Facile In-Situ synthesis of silicon Carbide-Graphitic carbon nitride composite for enhanced photocatalytic uranium (VI) recovery

Abstract

This study successfully synthesized a novel photocatalyst, a composite of silicon carbide and graphitic carbon nitride, which achieved efficient photocatalytic reduction of uranium (VI) under visible light irradiation. The optimal loading of silicon carbide in the composite was determined to be SiC15@g-C3N4, which significantly enhanced the optoelectronic properties of graphitic carbon nitride, improving the separation efficiency of photogenerated electron-hole pairs and extending the electron lifetime from 1.73 ns to 3.96 ns. Furthermore, the adding of silicon carbide effectively modified the band structure of graphitic carbon nitride, with the conduction band position shifting from −0.74 eV to −1.18 eV, thereby enhancing the reducibility. In photocatalytic reduction experiments, the SiC15@g-C3N4 composite demonstrated exceptional reduction efficiency, achieving a remarkable 100 % photocatalytic reduction rate within 30 min, which is significantly superior to that of pristine g-C3N4. The study revealed that superoxide radicals (·O2-) are the main reactive species in the reaction, leading to the formation of uraninite (UO2) as the reduced product. These findings not only deepen the understanding of the synergistic effects between SiC and g-C3N4 but also provide new perspectives for the design of efficient photocatalysts. The SiC15@g-C3N4 composite shows potential applications in environmental remediation and nuclear waste management.