Elucidation and modulation of active sites in holey graphene electrocatalysts for H₂O₂ production

Abstract

Selective electrochemical oxygen reduction (ORR) toward a two-electron (2e À ) pathway is an eco-friendly alternative method for H 2 O 2 synthesis to replace the energy-intensive anthraquinone oxidation process. Carbon-based electrocatalysts (CBEs) show great potential for practical H 2 O 2 synthesis. However, their complex structures make it challenging to determine the nature of active sites and to precisely control them. Herein, we show that precise modulation of the chemistry and structures of holey graphene with edge sites enriched by oxygen-containing functional groups can facilitate 2e À ORR. These combined functionalities could improve ORR performance under various pH conditions, for example, resulting in an average of 95% H 2 O 2 selectivity, ~97% Faraday efficiency, high productivity of 2360 mol kg cat À1 h À1 in alkaline media. Density functional theory calculations on the oxygen functional groups at the edge sites revealed the most active site for 2e À ORR is a synergy between ether (C O C) and carbonyl (C O) functional groups with nearly zero overpotential.

CoSe2 supported single Pt site catalysts for hydrogen peroxide generation via two‐electron oxygen reduction

“…The sinusoidal ac perturbation of 0.56 V (vs. RHE) was used to obtain electrochemical impedance spectroscopy (EIS). As shown in Figure S4, two semicircles appear, which are attributed to the kinetic‐diffusion mixed control region 44 . Equivalent circuit fitting plots display that Pt 1 /CoSe 2 has low R 2 (331.6 Ω) and R 3 (415.5 Ω) values.…”

“…As shown in Figure S4, two semicircles appear, which are attributed to the kinetic-diffusion mixed control region. 44 Equivalent circuit fitting plots display that Pt 1 /CoSe 2 has low R 2 (331.6 Ω) and R 3 (415.5 Ω) values. The R 2 and R 3 for CoSe 2 are 430 and 1577 Ω, respectively.…”

Highly coordinative molecular cobalt–phthalocyanine electrocatalyst on an oxidized single-walled carbon nanotube for efficient hydrogen peroxide production

“…[1][2][3] It is also listed as a disinfectant against SAR-CoV-2, which is responsible for the COVID-19 pandemic. 4 Recently, the As a green and versatile oxidant, hydrogen peroxide (H 2 O 2 ) is produced via the energy-and waste-intensive anthraquinone oxidation (AO) method. Replacing the AO method by the electrochemical strategy of the two-electron oxygen reduction reaction (2e À ORR) has shown great prospects for economic and environmental benefits, which inspires our efforts to seek cost-effective and efficient electrocatalysts for potential industralization.…”

“…1–3 It is also listed as a disinfectant against SAR-CoV-2, which is responsible for the COVID-19 pandemic. 4 Recently, the worldwide demand for H 2 O 2 has remarkably increased, reaching an annual consumption exceeding US$ 4.0 billion and more than 95% of H 2 O 2 is generated through the anthraquinone technology. 5 However, this method involves a large amount of explosive hydrogen (H 2 ) as raw material and a complex separation process, 6 resulting in extra costs and safety concerns during the transportation, storage and utilization of bulk H 2 O 2 .…”

Defect-stabilized and oxygen-coordinated iron single-atom sites facilitate hydrogen peroxide electrosynthesis

“…[1][2][3] However, the current industrial H 2 O 2 production primarily relies on the anthraquinone process, which is associated with inherent drawbacks, especially high energy consumption, which hinders green and sustainable development. 4,5 Therefore, it is crucial to explore eco-friendly and efficient alternative approaches for H 2 O 2 production. The electrocatalytic oxygen reduction reaction (ORR), powered by renewable energy, provides an attractive H 2 O 2 synthetic strategy through a twoelectron reaction pathway.…”