Construction of 3D porous BiOBr/MIL-101(Cr) Z-scheme heterostructure for boosted photocatalytic degradation of tetracycline hydrochloride

The challenge for efficient photocatalysis lies in the adsorption, reuse capacity and charge separation. Herein, we constructed a Büchner funnel-like three-dimensional (3D) porous BiOBr/MIL-101(Cr) Z-scheme heterostructure with large specific surface area by immobilizing BiOBr on MIL-101(Cr) framework. The BiOBr/MIL-101(Cr) hybrids exhibited efficient charge separation and increasing adsorption capacity. Importantly, Bi and Cr atoms formed an electron donor-acceptor system, which benefits to induce internal electric field (IEF) to construct Z-scheme heterostructures for promoting charge transfer and separation. In addition, MIL-101(Cr) allows the continued growth of BiOBr in the presence of (0 0 1) direction, thus exposing more (0 0 1) facet of BiOBr, which helps the electron transfer from (1 1 0) to (0 0 1) and accelerates the carrier separation. Meanwhile, the formation of 3D pore structure endowed the BiOBr/MIL-101 (BM-35, which contained 35 wt% MIL-101) with twice higher adsorption capacity than pure BiOBr. Tetracycline hydrochloride (TC-HCl) was chosen as the target pollutant to evaluate the photocatalytic performance of the as-prepared BM-35 under visible light irradiation, 94 % degradation rate of TC-HCl was achieved over BiOBr/MIL-101(Cr) after 100 min and maintained at 84 % after 5 cycles. The small pores of MIL-101(Cr) only enable water molecules to pass through, while TC-HCl cannot enter its inner pores. Moreover, the formation of BiOBr by sheet stacking has large pores that capture target pollutants onto the highly active surface and decompose them. Benefiting from the distinctive 3D structure, an adsorption-degradation cycle system was formed, the difficulty of MOF desorption was effectively overcome.