Zeolite-modified electrodes for electrochemical sensing of heavy metal ions e Progress and future directions

Developing low-cost and efficient electrodes for sensing heavy metal ions (HMIs) such as cadmium [Cd2 thorn ], lead [Pd2 thorn ], arsenic [As3 thorn ], and mercury [Hg2 thorn ] ions in water bodies/others in environmental samples is of immense importance to assessing ecological toxicity. Among different electrodes, zeolite modified electrodes (ZMEs) have received considerable attention in electrochemical sensing of HMIs due to their reliability and robustness in a wide range of environmental conditions. Therefore, this paper aims to review the recent progress in customizing zeolites (altering shape and sizes, pore spaces, functionality, and ion exchange properties) using metals and metal-oxides, polymers, and carbon materials to develop efficient ZMEs for HMI sensing. For instance, the physical and chemical properties of zeolites promoted favorable size and structural features for electrochemical analysis of HMI. Moreover, the pore size and shape of zeolite can be customized via the advanced synthesis process, which makes it an ideal catalyst matrix for ion exchange to achieve highly selective HMI sensing. Furthermore, we have critically analyzed the advances in the fabrication of ZMEs, sensing mechanisms, advantages over existing elec-trodes, and limitations in the perspective of improving the performances of such electrodes in the future. Thus, the present review will guide researchers to develop robust HMI sensing elements with high sensitivity and selectivity for environmental applications.(c) 2023 Elsevier Ltd. All rights reserved.