Highly Efficient Electrochemical Synthesis of Hydrogen Peroxide (H₂O₂) Enabled by Amino Acid Glycine-Derived Metal-Free Nitrogen-Doped Ordered Mesoporous Carbon

Abstract

Electrocatalytic partial oxygen reduction has been considered a more sustainable approach to the synthesis of hydrogen peroxide (H2O2), as compared with current industrial anthraquinone processes. One key research need is to explore low-cost active electrocatalysts. Here, we report a facile, solvent-free method to synthesize a metal-free nitrogen-doped ordered mesoporous carbon (N-OMC) by in situ transforming of glycine (carbon and nitrogen precursors) in the mesoporous SiO2 template (KIT-6) followed by subsequent thermal treatment at different temperatures. Among all samples, the catalyst treated at 800 °C (N-OMC-800), the nitrogen-rich carbon, exhibits outstanding structural properties and porosity, showing the dominant formation of pyrrolic-N and graphitic-N. With combined improved structural properties with the optimal ratio of N-pyrrolic/N-graphitic, P/G carbon provided an outstanding electrocatalytic activity, promoting H2O2 with high selectivity and production rate in alkaline mediums. The N-OMC-800 can achieve a faradaic efficiency (FE) of ∼100% to H2O2 at (0.6 VRHE to 0.4 VRHE) in a H-cell containing 0.1 M KOH. Furthermore, its bulk H2O2 electrosynthesis in our self-designed flow cell confirmed its practical capability by showing a remarkable H2O2 production rate of 9.43 mol gcat–1 h–1 at 0.35 VRHE and maintaining nearly 100% FE at the cathode potential of 0.6 VRHE for 12 h without any degradation.

Recent progress in electrocatalytic selectivity in heterogeneous electro-Fenton processes

“…−1 ·h −1 at 0.35 V vs. RHE without any degradation was achieved. 62 Based on the XPS and electrochemical analyses, Zhang et al revealed that the content of pyrrolic-N in the N-doped carbon materials delivered a positive effect on the 2e − ORR activity. When the cathode contains more pyrrolic-N, a better 2e − ORR selectivity is achieved in the alkaline medium.…”

Hierarchical N-Doped Co/Carbon Heterostructures with Tunable Selectivity for H2O2 Production from Air

“…Thence, transition-metal nanoparticles loaded on carbon-based materials have emerged as promising catalysts and have been paid more attention . Moreover, the introduction of heteroatoms, such as nitrogen-doped graphene, can distinctly alter the surface electronic structure of the active sites. − Regulating the electronic structure of active sites is an effective strategy in the electrochemical O 2 reduction reaction, which can be regarded as an inherent driving force significantly enhancing the chemisorption of targeted O 2 molecules . The existence of Mott–Schottky interface in transition-metal nanoparticles loaded with nitrogen-doped graphene has been proven, encouraging spontaneous charge transfer due to difference in their Fermi level and forming a special space–charge region. − Metallic nanoparticles (NPs) with a higher flat band potential lead to metal NPs becoming positively charged, which is favorable for O 2 dissociation and activation .…”

Lewis Acid Site Al-Promoted CoAl2O4/CoO Electrocatalyst for Efficient Electrochemical Production of H2O2 toward On-Site Pollutant Degradation

“…It is well-known that the efficient synthesis of H 2 O 2 is the key to the degradation of pollutants. 3,4 The production of H 2 O 2 is mainly based on industrial anthraquinone processes and direct mixing reaction of H 2 and O 2 . 3−5 However, these methods have been shown to have high costs, serious pollution, and high transportation risk.…”

“…As an important chemical material, hydrogen peroxide (H 2 O 2 ) is widely used in bleaching, textile factories, chemical synthesis, medical disinfection, wastewater treatment, and semiconductor manufacturing. , Among them, in the field of wastewater treatment, on-site generation of H 2 O 2 is considered as an effective process to degrade various pollutants with high efficiency and cost effectiveness. It is well-known that the efficient synthesis of H 2 O 2 is the key to the degradation of pollutants. , The production of H 2 O 2 is mainly based on industrial anthraquinone processes and direct mixing reaction of H 2 and O 2 . − However, these methods have been shown to have high costs, serious pollution, and high transportation risk . Therefore, H 2 O 2 needs to be synthesized in an environmentally friendly, economical, and safe way .…”