Synergistic effects of rare-metal ytterbium doping on TiO2/g-C3N5 heterostructures for enhanced photocatalytic degradation of methylene blue

Abstract

Environmental pollution, particularly from organic dye-laden wastewater, represents an escalating global challenge, necessitating the development of efficient and sustainable remediation strategies. Herein, we report the fabrication of a rare-earth element Yb-doped TiO₂/g-C₃N₅ (YTCN) heterostructured photocatalyst through hydrothermal synthesis and calcination, utilizing methylene blue (MB) and rhodamine B (RhB) as representative contaminants. The YTCN composite with an optimized mass ratio of 1:3 exhibited superior photocatalytic degradation efficiencies of 96.57 % for MB and 91.82 % for RhB with a decline rate of 0.02083 and 0.01832 min⁻¹ under 500 W xenon lamp irradiation within 105 min, corresponding to 2.2-fold and 2.1-fold improvements over pristine TiO₂, respectively. The Construction of YTCN significantly enhances photocatalytic efficiency by enhancing the separation of charge carriers, extending light absorption into the visible region, and improving overall catalytic activity. This performance enhancement is ascribed to the cooperative interactions among Yb, TiO₂, and CN, which raise charge generation, division, and carriage dynamics of photoinduced electrons (e⁻) and holes (h⁺). Furthermore, the YTCN composite demonstrated excellent recyclability and structural stability, remained close to 90 % degradation efficiency after five consecutive cycles without notable crystal degradation. These results highlight the potential of YTCN heterostructures as low-cost and robust photocatalysts for advanced wastewater treatment applications.