Hg2+-integrated ZIF-8-derived ZnS nanocubes enabling enhanced “signal-on” photoelectrochemical sensing of hydrogen sulfide via in-situ formation of type-II heterojunction

A simulated sunlight-driven photoelectrochemical (PEC) sensor has been developed for quantitative analysis of hydrogen sulfide (H 2 S) with “signal-on” output by Hg 2+ -integrated ZnS nanocubes (Hg 2+ @ZnS NCs). Herein, hollow ZnS NCs were firstly prepared by the ZIF-8-derived soft-template method. Subsequently, Hg 2+ probing ions were doped into the porous structures of these ZnS NCs through an adsorption reaction, yielding Hg 2+ @ZnS NCs. It was observed that Hg 2+ @ZnS-based PEC sensor could exhibit slightly enhanced PEC responses over pristine ZnS, attributed to the adsorption of Hg 2+ on ZnS surface, which may modulate surface states/defects and band structures to suppress surface recombination. More importantly, after the addition of H 2 S, the in-situ growth of HgS@ZnS with a type-II heterojunction enables enhanced photocurrent response in developed sensor by promoting efficient spatial charge separation and transfer. A PEC sensing platform with exceptional sensitivity and selectivity has been established for H 2 S quantification, covering a linear range of 0.05–10 nM and a detection limit of 32 pM, which may serve as a guideline for the design of PEC sensors for real-world H 2 S analysis in complex matrices like environmental wastewater and industrial waste gas.