Dual mode electrochemical-photoelectrochemical sensing platform for hydrogen sulfide detection based on the inhibition effect of titanium dioxide/bismuth tungstate/silver heterojunction

Abstract A novel dual mode sensing platform is constructed for highly selective detection of H2S, attributing to the efficient electrochemical (EC) and photoelectrochemical (PEC) signal responses of the TiO2/Bi2WO6/Ag heterojunction. On the one hand, TiO2/Bi2WO6/Ag heterojunction with excellent catalytic performance for the reduction of H2O2 could be employed act as a probe, providing a remarkable EC response through an amperometric i-t method. On the other hand, this hybrid provides a photoelectric beacon with a favorable energy-band configuration. More interestingly, the EC and PEC responses of the functionalized electrodes are proportionately decreased in response to the generation of Bi2S3 and Ag2S nanoparticles upon exposure to sulfide ions. The decreased EC and PEC signals could be ascribed to the poor catalytic properties and the recombination of photoexcited electron - hole pairs of the Bi2S3 and Ag2S. Under the optimum conditions, the dual mode sensor exhibits a wide linear response in the range from 0.5 μM to 300 μM with a detection limit of 0.08 μM for the detection of H2S. Enabled by this unique sensitization mechanism, the proposed sensing platform displays an excellent analytical performance with good selectivity, reproducibility and stability, which providing an alternative pathway of H2S detecting in practical application.