Electrosynthesis of Hydrogen Peroxide through Selective Oxygen Reduction: A Carbon Innovation from Active Site Engineering to Device Design

Abstract

Electrochemical synthesis of hydrogen peroxide (H2O2) through the selective oxygen reduction reaction (ORR) offers a promising alternative to the energy‐intensive anthraquinone method, while its success relies largely on the development of efficient electrocatalyst. Currently, carbon‐based materials (CMs) are the most widely studied electrocatalysts for electrosynthesis of H2O2 via ORR due to their low cost, earth abundance, and tunable catalytic properties. To achieve a high 2e− ORR selectivity, great progress is made in promoting the performance of carbon‐based electrocatalysts and unveiling their underlying catalytic mechanisms. Here, a comprehensive review in the field is presented by summarizing the recent advances in CMs for H2O2 production, focusing on the design, fabrication, and mechanism investigations over the catalytic active moieties, where an enhancement effect of defect engineering or heteroatom doping on H2O2 selectivity is discussed thoroughly. Particularly, the influence of functional groups on CMs for a 2e−‐pathway is highlighted. Further, for commercial perspectives, the significance of reactor design for decentralized H2O2 production is emphasized, bridging the gap between intrinsic catalytic properties and apparent productivity in electrochemical devices. Finally, major challenges and opportunities for the practical electrosynthesis of H2O2 and future research directions are proposed.

Emerging Two-Dimensional Carbonaceous Materials for Electrocatalytic Energy Conversions: Rational Design of Active Structures through High-Temperature Chemistry

“…Thus, fine operating the pyrolysis conditions alters the N active motifs in 2D carbon catalysts and thereby allows tuning the ORR process between the 4e – and 2e – pathway. For example, early mechanistic analysis of the electrochemical ORR process revealed a lower and uneven number of transferred electrons on several N-doped carbon electrocatalysts, suggesting a mixed reaction pathway ( e.g ., 2e – + 4e – ) that might be originated from the different activity/selectivity upon varying C–N substructures. , Inspired by such phenomenon, Fellinger and co-workers reported the pyrolysis-assisted fabrication of mesoporous N-doped carbon (BMP-800 and meso-BMP-800) from the ionic liquid ( N -butyl-3-methylpyridinium dicyanamide, BMP-dca) . The N-enriched ionic liquid endows the catalysts with a high amount of structurally integrated N dopants, which provided the carbon electrocatalyst with a high, unusual H 2 O 2 selectivity during the acidic ORR process (Figure a–c).…”

“…Nevertheless, despite some progress, the possible roles of oxygen termination in electrocatalysis have not been revisited until very recently, especially for oxygen catalysis . Notably, recent studies have highlighted the long-ignored role of surface oxygen functionalities in selective O 2 reduction process, aiming to resolve the discrepancy in the experimentally observed ORR performances over the same types of CMs, especially regarding their H 2 O 2 selectivity . On the other hand, the cost-effectiveness and simplicity of the involved synthesis procedure of O-modified carbon composites have spurred the exploration of these CMs as efficient electrocatalysts.…”

“…97 Notably, recent studies have highlighted the long-ignored role of surface oxygen functionalities in selective O 2 reduction process, aiming to resolve the discrepancy in the experimentally observed ORR performances over the same types of CMs, especially regarding their H 2 O 2 selectivity. 62 On the other hand, the cost-effectiveness and simplicity of the involved synthesis procedure of O-modified carbon composites have spurred the exploration of these CMs as efficient electrocatalysts. We observe an increasing research interest in controlling the ORR selectivity through fine tailoring the types of oxygen functional groups on CMs.…”

DFT Understanding of the Oxygen Reduction to Hydrogen Peroxide on Graphene Modified by Oxygen Functional Groups

“…Although the catalytic performances of these carbonaceous materials with oxygen functional groups have been improved compared with the pristine ones, there is still room to enhance the performance, especially in catalytic activities. 9,15 However, the ORR mechanism on carbonaceous materials with oxygen functional groups has not been explored, limiting the research directions for further modification of these materials.…”

“…These pioneering works demonstrate that introducing oxygen functional groups into carbon-based materials improves the catalytic performance from that of pristine materials, motivating the development of carbonaceous electrocatalysts for the ORR. Although the catalytic performances of these carbonaceous materials with oxygen functional groups have been improved compared with the pristine ones, there is still room to enhance the performance, especially in catalytic activities. , However, the ORR mechanism on carbonaceous materials with oxygen functional groups has not been explored, limiting the research directions for further modification of these materials.…”