Enhancing the decomposition of refractory contaminants on SO42--functionalized iron oxide to accommodate surface SO4- generated via radical transfer from OH

Deciphering Evolution Pathway of Supported NO3• Enabled via Radical Transfer from •OH to Surface NO3– Functionality for Oxidative Degradation of Aqueous Contaminants

“…We previously envisioned a unique • OH → supported SO 4 •– (SO 4 •– SUP ) pathway under an e – -abundant electric condition, for which SO 4 2– functionalities are anchored on d -block metal oxide surfaces (e.g., Fe 2 O 3 , NiO, and Fe-substituted Mn 3 O 4 ) to expedite H 2 O 2 scission and radical transfer from • OH to supported SO 4 2– (SO 4 2– SUP ) via a series of elementary steps ( Figure 1 A and C). 26 − 28 Initially, a lone pair of electrons on H 2 O 2 bind with Lewis acidic surface M δ+ species (Fe 2+ , Ni 2+ , or Mn 2+/3+ ) to produce M δ+ ···H 2 O 2 prior to heterolytic H 2 O 2 splitting to form surface M (δ+1)+ ··· • OH and surface-unbound – OH ( Figure 1 A). 26 − 28 M (δ+1)+ ··· • OH then desorbs • OH, by which SO 4 •– productivity via the • OH → SO 4 •– SUP route is directed.…”

“… 26 − 28 Initially, a lone pair of electrons on H 2 O 2 bind with Lewis acidic surface M δ+ species (Fe 2+ , Ni 2+ , or Mn 2+/3+ ) to produce M δ+ ···H 2 O 2 prior to heterolytic H 2 O 2 splitting to form surface M (δ+1)+ ··· • OH and surface-unbound – OH ( Figure 1 A). 26 − 28 M (δ+1)+ ··· • OH then desorbs • OH, by which SO 4 •– productivity via the • OH → SO 4 •– SUP route is directed. This indicates that the • OH desorption stage dominates the overall • OH → SO 4 •– SUP route as the rate-determining step (red arrow in Figure 1 A).…”

“…This indicates that the • OH desorption stage dominates the overall • OH → SO 4 •– SUP route as the rate-determining step (red arrow in Figure 1 A). 26 − 28 Finally, M (δ+1)+ on the surface is reduced to M δ+ via e – reduction for the recycling H 2 O 2 scission cycle. 26 − 28 Meanwhile, surface-unbound • OH migrates to and interacts with the SO 4 2– SUP functionality, undergoing transition from SO 4 2– ··· • OH to SO 4 •– ···OH – to SO 4 •– upon the release of OH – to the aqueous medium (SO 4 2– /SO 4 •– in exchange for NO 3 – /NO 3 • in Figure 1 C).…”

“… 26 − 28 Finally, M (δ+1)+ on the surface is reduced to M δ+ via e – reduction for the recycling H 2 O 2 scission cycle. 26 − 28 Meanwhile, surface-unbound • OH migrates to and interacts with the SO 4 2– SUP functionality, undergoing transition from SO 4 2– ··· • OH to SO 4 •– ···OH – to SO 4 •– upon the release of OH – to the aqueous medium (SO 4 2– /SO 4 •– in exchange for NO 3 – /NO 3 • in Figure 1 C). 26 − 28 SO 4 •– SUP can radicalize or destabilize contaminant via e – exchange prior to the recovery of SO 4 2– for reactivating radical interconversion of • OH ↔ SO 4 •– SUP .…”

GSH‐Depleted Nanozymes with Dual‐Radicals Enzyme Activities for Tumor Synergic Therapy

“…Recently, it has been revealed that the sulfate ions (SO 4 2− ) on the surface of iron oxide nanoparticles could be converted into SO 4 •‐ in the presence of • OH (Fe‐SO 4 2− + • OH→ Fe‐SO 4 •− + OH − ). [ 9,11 ] Based on this, the researchers have prepared micron‐scale particles of Fe 3 O 4 nanocrystals coated Schwertmannite (Sch) matrix for rapid degradation of organic matter. [ 12,13 ] Such Sch@Fe 3 O 4 hybrid could effectively stimulate SO 4 2− species of Sch to produce SO4 •− through heterogeneous Fenton reactions.…”