The Intrinsic Nature of Persulfate Activation and N-Doping in Carbocatalysis

Abstract

Persulfates activation by carbon nanotubes (CNT) has been evidenced as nonradical systems for oxidation of organic pollutants. Peroxymonosulfate (PMS) and peroxydisulfate (PDS) possess discrepant atomic structures and redox potentials, while the nature of their distinct behaviors in carbocatalytic activation has not been investigated. Herein, we illustrated that the roles of nitrogen species in CNT-based persulfate systems are intrinsically different. In PMS activation mediated by nitrogen-doped CNT (N-CNT), surface chemical modification (N-doping) can profoundly promote the adsorption quantity of PMS, consequently elevate potential of derived nonradical N-CNT–PMS* complexes, and boost organic oxidation efficiency via an electron-transfer regime. In contrast, PDS adsorption was not enhanced upon incorporating N into CNT due to the limited equilibrium adsorption quantity of PDS, leading to a relatively lower oxidative potential of PDS/N-CNT system and a mediocre degradation rate. However, with equivalent persulfate adsorption on N-CNT at a low quantity, PDS/N-CNT exhibited a stronger oxidizing capacity than PMS/N-CNT because of the intrinsic higher redox potential of PDS than PMS. The oxidation rates of the two systems were in great linearity with the potentials of carbon–persulfate* complexes, suggesting N-CNT activation of PMS and PDS shared the similar electron-transfer oxidation mechanism. Therefore, this study provides new insights into the intrinsic roles of heteroatom doping in nanocarbons for persulfates activation and unveils the principles for a rational design of reaction-oriented carbocatalysts for persulfate-based advanced oxidation processes.

Construction of a Z-scheme g-C3N4/NBGO/BiVO4 heterostructure with visible-light driven photocatalytic degradation of tetracycline: efficiency, reaction pathway and mechanism

“…According to previous studies, pyridine N is positively correlated with the rate of oxidation due to the presence of pyridine N accelerating the pace of electron transport, and also enhancing the interaction between the catalyst and the contaminant. 37,38…”

Evolution of Singlet Oxygen by Activating Peroxydisulfate and Peroxymonosulfate: A Review

“…Free sulfate radicals were discovered to be responsible for phenol degradation in the same study [61]. However, some researchers also obtained a contrasting result that non-radical oxidation was dominant in the N-CNTs/PMS system [62]. Because of greater electronegativity, it was postulated that the doped N would enhance the interaction between the carbon atoms and PMS, and thus boost electron transfer.…”

Facile Synthesis of AgFeO2‐Decorated CaCO3 with Enhanced Catalytic Activity in Activation of Peroxymonosulfate for Efficient Degradation of Organic Pollutants

“…The initial solution pH is an important factor that affects the catalytic activity of heterogeneous catalysts. [ 41,42 ] As shown in Figure S2d, Supporting Information, complete degradation of RhB was achieved by the AgFeO 2 @CaCO 3 /PMS system over a wide pH range of 3.07–11.10, which covers the pH range of most industrial wastewater.…”