Next-Generation SnS2/RGO Heterojunction for Organic Dye Degradation and Water Splitting: Water Remediation and Green Energy Conversion

Abstract Despite extensive efforts toward photocatalytic degradation of organic dye pollutants, the fundamental reaction mechanisms remain unclear. In this research, we synthesized a SnS2/RGO composite with different mass ratios and systematically investigated it as a multifunctional photo and electrocatalyst. Among the prepared samples, the SnS2/RGO composite with a mass ratio of 1:2 exhibited superior photo and electrocatalytic performance. The enhanced activity is attributed to its reduced band gap and elevated Urbach energy, which promote extended solar-light absorption, efficient photogenerated charge carrier generation, and suppressed electron−hole recombination. As a result, the optimized SnS2/RGO (1:2) composite achieved a methylene blue degradation efficiency of 93.75% under visible-light irradiation. In addition, it demonstrated excellent electrocatalytic performance, delivering a hydrogen evolution reaction overpotential of 420 mV with a Tafel slope of 108 mV dec−1, along with an oxygen evolution reaction overpotential of 250 mV and a Tafel slope of 165 mV dec−1. Radical trapping experiments revealed that majorly hydroxyl radicals and minorly photogenerated holes are the reactive species responsible for dye degradation. Further, low solution resistance and charge-transfer resistances of the optimized composite were confirmed through electrochemical impedance spectroscopy analysis, indicating enhanced charge transport kinetics. Overall, our findings highlight the SnS2/RGO catalyst as a promising nanostructured catalysts for integrated environmental remediation and sustainable energy conversion applications.