Visible-light-prompted photoelectrochemical sensors fabricated using ErNbO/P@g-CN/SnS nanocomposite for detecting mercury ion in environmental water samples.

Photoelectrochemical (PEC) detection technology is key for fighting pollution, leveraging the photoelectric conversion of the photoelectrode material. A specialized photoelectrode was developed to detect Hg ions with exceptional sensitivity, utilizing an anodic PEC sensor composed of ErNbO/P@g-CN/SnS ternary nanocomposite. Rare earth metal niobates (RENs) were chosen due to their underexplored potential, whose performance was enhanced through bandgap engineering and surface modification, facilitated by P@g-CN as an immobilization matrix and SnS, belonging to the I-IV semiconductors category fostering hybrid heterojunction formation for boasting optical properties and suitable redox potentials. Introducing Hg into the system, a specific amalgamation reaction occurs between reduced Hg and Sn. This reaction obstructs electron transfer to the FTO electrode surface, leading to the recombination of charges. The proposed PEC sensor exhibited remarkable analytical performance for Hg detection, high sensitivity, a detection limit of 0.019 pM, excellent selectivity, and a detectable concentration range of 0.002-0.15 nM. Additionally, it demonstrated good recovery and low relative standard deviation when analyzing Hg in water samples, highlighting the potential application of the heterostructure in detecting heavy metal ions via PEC technology.