Efficient photocatalytic degradation with a lattice-matched α-Bi2O3/Co3O4 Z-scheme heterojunction: An integrated experimental and DFT study

Given the crucial impact of lattice matching on the charge-transfer efficiency and overall catalytic activity in heterojunctions, we pre-designed an α-Bi 2 O 3 /Co 3 O 4 photocatalytic system with high lattice matching to reduce dangling bonds and lattice mismatches in heterojunctions (A-axis: 2.77 %, B-axis: 0.86 %). The α-Bi 2 O 3 /Co 3 O 4 heterojunction was synthesized using a coprecipitation strategy and showed a wide optical absorption range, with enhanced absorption beyond 420 nm, and ideal photoelectrochemical responses (the highest current intensity: 0.26 μA (cm 2 ) −1 ). Under simulated sunlight irradiation, the heterojunction removed 97.30 % and 85.32 % of methylene blue and tetracycline, respectively, within 120 min. The degradation was corroborated by total organic carbon removal efficiencies, with methylene blue achieving 92.51 % and tetracycline 87.33 % within 120 min, indicative of the effective mineralization process. Our density functional theory calculations indicated that α-Bi 2 O 3 and Co 3 O 4 generated an internal electric field during the Fermi equilibrium process, which caused the conduction band electrons of α-Bi 2 O 3 to flow towards the valence band of Co 3 O 4 , forming a Z-scheme electron flow. Electrons and holes could be separated and transported in heterojunctions with low interface resistance and then react with dissolved oxygen to generate highly active OH and O 2 − radicals, which induced the efficient degradation of organic pollutants. We explored the key influence of structure on catalytic activity on lattice matching and analyzed the catalytic mechanism of α-Bi 2 O 3 /Co 3 O 4 heterojunctions in terms of charge properties. Our findings should serve as a crucial reference for developing excellent structured photocatalytic materials.