Synthesis and Characterization of SnO2/S,N-Carbon Quantum Dots as Photoelectrochemical Water Splitting Material

Abstract

Given the growing global demand for renewable energy and the need for sustainable hydrogen production, the development of efficient photoelectrochemical systems for water splitting has become a critical area of research in addressing the energy crisis and reducing greenhouse gas emissions. This study investigates the synthesis of SnO₂ thin film photoanodes using ultrasonic spray pyrolysis (USP) and hydrothermal methods, with the aim of evaluating the effects of S,N-carbon quantum dot (CQD) modification on photoelectrochemical performance. The S,N-CQDs solution was varied in volume (2.5, 5, 7.5, and 10 mL) and applied to the SnO₂ thin films. The resulting SnO₂ microstructure exhibited a spherical morphology with distinct atomic concentrations of Sn and O. Photoelectrochemical characterization, performed via linear sweep voltammetry (LSV) and cyclic voltammetry (CV), demonstrated that the SnO₂ thin film modified with 7.5 mL of S,N-CQDs solution produced the highest photocurrent density of 0.0356 mA/cm², along with an optimal photoconversion efficiency (PCE) of 0.0084%. Furthermore, the SnO₂/S,N-CQDs photoanode with 7.5 mL of S,N-CQDs exhibited a double-layer capacitance (C_dl) of 0.1175 mF/cm², indicating enhanced electrochemical active sites. These findings suggest that the incorporation of S,N-CQDs into SnO₂ thin films effectively increases the active surface area, thereby improving the efficiency of the photoelectrochemical water splitting process.