Ultrasensitive Photoelectrochemical Sensing Of H2s Based On In-Situ Formation Of Multiple Heterojunctions

Hydrogen sulfide (H2S), as both an endogenously gaseous signaling compound and an environmentally hazardous substance, has shown great relevance to human health and ecosystem safety. However, a reliable sensing platform for the facile detection of trace H2S is still a challenge to be addressed. Herein, a AgI-TiO2 nanorods array electrode was fabricated through a hydrothermal method followed by ultrasonic impregnation treatment to construct an ultrasensitive photoelectrochemical H2S sensor. The decorated AgI could not only play a significant role in the enhancement of visible light absorbance as a narrow bandgap sensitizer but also contribute to the specific affinity towards sulfide as the recognition unit. In the presence of sulfide, multiple heterojunctions were established in situ due to I--to-S2- exchange at the AgI sites, proportionately increasing the photocurrent response of the functionalized PEC electrodes. The designed photoelectrochemical (PEC) sensing platform could achieve the quantitative determination of sulfide in a wide range of 1 similar to 1000 nM with an effective detection limit of 1.25 nM. Additionally, the detection performances for practical H2S-containing waste gas and the biological environment were also evaluated. This work could broaden a new vision of the delicate design of interfaces for ultrasensitive environmental analysis.