Confining graphite-like carbon into ultrathin layered iron silicate for notably enhanced photo-Fenton catalysis: Mechanism insight and DFT calculation

The sluggish Fe(III)/Fe(II) conversion in the Fenton reaction strongly restrains the continuous generation of reactive oxygen species towards the oxidation of refractory pollutants. Herein, an ultrathin 2D/2D FeSi/GLC hybrid architecture is constructed by confining graphite-like carbon (GLC) in the layered-nanospace of Fe-bearing beidellite (FeSi) silicate for efficient photo-Fenton-like catalytic degradation of refractory pollutants. The 2D space-confinement effect of FeSi realizes the graphitization of carbonated glucose, in turn enhancing the electrical conductivity and visible-light harvesting ability of FeSi. By integrating the experimental and DFT calculation results, two pathways of Fe(II) recovery for enhancing Fenton oxidation are proposed: 1) GLC as electron-transfer channels significantly accelerates the photogenerated electrons transfer for Fe(II) reduction from Fe(III), as well as enhances electron shuttle from Fe(II) sites to H 2 O 2 , thus strongly promoting the cleavages of H 2 O 2 into •OH; 2) GLC mediates electron transfer from H 2 O 2 to Fe(III), boosting the regeneration of Fe(II) accompanied by •O 2 − production. As a demonstration, the hybrid FeSi 1.0 /C0.3–500 exhibits high-efficiency performance in photo-Fenton reaction with impressive catalytic activity (0.82 min −1 ), over 410 and 150 times faster than its analogue carbon-free system and commercial Fe 3 O 4 using phenol as the probe, respectively, accompanied by the mineralization of 74.4 % in 60 min. Additionally, the reaction system could remove 80 % of chemical oxygen demand (COD) from real coal chemical wastewater (200 mg·L −1 ) during 300 min of continuous operation. This study offers a new perspective for developing high-performance photo-Fenton catalysts, also confirms a promising practical application potential in industrial wastewater treatment.