Fabrication of High-Performance Molybdenum Disulfide–Graphitic Carbon Nitride p–n Heterojunction Stabilized rGO/ITO Photoelectrode for Photoelectrochemical Determination of Dopamine

The construction of solar active photoelectrodes for photoelectrochemical purposes based on a heterojunction platform is one of the most promising strategies. Herein, a molybdenum disulfide–graphitic carbon nitride (MoS 2 –GCN) p–n heterojunction stabilized reduced graphene oxide/indium tin oxide (rGO/ITO) photoelectrode was fabricated and has been employed for the photoelectrochemical detection of the neurotransmitter dopamine (DA). First, the rGO was electrochemically reduced on an ITO slice in GO dispersion (pH = 7, −1.5–0 V potential window for 30 cycles) by using the cyclic voltammetry technique, and then the MoS 2 –GCN heterostructure was immobilized on rGO/ITO by the drop-casting method. The physicochemical characterization of the fabricated electrodes was performed by means of XRD, Raman, UV–vis DRS, EIS, PL, and SEM techniques. The type of MoS 2 and GCN semiconductors and the p–n heterojunction formation between the MoS 2 and GCN were investigated through the Hall effect and Mott–Schottky analyses. The fabricated electrode shows an enhanced photocurrent activity at 535 nm, which is confirmed from the UV-DRS measurement. The MoS 2 –GCN/rGO/ITO shows photoelectrochemical detection activity of dopamine in the linear response of 0.005–1271.93 μM with the detection limit of 1.6 nM. This MoS 2 –GCN/rGO/ITO electrode was tested for the determination of dopamine in human urine and serum samples.