Design of hierarchical, three‐dimensional free‐standing single‐atom electrode for H₂O₂ production in acidic media

Abstract

Electrochemical reduction of molecular O2 to hydrogen peroxide (H2O2) offers a promising solution for water purification and environmental remediation. Here, we design a hierarchical free‐standing single‐Co‐atom (with Co–N4 coordination) electrode for oxygen reduction reaction (ORR) via a two‐electron pathway to make H2O2 in acidic media. The current density of the single‐Co‐atom electrode reached 51 mA/cm2 at 0.1 V vs reversible hydrogen electrode, lasting for more than 10 hours of continuous operation with H2O2 selectivity greater than 80%. Toward practical application, the single‐Co‐atom electrode was directly used to assemble an electrochemical cell to produce H2O2 at a rate of 676 mol/kgcat/h with a cell voltage of about 1.6 V.

Coordination Engineering of Single‐Atom Catalysts for the Oxygen Reduction Reaction: A Review

“…Besides, the catalyst's pores in the former works were larger than those in the latter work and thus the generated H 2 O 2 could more easily diffuse away from the electrode and avoid being further reduced to H 2 O. [ 157 ]…”

“…Besides, the catalyst's pores in the former works were larger than those in the latter work and thus the generated H 2 O 2 could more easily diffuse away from the electrode and avoid being further reduced to H 2 O. [157] Chen et al prepared well-defined Fe single-atom catalyst coordinated with pyrrole-N at room temperature, which showed excellent ORR performance, while other researchers believed that pyridine-N coordinated Fe single atom was the active site. [158] It is worth noting that different parameters (e.g., geometric configuration of the support, N-speciation, crystallinity, valence state of the center metal atom, etc.)…”

Electrochemical Oxygen Reduction to Hydrogen Peroxide via a Two‐Electron Transfer Pathway on Carbon‐Based Single‐Atom Catalysts

“…Some novel mechanisms could be introduced for designing an eligible electrode which could meet all the requirements. For example, the arrayed electrode can achieve rapid mass transfer and increase the overall efficiency of the reaction; [ 105 ] a superaerophilic surface modification could enrich the oxygen reactant and boost the current density. In general, SACs design for H 2 O 2 production device, based on the two‐electron ORR, is of great potential, but at the same time, more comprehensive exploration is still needed.…”

Recent progress in Co-N-C single-atom catalysts for the electrochemical oxygen reduction reaction

“…同时具有较大的比表面积以及更快的传质过程 [35] 笼 Co-PB-1(6) [36] . [37] . 由于具有较大的孔径, 反 应产生的 H2O2 能够及时导出, 避免被进一步还原成 H2O, 从而提高了 H2O2 的选择性.…”

“…Chen 等的研究也说明了较 大孔径利于过氧化氢的选择性, 相同的测试条件, 介 孔催化剂比微孔催化剂的 H2O2 产率更高 [38] . Co NP/CC、Co SA/CC 和 N-C/CC 的 H2O2 选择性对 比图 [37] . [37] .…”