One-step electrochemical modification of pencil graphite electrode with reduced graphene oxide/phosphotungstic acid/sol–gel, and its application to the trace analysis of lead(II)

To determine lead ions, the reduced graphene oxide/phosphotungstic acid (rGO/PWA) composite was used to modify the pencil graphite electrode (PGE). To enhance the efficiency of the sensor, sol–gel was used for the modification, which had a favorable effect of stabilizing, dispersing and increasing the effective sites produced by rGO/PWA. Instead of the traditional sol–gel film preparation method, the modifier composite (rGO/PWA/Sol-Gel) was deposited on the electrode surface electrochemically in a single step in a suitable solution by applying a constant potential. During the sol–gel film formation process, film mesoporous channels were used as a model for the growth of rGO/PWA conductor modifier arrays. The whole process of electrodeposition on the electrode surface took place in a short time (120 s). The modifier was evaluated by SEM and EIS. The effective surface of the modified electrode was calculated, and it was shown that the conductivity of the electrode was increased after using the sol–gel substrate. The modified electrode was used to measure Pb(II) using the differential pulse anodic stripping voltammetry (DPASV) method. Several influential factors were optimized in the designing sensor and measurement of Pb(II). A linear range of 5.0 × 10-10–5.0 × 10-7 M and a detection limit of 2.2 × 10-11 can be accessed by the modified electrode. The measurement of Pb(II) was performed successfully in real samples of drinking water and urine.