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.