Modulation of Charge Trapping by Island‐like Single‐Atom Cobalt Catalyst for Enhanced Photo‐Fenton‐Like reaction

Abstract

Composites‐based photocatalysis relies on the interfacial electron transfer between the metallic cocatalyst and photosensitizer (the semiconductor) to realize spatial separation of charge carriers. Herein, an ingenious heterojunction between Co‐CN single atom catalysts (SACs) and g‐C3N4 is constructed for heterogeneous photo‐Fenton‐like reactions. Driven by built‐in electric field across the heterojunctions, the separation and migration of the photogenerated charge carriers is promoted, leading to the fast electron transfer from the g‐C3N4 to the Co‐CN SACs. Theoretical calculations and transient absorption spectroscopy reveal the modulated charge transfer and trapping in the SA‐Co‐CN/g‐C3N4 heterostructure, resulting in the remarkably enhanced generation of reactive oxygen species via peroxymonosulfate activation under light irradiation. This ingenious SA‐Co‐CN/g‐C3N4/PMS/vis system is efficient for the oxidation of various antibiotics with high removal efficiency (>98%), a wide operating pH range (pH 3–11) and excellent stability in long‐term operation. This study provides a new tactic for rational design of SACs‐based heterojunctions to bridge photocatalysis and heterogeneous catalysis, attaining superior photoredox activity via interfacial coupling.

Facilely Tuning the First-Shell Coordination Microenvironment in Iron Single-Atom for Fenton-like Chemistry toward Highly Efficient Wastewater Purification

“…Specifically, peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) have been recognized as an efficient way of treating recalcitrant organic pollutants from wastewater by generating robust reactive oxygen species (ROS). – Compared with the homogeneous catalytic processes initiated by transition metal ions (Fe 2+ , Co 2+ , and Cu 2+ ), heterogeneous Fenton catalytic processes have great advantages regarding catalyst recovery and catalytic stability. Especially, abundant carbon-supported transition metal–N–C catalysts (M–N–C: M = Fe, Co, Mn, and Cu) have gained considerable interest in PMS activation for generating numerous ROS [i.e., hydroxyl radicals ( • OH), sulfate radicals (SO 4 •– ), high-valent metal-oxo complexes, mediated electron transfer mechanisms, and singlet oxygen ( 1 O 2 )]. – Among them, 1 O 2 behaves as a versatile and universal oxidation species with a lifetime much longer than that of radicals in AOPs. , However, apparent drawbacks of traditional M–N–C catalysts such as the poor production of 1 O 2 , slow catalytic kinetics, and low metal utilization greatly restrict their application in actual wastewater treatment. Developing novel processes to efficiently produce potent reactive 1 O 2 is highly desired.…”

An Unlocked Two‐Dimensional Conductive Zn‐MOF on Polymeric Carbon Nitride for Photocatalytic H2O2 Production

“…However, until now, very few single‐atom sites have been reported as active centers for the photocatalytic O 2 reduction to H 2 O 2 [3] . This is most likely because many transition metal sites can decompose H 2 O 2 , [27,28] which could be accelerated by light irradiation, a process known as the photo‐Fenton reaction [29–31] . Therefore, the desirable active sites for the photocatalytic H 2 O 2 synthesis should be able to selectively reduce O 2 to H 2 O 2 upon receiving the photoelectrons while not decomposing H 2 O 2 under both dark and light conditions.…”

“…[3] This is most likely because many transition metal sites can decompose H 2 O 2 , [27,28] which could be accelerated by light irradiation, a process known as the photo-Fenton reaction. [29][30][31] Therefore, the desirable active sites for the photocatalytic H 2 O 2 synthesis should be able to selectively reduce O 2 to H 2 O 2 upon receiving the photoelectrons while not decomposing H 2 O 2 under both dark and light conditions. Nevertheless, this remains a significant challenge and requires innovative strategies.…”

Single Zn Atoms with Acetate‐Anion‐Enabled Asymmetric Coordination for Efficient H2O2 Photosynthesis

“…Some advanced single‐atom sites, such as the engineered Co−N 4 moieties, have been identified as efficient catalytic sites for the electrochemical O 2 reduction to H 2 O 2 , [14,22,23] but very few have been achieved for H 2 O 2 photosynthesis. This is because many transition metal sites can decompose H 2 O 2 , [24,25] especially under light irradiation conditions, which is known as the photo‐Fenton reaction [26–28] . Therefore, in parallel with the design of active sites capable of efficiently reducing O 2 to H 2 O 2 , it is also necessary and essential to consider the tolerance of H 2 O 2 to catalysts for the continuous production and stable storage of H 2 O 2 .…”