Boosting electrochemical oxygen reduction to hydrogen peroxide coupled with organic oxidation

Abstract

The electrochemical oxygen reduction reaction (ORR) to produce hydrogen peroxide (H₂O₂) is appealing due to its sustainability. However, its efficiency is compromised by the competing 4e⁻ ORR pathway. In this work, we report a hierarchical carbon nanosheet array electrode with a single-atom Ni catalyst synthesized using organic molecule-intercalated layered double hydroxides as precursors. The electrode exhibits excellent 2e⁻ ORR performance under alkaline conditions and achieves H₂O₂ yield rates of 0.73 mol g_cat⁻¹ h⁻¹ in the H-cell and 5.48 mol g_cat⁻¹ h⁻¹ in the flow cell, outperforming most reported catalysts. The experimental results show that the Ni atoms selectively adsorb O₂, while carbon nanosheets generate reactive hydrogen species, synergistically enhancing H₂O₂ production. Furthermore, a coupling reaction system integrating the 2e⁻ ORR with ethylene glycol oxidation significantly enhances H₂O₂ yield rate to 7.30 mol g_cat⁻¹ h⁻¹ while producing valuable glycolic acid. Moreover, we convert alkaline electrolyte containing H₂O₂ directly into the downstream product sodium perborate to reduce the separation cost further. Techno-economic analysis validates the economic viability of this system.

Electrochemical oxygen reduction is a promising method for H₂O₂ production but suffers from poor activity and low yield. In this work, the authors present Ni single atom catalyst for efficient H₂O₂ production which is further coupled with organic oxidation reaction to enhance the economic feasibility of the system.