Synergistic Electronic and Pore Structure Modulation in Open Carbon Nanocages Enabling Efficient Electrocatalytic Production of H₂O₂ in Acidic Medium

Abstract

Electrochemical synthesis of hydrogen peroxide (H2O2) through 2e– oxygen reduction reaction is an effective approach to replace anthraquinone process. However, most reported electrocatalysts work effectively in alkaline medium in which H2O2 will easily decompose into water. It is still of great challenge to develop cost‐effective electrocatalysts with high activity and selectivity for electrocatalytic H2O2 production in acidic media. Herein, it is first theoretically demonstrated that the adsorption energy of OOH* intermediate on carbon can be optimized by embedding Co nanoparticles (Co NPs) and tuning oxygen‐containing functional groups, ensuring high activity and selectivity. Guided by density functional theory calculations, highly porous open carbon nanocages with embedded Co NPs are designed and synthesized by template‐engaged method. The pyrolysis temperature can effectively modulate the electronic and pore structure of carbon nanocages. Impressively, the optimized carbon nanocages synthesized at 700 °C (P‐Co@C‐700) with highest percentage of –C–O–C group and defects, largest specific surface area (1351 m2 g–1), and mesoporous structure exhibit high selectivity up to 94% toward H2O2 production in 0.1 m HClO4. Furthermore, the P‐Co@C‐700 nanocages display promising application for efficient electro‐Fenton degradation of model organic pollutant.

Toward More Efficient Carbon-Based Electrocatalysts for Hydrogen Peroxide Synthesis: Roles of Cobalt and Carbon Defects in Two-Electron ORR Catalysis

“…To probe the chemical state of other elements, X-ray photoelectron spectroscopy (XPS) analyses were collected (Figure D–F). The C 1s spectrum (Figure D) was deconvoluted into components at 284.5, 285.1, 286.06, 286.8, 288.9, and 291.1 eV, which were associated with CC, C–C, C–N/C-O, CN/CO, COO, and π–π* transitions, respectively. ,− The C 1s spectrum of N/O–C was similar to that of Co–N/O-C-0.9 wt %, with the similarity of the two samples also evident in C K-edge XAS data (Figure G). The peak around 284.7 eV is assigned to a 1s-π* transition involving sp 2 CC.…”

“…N K-edge XAS confirmed the presence of various N species in N/O–C, again with less nitrogen in Co–N/O-C-0.9 wt % (Figure S9). The O 1s XPS spectra (Figure F) showed peaks for Co–O (530.0 eV), CO (531.0 eV), C–O–C (532.3 eV), OC–O (533.3 eV), COOH/C–OH (534.2 eV), and adsorbed H 2 O/O 2 (536.8 eV). ,,, For Co–N/O-C-0.9 wt %, the relative oxygen speciation was C–O–C (35.0%), CO (10.7%), OC–O (21.5%), and COOH/C–OH (13.39%). For N/O–C, the corresponding values were 15.15%, 27.20%, 24.39%, and 12.66%, respectively.…”

Mesoporous carbon-based materials and their applications as non-precious metal electrocatalysts in the oxygen reduction reaction

“…On the other hand, it appears that the addition of oxygenated species, for example to give Co-O-C, favours high selectivity for the two electron transfer reaction, as displayed in Fig. 6 [178,217]. Indeed, it has been shown using computational studies, that a lower energy barrier exists for the adsorption of *OOH on COOH-terminated carbon.…”

“…Several nanoparticles and nanostructures have been successfully immobilised within MC to give impressive ORR activity and these include a number of iron-based nanostructures, including iron nanoparticles [159], Fe 3 O 4 [160,161] , Fe 2 O 3 [162], Fe/Fe 2 O 3 [163], FeCo [164], CoFe 2 O 4 [165,166], Fe 1− x S [167], Fe 3 C [168][169][170][171], FeS [172], and Fe 2 P [173,174] nanostructures. Similarly, a number of cobalt-based nanostructures have been employed, such as Co nanoparticles [175][176][177][178][179][180], single-atom-like Co with Co nanoparticles [181], CoO [182][183][184], Co/CoO [185], Co 3 O 4 [186,187], CoP [153,188], CoCu Fig. 5.…”

Carbon nanomaterial-based membranes for water and wastewater treatment under electrochemical assistance

“…201,237 Researches have demonstrated that they can achieve the simultaneous dehalogenation and oxidation of halide. 237 Because oxygen can be cathodically reduced into H 2 O 2 on carbonaceous catalysts, [238][239][240] the integration of electro-Fenton and membrane separation has drawn increasing attention to remove various organic pollutants (Fig. 6a), such as dye molecules, 241,242 persistent oxalate, 170,171 and antibiotics.…”