Decoupling photonic and thermal contributions for photoelectrochemical sensing of melatonin via graphene oxide nanoribbons

[Display omitted] •Enhanced faradaic currents for PEC detection of melatonin using GONRs.•Peak conversion efficiency of 1.414% for LED using GONR (150 W).•Decoupling of photo and thermal energies assisted faradaic currents.•Thermal factor ratios are low for LED but high for solar simulator. This work elucidates the photoelectrochemical (PEC) sensing of melatonin employing graphene oxide nanoribbons (GONRs) synthesized through a microwave-assisted method. GONRs served as electrocatalysts for screen-printed carbon electrodes (SPCE) to facilitate melatonin detection. We incorporated both a light-emitting diode (LED) and a solar simulator as light sources for PEC evaluations. Cyclic voltammetry revealed that the faradaic currents corresponding to melatonin oxidation on GONRs-modified SPCE were amplified under both LED and simulated solar light irradiation. Notably, the GONR (150 W) registered the most pronounced enhancement in the photo-assisted faradaic current and the highest conversion efficiency. Employing the solar simulator, certain thermal factor ratios concerning conversion efficiencies surpassed 50.0% at light intensities of both 80 mW/cm2 and 100 mW/cm2. Conversely, with the LED source, the thermal contribution remained below 15.0% of the total PEC faradaic current. We posit that obtaining conversion efficiencies devoid of thermal influences is pivotal for deepening our comprehension of PEC biosensing mechanisms.