Bismuth and nitrogen co-doped graphene oxide for efficient electrochemical sensing of Pb(II) by synergistic dual-site interaction.

Carbon electrode materials have been widely explored with surface functionalization to find novel properties and electrochemical applications. The study reports ionic lead (Pb2+) detection over bismuth (Bi) and nitrogen (N) atomically co-doped graphene oxide (GO) flakes in an electrochemical sensor and their facile synthesis by a combined wet chemical and photochemical process. Both surface state and electronic transition manipulated by the heteroatom doping were characterized by spectroscopic analyses. The Bi- and N-added GO sensors exhibited a relatively higher sensitivity for the detection of Pb2+ ions in acetate buffer solution than the bare GO one as measured by square wave anodic stripping voltammetry (SWASV), and their stripping current and potential are dependent upon the dopant content. The Bi and N co-doped GO electrode showed a noticeable electrocatalytic activity toward Pb2+ detection compared with the singly Bi- and N-doped GO ones as measured by cyclic voltammetry (CV). Formation of electroactive Bi and N dual sites exerts a major influence on the adsorption of Pb2+ ions and deposition-stripping process, and their synergistic interaction in the electron transfer and catalysis is responsible for the remarkably enhanced sensing activity. The co-doped GO sensor reveals a linear dependence of the current response and peak potential on the Pb2+ concentration and offers sensitive assaying of Pb2+ ions with a quite low limit of detection (LOD) of 10.9 pM and low limit of quantification (LOQ) of 36.4 pM. Its analytical performance with good selectivity against several interfering ions and determination in tap water samples was acquired. Results demonstrate the feasibility of coupling metal with nonmetal co-dopants to tailor the electrical conduction and surface reactivity of the two-dimensional (2D) carbon materials toward efficient sensing operation. [ABSTRACT FROM AUTHOR]