Synthesis of Bismuth-Nanoparticle-Enriched Nanoporous Carbon on Graphene for Efficient Electrochemical Analysis of Heavy-Metal Ions

A BiNPs@NPCGS nanocomposite was designed for highly efficient detection of multiple heavy-metal ions by in situ synthesis of bismuth-nanoparticle (BiNP)-enriched nanoporous carbon (NPS) on graphene sheet (GS). The NPCGS was prepared by pyrolysis of zeolitic imidazolate framework-8 (ZIF-8) nanocrystals deposited on graphene oxide and displayed a high surface area of 1251m(2)g(-1) and a pore size of 3.4nm. BiNPs were deposited on NPCGS in situ by chemical reduction of Bi3+ with NaBH4. Due to the restrictive effect of the pore/surface structure of NPCGS, the BiNPs were uniform and well dispersed on the NPCGS. The BiNPs@NPCGS showed good conductivity and high effective area, and the presence of BiNPs allowed it to act as an efficient material for anodic-stripping voltammetric detection of heavy-metal ions. Under optimized conditions, the BiNPs@NPCGS-based sensor could simultaneously determine Pb2+ and Cd2+ with detection limits of 3.2 and 4.1nM, respectively. Moreover, the proposed sensor could also differentiate Tl+ from Pb2+ and Cd2+. Owing to its advantages of simple preparation, environmental friendliness, high surface area, and fast electron-transfer ability, BiNPs@NPCGS showed promise for practical application in sensing heavy-metal ions.