A novel self-powered electrochemical sensor based on a H2O2 photoelectrochemical cell for selective detection of Cd2+

Compared to traditional electrochemical methods, the self-powered electrochemical sensor (SPES) offers a simple configuration and cost-effective detection device that operates without external power. In this work, we designed a visible-light-driven SPES based on a membrane-free H2O2 photoelectrochemical cell (PEC-SPES). This device used the BiOI/g-C3N4 composite as the photoanode and iron phthalocyanine (FeIIPc) as the photocathode. The optimized BiOI/g-C3N4 composite, featuring a high specific surface area and a p-n heterojunction, achieved photocurrent densities of up to 0.23 mu A/cm2. Furthermore, the SPES demonstrated a detection limit as low as 0.033 mu M (S/N = 3) towards Cd2+, owing to the adsorption facilitated by oxygen-containing functional groups and it-electrons of the BiOI/g-C3N4 composite. Our work offers new insights for coupling visible-light-driven PEC with an electrochemical sensor for detecting heavy metal ions.