The metal-organic framework supported gold nanoparticles as a highly sensitive platform for electrochemical detection of methyl mercury species in the aqueous environment

Mercury readily methylates to form extremely toxic methylmercury (CH3Hg+) that seriously imparts central nervous systems' functionality in humans and animals. Therefore, the development of rapid CH3Hg+ determination methods for the detection of environmentally relevant concentrations is a research priority. We developed an electrochemical technique to detect CH3Hg+ with minimal sample preparations, cost-effectively. Gold nanoparticles (AuNPs) were synthesized on metal-organic frameworks (MOFs) in a facile way using potassium borohydride as a reductant. An electrochemical sensor was developed using Au nanoparticles and zeolitic imidazolate framework-67 (Au/ZIF67) modified glassy carbon electrode (Au/ZIF67 GCE) for the determination of CH3Hg+. The linear stripping current responses were ranging from 1 µg/L to 25 µg/L [CH3Hg+], with 0.571 µA/µgL-1 sensitivity and 0.05 µg/L detection limit. The outstanding performance of Au/ZIF67 modified GCE for CH3Hg+ detection might be attributed to the unique hollow structure and active Co sites of the ZIF67 skeleton and catalytic activity of AuNPs. The new electrochemical sensor shows good stability and no interference by metal ions in the matrix. The Au/ZIF67 modified GCE sensor shows a good promise in detecting CH3Hg+ in natural water.