Density Functional Theory Investigation into the Effects of Dissolved Organic Matter on H₂O₂ Activation over α-Fe₂O₃ (001) Surfaces

Abstract

The heterogeneous Fenton process is one of the efficient methods for wastewater treatment, and the effects of dissolved organic matter (DOM) when treating actual wastewaters are anticipated. However, the impact of DOM on H2O2 activation is not clearly understood yet. In this work, the α-Fe2O3 (001) surfaces are chosen as the model materials and the effects of the major functional groups in DOM on H2O2 activation are systematically investigated using density functional theory simulations. First, the adsorption and activation of H2O2 on the surfaces are simulated, confirming the superior catalytic properties of the Fe sites on the α-Fe2O3 (001) surface with an oxygen vacancy. Then, the adsorption configurations with various DOM functional group representations are obtained. Phenol, carboxyl, amide, and quinone groups adsorb more strongly on the surfaces than H2O2, while the hydroxyl and aldehyde groups show weaker adsorption. Finally, the coadsorption of the DOM molecules and H2O2 is simulated and the influences on the activation barrier of H2O2 are studied. For the pristine surface, the intermolecular interactions can promote or inhibit the H2O2 cleavage with some DOM molecules. However, for the surface with an oxygen vacancy, due to the competition for adsorption sites, some DOM functional groups are found to substitute the H2O2 at the most reactive Fe site, thus inhibiting its activation. The direct interactions between the DOM molecules and H2O2 do not significantly affect H2O2 activation. This work reveals the various effects of DOM on H2O2 activation and contributes to the application of the heterogeneous Fenton technology.

Reactive oxygen species on transition metal-based catalysts for sustainable environmental applications

“…For example, Density Functional Theory (DFT) calculations show that the adsorption of H 2 O 2 is stronger on the deficient α-Fe 2 O 3 (001) surface than on the pristine surface. 116 The energy barrier of activation and the O–O bond length at the transition state are 3.65 kJ mol −1 and 1.60 Å for H 2 O 2 adsorbed on the α-Fe 2 O 3 surface with OVs, but 44.89 kJ mol −1 and 1.75 Å on the pristine α-Fe 2 O 3 surface. Analogously, introducing S vacancies (SVs) in Fe 3 S 4 (FS-100) creates strong peroxidase-like activity not available from SV-poor Fe 3 S 4 (FS-0), which can be attributed to the efficient adsorption of H 2 O 2 and its subsequent decomposition to HO˙ at the SVs of Fe 3 S 4 (Fig.…”

“…For example, Density Functional Theory (DFT) calculations show that the adsorption of H 2 O 2 is stronger on the decient a-Fe 2 O 3 (001) surface than on the pristine surface. 116 The energy barrier of activation and the O-O bond length at the transition state are 3.65 kJ mol À1 and 1.60 Å for H 2 O 2 adsorbed on the a-Fe 2 O 3 surface with OVs, but 44.89 kJ mol À1 and 1.75…”

NO Oxidation Using H2O2 at a Single-Atom Iron Catalyst

“…10 Gong et al exploited four Fe active sites on the surface of α-Fe 2 O 3 (001) to probe the impact of various activation methods and dissolved organic substances (DOM) on the energy barriers of H 2 O 2 activation to *OH (44.89 kJ/mol). 11 Li et al explored the dissociation of H 2 O 2 on hexagonal boron nitride and obtained seven possible species, among which the energy barrier of H 2 O 2 activation to *OH was 86.6 kcal/mol. 12 However, the above-mentioned oxidants have insufficient catalytic activity for H 2 O 2 and poor selective stability due to their many active sites and complex activation mechanisms, posing a major obstacle to the large-scale application of advanced oxidation methods for pollutant removal.…”

“…(71.12 kJ/mol) . Gong et al exploited four Fe active sites on the surface of α-Fe 2 O 3 (001) to probe the impact of various activation methods and dissolved organic substances (DOM) on the energy barriers of H 2 O 2 activation to *OH (44.89 kJ/mol) . Li et al explored the dissociation of H 2 O 2 on hexagonal boron nitride and obtained seven possible species, among which the energy barrier of H 2 O 2 activation to *OH was 86.6 kcal/mol .…”

Design of single-atom catalysts for NO oxidation using OH radicals

“…The OH radicals have been proven to be effective in removing many pollutants. For instance, Gong et al 25 generally investigated the effect of dissolved organic substances (DOMs) on the activation of H 2 O 2 on the surface of α-Fe 2 O 3 (001) using density functional theory, demonstrating the superior catalytic performance of its Fe site. Through the co-adsorption analysis of DOM molecules and H 2 O 2 , it was found that the active site can effectively promote the activation of H 2 O 2 to generate OH radicals, which can better oxidize DOM molecules.…”