Overcoming the symmetric electronic structure of single-atom catalysts (SACs) to promote the cleavage of O-O bond remains critical for efficient H 2 O 2 activation. Herein, the high-loading Fe SACs (FeN 1 C 2 /C 2 N, 7.2 wt%) is designed via in-situ carbon defect engineering, which breaks the symmetric electronic structure through the nonplanar asymmetric coordination of Fe. DFT calculations and characterizations reveal that compared to the planar symmetric Fe-N 2 structure, N 1 -Fe-C 2 coordination modifies d-p orbital hybridization, inducing the spin state of Fe from low-spin (LS, t 2g : ↑↓ , ↑↓ , ↑↓ ; e g : _, _, _) to high-spin (HS, t 2g : ↑↓ , ↑ , ↑ ; e g : ↑ , ↑ ; _). The HS state weakens the coupling between *H 2 O 2 and Fe 3 d orbitals, promoting H 2 O 2 decomposition into abundant •OH, further achieving electron-rich pollutant Sulfamerazine (SMR) degradation with the rate constant of k obs =0.3308 min -1 . Additionally, such nonplanar asymmetric coordination releases the N atoms adjacent to the Fe sites, allowing them to form electron-transfer channel with SMR, which establishes nonradical electron transfer pathway (ETP). Pollutant pre-adsorption enables •OH to attack the target in situ along an ultrashort pathway, resulting in an efficient ETP-assisted radical oxidation mechanism. Overall, this work provides new insights into SACs design and a novel perspective for Fenton-like systems application.
Rongming Cai,Mingzi Sun,Fei Yang,Min Ju,Yanpeng Chen,M. Danny Gu,Bolong Huang,Shihe Yang
Summary By leveraging a Cu(OH)F precursor, we construct a disk-like Cu(I)/Cu(0) interface model (P-Cu x /Cu 2 OF) composed of F-stabilized Cu(I) shell and Cu(0) core by one-step pulsed potential conversion. The interfacial region is shown to facilitate ethanol formation, guaranteeing a high FE(C 2+ ) of up to 80.2%. Tuning the Cu(I)/Cu(0) ratio enhances the ethanol yield by 18.5-fold over pure P-Cu, with the corresponding partial current density (j ethanol ) reaching up to 128 mA/cm 2 . This is enabled by a 3.6-fold boost in selectivity for the ethanol product (35.4%) and an overall 7.8-fold boost in activity ( j C 2 + up to 288 mA/cm 2 ). The interactions between P-Cu and Cu 2 OF upshift the d-band center of Cu sites on the interface region, which is critical to asymmetrical C-C coupling to form OCCOH∗, concurrent with a lowered energy barrier for ethanol formation. On the other hand, the ethylene-forming symmetrical C-C coupling occurs primarily on P-Cu away from the Cu(I)/Cu(0) interface.
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