A composite of platelet-like orientated BiVO₄ fused with MIL-125(Ti): Synthesis and characterization

The development of heterojunctions is the current focus of the scientific community as these materials are visible light active and the staggered positioning of their band edges combats electron-hole recombination which is the downside of most photocatalysts. In this work, a two- step hydrothermal synthesis protocol was utilized to fabricate a novel observable-light active material, composed of platelet-like BiVO₄ and a titanium-based metal organic framework (MOF) called MIL-125(Ti). The tuning of specific morphologies, such as platelet-like in BiVO₄, provides the exposure of most reactive facets which are more reactive towards photooxidation of organics in water, thus increasing their efficiency. The as-synthesized heterojunction was characterized by Transmission electron microscopy (TEM), scanning transmission microscopy (SEM), X-Ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), X-Ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectra. The formation of the heterojunction lead to a positive shift of the 3-2 Bi:Ti valence band (VB) (1.78 eV) when compared to 1.27 eV VB position of BiVO₄. The PL and photoelectrochemical measurements revealed that the heterojunction photocatalyst designated 3-2 Bi-Ti demonstrated inhibited recombination rate (platelet-like BiVO₄ > 3-2 Bi:Ti (PM) > MIL-125 > 1-1 Bi:Ti > 2-3 Bi:Ti > 3-2 Bi:Ti) and highly efficient interfacial charge shuttle between platelet-like BiVO₄ and MIL-125(Ti) through the formed n-n junction.