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 (MoS2-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 MoS2-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 MoS2 and GCN semiconductors and the p-n heterojunction formation between the MoS2 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 MoS2-GCN/rGO/ITO shows photoelectrochemical detection activity of dopamine in the linear response of 0.005-1271.93 mu M with the detection limit of 1.6 nM. This MoS2-GCN/rGO/ITO electrode was tested for the determination of dopamine in human urine and serum samples.