Constructing Z-scheme β-Bi2O3/ZrO2 heterojunctions with 3D mesoporous SiO2 nanospheres for efficient antibiotic remediation via synergistic adsorption and photocatalysis

A series of Z-scheme β-Bi2O3/ZrO2 heterojunction composites containing three-dimensional (3D) mesoporous silica nanospheres (MSNs) were synthesized as efficient catalysts for antibiotic remediation. The obtained MSN/β-Bi2O3/ZrO2 ternary composites possess novel lamellar cross structure, which is well constructed by β-Bi2O3 nanosheets, 3D MSNs, and ZrO2 nanoparticles. The optimal sample BZS-2 (Bi: Zr: Si = 1: 0.4: 0.33) shows an adsorptive-photocatalytic removal efficiency of 92.7% towards levofloxacin (LVF) and a total organic carbon (TOC) removal efficiency of 60.0% under simulated solar light irradiation for 100 min. BZS-2 can also remove 90.1% and 91.2% of tetracycline hydrochloride (TC) and oxytetracycline hydrochloride (OTC), respectively, and the maximum adsorption capacity of TC over BZS-2 is almost 10 times that of β-Bi2O3. The improvement of photocatalytic activity can be mainly attributed to the enhanced visible-light adsorption capacity and more efficient separation of photogenerated electron–hole pairs. A possible Z-scheme photocatalytic mechanism of β-Bi2O3/ZrO2 heterojunctions based on valence band offset (ΔEVBO) and conduction band offset (ΔECBO) is proposed. This study provides an efficient way to construct novel mesoporous ternary photocatalyst with increased accessible surface area and active sites for treatment of antibiotics by synergistic adsorption and photocatalysis.Graphical abstract