Ultrasensitive photoelectrochemical sensing of H2S based on in-situ formation of multiple heterojunctions

Hydrogen sulfide (H 2 S), 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 H 2 S is still a challenge to be addressed. Herein, a AgI-TiO 2 nanorods array electrode was fabricated through a hydrothermal method followed by ultrasonic impregnation treatment to construct an ultrasensitive photoelectrochemical H 2 S 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-S 2− 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 ∼ 1000 nM with an effective detection limit of 1.25 nM. Additionally, the detection performances for practical H 2 S-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.