Electrostatic interaction mechanism based synthesis of a Z-scheme BiOI-CdS photocatalyst for selective and sensitive detection of Cu2+

A direct Z-scheme BiOI-CdS photocatalyst has been successfully synthesized by an electrostatic interaction mechanism and used for selective photoelectrochemical sensing of Cu2+. The BiOI-CdS photocatalyst shows higher photocatalytic activity and photoelectrochemical performance than pure CdS and BiOI. The photocurrent intensity generated by the BiOI-CdS-3 electrode is about 62 and 10 times of those induced by BiOI and CdS under visible-light irradiation, respectively. The enhanced photocatalytic activity is attributed to the formation of a hierarchical direct Z-scheme BiOI-CdS photocatalyst and its high Brunauer-Emmett-Teller (BET) specific surface area, which benefit the efficient spatial separation of charge and capture of visible-light. Moreover, a photoelectrochemical sensor is developed based on the selective replacement reaction between Cu2+ and CdS. The photoelectrochemical sensor is easily fabricated and presents good selectivity, acceptable detection range (0.1-100 mu M) and detection limit (0.02 mu M). It has been applied to the detection of Cu2+ ions in drinking water with a satisfactory result.