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 gcat-1 h-1 in the H-cell and 5.48 mol gcat-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 gcat-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.