Design of high-performance electrochemistry sensors: Elucidation of detection mechanism by DFT studies

Hg2+ contamination posed significant risks to human health and the environment even at low concentrations. And it can cause severe damage to the organs, such as kidney failure and various motor disorders. Herein, the high-performance electrochemistry sensor for Hg2+ had been designed, and the sensor properties were greatly improved, which mainly come from the introduced Schottky barrier to the CuO/Cu/PPy electrode. Benefiting from physical barrier, CuO/Cu/PPy electrode exerted charge redistribution and high Hg2+ adsorption energy, which was experimentally and theoretically proven. The analyses of mulliken charge indicated that the charge density gaps of Schottky barrier and PPy were getting bigger and bigger with the adsorption of Hg2+, which accelerated the reaction kinetics and was more conducive to Hg2+. As expected, excellent sensor capability, specifically in the sensitively detected Hg2+ in a wide linear range from 50 pM to 100 nM with a low LOD of 29.35 pM, and easily distinguish target molecules in seawater with an outstanding recovery. The experimentally and theoretically results indicated that introduced physical barrier to electrochemistry sensors was an effective means for development of novel sensors. •The reasons for the excellent sensing performance were analyzed through experiments and theoretical calculations.•A wide linear range and a low LOD were achieved.•Due to the physical barrier played a crucial role in electrochemical detection, the sensor can work in seawater.