Zero valent boron activated ozonation for ultra-fast degradation of organic pollutants: Atomic orbital matching, oxygen spillover and intra-electron transfer

Catalytic ozonation process (COP) for degrading pollutants is limited by inefficient recovery of reactive sites on catalyst surface and scavenging of hydroxyl radical (& BULL;OH) by inorganic anions. Herein, we employed zero valent boron (ZVB) as a catalyst overcoming the abovementioned shortcomings. The established ZVB/O-3 had outstanding capability to generate & BULL;OH for near-complete decontamination in seconds with normalized kinetic coefficients far surpassing most reported works. The spontaneous dissolution of B2O3 passive layer and ZVBmediated valence circulation of adsorbed SO42- anion ensured sustainable reactive sites recovery and anti scavenging of & BULL;OH by SO42- anion, respectively. The other common inorganic anions (Cl-, HCO3- and H2PO4-) showed negligible scavenging effects on & BULL;OH-mediated reactions. Density functional theory calculation and experimental results revealed that auto-matching the empty 2p orbital of boron atom with lone pair electrons of oxygen atom in ozone played crucial roles in forming coordination bonds, resulting in strong ozone chemical adsorption by boron atom on ZVB surface. The adsorbed ozone was transformed into atomic oxygen and then & BULL;OH via a novel oxygen spillover mechanism. Moreover, the B-B bond on ZVB surface was verified to be another active site for ozone activation into & BULL;OH by intra-electron transfer mechanism which was promoted by the in-situ formed coordination bonds between ozone and ZVB. This work establishes next-generation COP by eliminating surface-and bulk-phase reaction limitations.