Selective formation of reactive oxygen species in peroxymonosulfate activation by metal-organic framework-derived membranes: A defect engineering-dependent study

Defect engineering is an effective way to unveil relationship within structures and catalytic activities of transition metal oxides. Herein, a novel strategy has been developed for in situ generation and controlling oxygen vacancy (Ov) levels in a host lattice by varying oxygen pressure during calcination of zeolitic imidazolate framework-67 (ZIF-67) membranes. The as-prepared NFZ-5 membrane with the largest Ov content (delta, 0.912) gave the highest 1O2 production (98.3%) and PMS activated BPA degradation kinetics (k = 0.11 min-1). Advanced characterization and density functional theory (DFT) calculations have revealed the pivotal role of Ov in modifying surface chemistry of the catalytic membrane via enhancing the number of Lewis acid sites. These Lewis acid sites have facilitated the chemisorption of peroxymonosulfate (PMS) onto membrane, and the resulting reactive intermediate complexes have altered the electron transfer direction between PMS and the catalyst.