red phosphorus (RP) is a promising electrochemical sensing material owing to its abundant surface groups and reactive sites. In this study, a sodium dodecyl sulfate-assisted phosphorus-amine approach is employed to tune surface chemistry of RP nanoparticles. During the transition of the polyphosphorus-amine anion to RP, the cleavage of P  O  P bond and the formation of P  O  C bond are monitored by in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy. The formed P  O  C bonds that are originated from the P  O  reactive sites are theoretically revealed with the density functional theory calculations, charge density difference, and X-ray photoelectron spectroscopy. The energies of optimized aromatic and aliphatic P  O  C bonds are −2.51 and −2.65 eV, respectively. To explore electrochemical sensing applications, RP nanoparticles are in situ grown on single-walled carbon nanotube (SWCNT). Such a stable RP/SWCNT suspension is applied to fabricate the RP/SWCNT integrated arrays via a template-filtration method. Such an array is efficient for sensitive and selective monitoring of p-phenylenediamine on hair dyes. This study provides insights into surface chemistry of RP, its roles in electrochemical sensing applications, and an approach to produce high-performance RP sensors at large scales.