Dye-sensitized n-n heterojunction {001}TiO2@NH2-MIL-101(Fe) for degradation of rhodamine B under visible light

Abstract

The {001}TiO₂@NH₂-MIL-101(Fe) heterojunctions (MT-x) crafted by the fusion of components {001}TiO₂ and NH₂-MIL-101(Fe) possesses an optimally positioned conduction band. Consequently, MT-x is capable of sensitizing Rhodamine B (RhB) and effectuating its degradation via a photocatalytic mechanism that is driven by visible light irradiation. Specifically, the n-n heterojunction designated as MT-3 achieved a RhB removal rate of 94.45 % within a 3-hour period, which corresponds to a 5.4-fold and 2.2-fold enhancement over the degradation rates observed for {001}TiO₂ and NH₂-MIL-101(Fe), respectively. Photo-electrocatalytic performance analyses showed that the n-n heterojunction MT-3 effectively inhibited electron-hole pair recombination. Moreover, the intimate interfacial contact between monomer materials enhanced the separation and transfer of photogenerated carriers, which indicates that MT-3 has excellent photocatalytic performance. The free radical trapping and EPR results indicated that ·O₂^- plays a major role in the photocatalytic degradation of RhB by MT-3, followed by h⁺ and ·OH. Furthermore, high-resolution liquid chromatography-mass spectrometry was employed to investigate photodegradation intermediates. The destruction of the RhB structure significantly reduced the environmental pollution associated with organic dye. The MT-x heterojunction exhibits remarkable potential for practical applications in organic contaminants removal.