Tuning charge dynamics in MIL-88A(Fe) via decoration by boron carbon nitride quantum dots for superior photocatalytic elimination performance

Abstract

The development of efficient and sustainable strategies for the removal of pharmaceutical pollutants from aqueous environments has become a critical challenge. Boron carbon nitride quantum dots (BCNQDs) have emerged as highly promising materials in photocatalysis, offering substantial performance advantages. In this study, BCNQDs were successfully integrated onto the MIL-88A(Fe) framework for the first time via a simple impregnation technique. Characterization analyses confirmed that the crystalline integrity and surface functionalities of MIL-88A(Fe) were preserved following BCNQDs decoration. HRTEM images revealed spherical BCNQDs uniformly distributed over the hexagonal rod-like MIL-88A structure. Photoluminescence (PL) and photocurrent analyses demonstrated that the integration of BCNQDs effectively suppressed electron-hole recombination. Moreover, the photocatalytic performance was significantly enhanced, with tetracycline (TC) removal efficiency increasing from 45.09 % for pristine MIL-88A to 95.19 % in the optimized MIL-88A(Fe) @BCNQDs catalyst, alongside a sixfold increase in reaction rate. This improvement was attributed to synergistic effects including enhanced charge separation, extended light absorption, favorable band structure modulation, and improved pollutant-catalyst interactions. The hybrid photocatalyst maintained high degradation efficiencies in various water matrices, achieving 84.1 % and 71.2 % removal in tap water and seawater, respectively. Radical scavenging experiments revealed a hole-dominated photocatalytic pathway, with BCNQDs functioning as efficient electron traps, thereby prolonging hole lifetimes and enabling effective oxidation under visible light. Additionally, the MIL-88A(Fe)@BCNQDs catalyst exhibited excellent reusability, retaining over 70 % efficiency after eight consecutive cycles. Overall, this study pioneers the integration of BCNQDs into a MOFbased photocatalyst, unveiling their untapped potential as next-generation, eco-friendly co-catalysts. The findings not only modulate charge carrier dynamics but also establish a new benchmark for sustainable antibiotic degradation under visible light.