Enhanced Fe(Iii)/Fe(Ii) Circulation and H2o2 Utilization in an Efficient Solid–Liquid-Interfacial Fenton-Like Reaction Over the Sulfur Quantum Dots Cocatalyst at Neutral Ph

Abstract

Classical Fenton oxidation has been extensively applied in environmental remediation. However, the bottlenecks including sluggish Fe(III)/Fe(II) cycling, low H2O2 utilization efficiency and narrow pH application range restrict its practical application. Herein, we found sulfur quantum dots (SQDs) as a stable and green cocatalyst to surmount the bottlenecks of Fenton oxidation. In the SQDs/Fe(III)/H2O2 system, despite Fe(III) being slightly reduced into Fe(II) through SQDs, the SQDs can function as an electron mediator between H2O2 and complexed Fe(III) to boost the electron transfer from H2O2 to Fe(III) species, significantly ensuring catalytic stability for practical applications in strongly oxidative scenarios. Unlike traditional electron sacrificial agents, H2O2 was applied as a green electron donor to strengthen Fenton oxidation during the catalysis of SQDs. The complexation of SQDs with Fe(III) species (i.e., Fe(OH)2+ and Fe(OH)4–) by surface sulfonyl/sulfonic groups obviously elevated the oxidation potential of Fe(III) species with increasing pH (3.0–9.0), thus facilitating Fe(III) withdrawing electrons from H2O2 to realize efficient Fe(III)/Fe(II) circulation. The accelerated Fe(II) generation induced efficient activation and utilization of H2O2 as well as potent generation of •OH for effectively oxidizing various pollutants across a wide pH range. The excellent catalytic activity, pH adaptability and stability of SQDs demonstrated their superb practicality for the treatment of real wastewater and provided an effective and promising strategy for wastewater decontamination and environmental remediation.

Keywords: Sulfur quantum dots, Fenton-like catalysis, Fe(III)/Fe(II) circulation, H2O2 utilization efficiency, pH adaptability, Wastewater decontamination