Efficient overall 2e- oxygen electrolysis to H2O2 on CeO2 nanocubes

Synthesis of H 2 O 2 via 2e − O 2 reduction or 2e − H 2 O oxidation has been widely acknowledged as promising alteratives to the energy-intensive anthraquinone processes. Herein, we report that the 2e − O 2 reduction and 2e − H 2 O oxidation reactions, for the first time, can be efficiently promoted on CeO 2 (100) facets, while majority of previous CeO 2 materials are utilized overwhelmingly as catalyst substrates. Electrochemical measurements indicate that CeO 2 nanocubes (NCs) deliver very high H 2 O 2 selectivity of 83% and faradic efficiency of 95.3% for 2e − O 2 reduction. Its H 2 O 2 yield rate at 0.5 V (vs. RHE) reaches 632 mmol g cat −1 h −1 , which exceeds the performance of facet-unspecified CeO 2 nanodots (NDs) in this work and many noble metal- or carbon-based electrocatalysts in previous literatures. Furthermore, it also shows a high efficiency of 66% for 2e − H 2 O oxidation. When assembled into flow cell reactor, the CeO 2 NCs can obtain a total H 2 O 2 yield of 4.6 mol g cat. −1 h −1 , and manage stable faradic efficiency (> 85%) in wide voltage range. Our work may inspire further investigation of rare earth metal oxide-based materials for 2e − oxygen electrocatalysis.