Ultra deep desulfurization of diesel over Cu/Ce-graphitic carbon nitride under visible light: a sustainable approach for clean fuel production

The combustion of sulfur-containing diesel fuels releases harmful pollutants such as sulfur oxides and sulfate particulate matter, posing significant environmental and health risks. Traditional desulfurization methods often suffer from carbon and hydrogen loss, reducing fuel efficiency. This study addresses these challenges by developing a Cu/Ce co-doped graphitic carbon nitride (Cu-Ce/CN) photocatalyst via a hydrothermal method for ultra-deep desulfurization under visible light. Comprehensive characterization techniques (SEM, XPS, XRD, UV–Vis DRS, and BET) confirmed the uniform dispersion of Cu and Ce on the CN matrix, with Cu existing as Cu⁺/Cu²⁺ and Ce as Ce³⁺/Ce⁴⁺, forming an “electron bridge” to enhance charge separation. The optimized Cu-Ce/CN (1:1 ratio) exhibited a narrowed bandgap (2.40 eV), extended visible-light absorption, and a high surface area, facilitating efficient generation of reactive oxygen species. Under optimal conditions, the system achieved a 99.27 % desulfurization ratio within 60 min, degrading refractory sulfides like dibenzothiophenes (DBTs) into sulfoxides/sulfones via photocatalytic oxidation. Cycling tests demonstrated excellent stability (95.8 % efficiency after 10 cycles), with XRD confirming structural integrity. This work presents a sustainable and efficient strategy for diesel desulfurization.