Turning on the Photoelectrochemical Responses of Cd Probe-Deposited g-C₃N₄ Nanosheets by Nitrogen Plasma Treatment toward a Selective Sensor for H₂S

A selective photoelectrochemical (PEC) sensor has been designed for the signal-on detection of H2S using g-C3N4 nanosheets that were treated with N2 plasma for depositing Cd probes. It was discovered that the yielded Cd/N@g-C3N4 nanocomposites could present enhanced photocurrents of specific responses to H2S under visible light irradiation, in contrast to the ones without the pretreatment of N2 plasma showing no H2S response. Herein, the Cd probes deposited on g-C3N4 nanosheets might react with H2S to generate CdS on Cd/N@g-C3N4, forming the efficient heterojunctions. Especially, the plasma-derived N contents might act as the “bridge” to promote charge transfer between the generated CdS and g-C3N4, resulting in the “signal-on” PEC responses to H2S. A selective PEC sensor was thereby developed for sensing H2S of concentrations linearly ranging from 40.0 to 10,000 pM, with a detection limit of about 21 pM. Also, the feasibility of sensing H2S in industrial waste gas was demonstrated by recovery tests. More importantly, this N2 plasma treatment route for g-C3N4 nanosheets may open a new door toward the construction of a Cd probe-based heterojunction for the signal-on PEC sensing platform, which is promising for the wide application in the fields of environmental monitoring, food safety, and biomedical analysis.