Synthesis of H₂O₂ via 2e⁻ O₂ reduction or 2e⁻ H₂O oxidation has been widely acknowledged as promising alteratives to the energy-intensive anthraquinone processes. Herein, we report that the 2e⁻ O₂ reduction and 2e⁻ H₂O oxidation reactions, for the first time, can be efficiently promoted on CeO₂ (100) facets, while majority of previous CeO₂ materials are utilized overwhelmingly as catalyst substrates. Electrochemical measurements indicate that CeO₂ nanocubes (NCs) deliver very high H₂O₂ selectivity of 83% and faradic efficiency of 95.3% for 2e⁻ O₂ reduction. Its H₂O₂ yield rate at 0.5 V (vs. RHE) reaches 632 mmol g_cat⁻¹ h⁻¹, which exceeds the performance of facet-unspecified CeO₂ 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⁻ H₂O oxidation. When assembled into flow cell reactor, the CeO₂ NCs can obtain a total H₂O₂ 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.

通过 2e ^- O ₂还原或 2e ^- H ₂ O 氧化合成 H ₂ O ₂已被广泛认为是能源密集型蒽醌过程的有希望的替代品。在此，我们首次报道了 2e ^- O ₂还原和 2e ^- H _{2 O 氧化反应可以在 CeO 2} (100) 晶面上有效地促进，而之前的大多数 CeO ₂材料被压倒性地用作催化剂基材. 电化学测量表明，CeO ₂纳米立方体 (NC) 可提供非常高的 H ₂^{2e -} O ₂还原的O ₂选择性为 83%，法拉第效率为 95.3% 。其在 0.5 V 时的 H ₂ O ₂产率（与 RHE 相比）达到 632 mmol g _cat ^-1 h ^-1，超过了这项工作中未指定刻面的 CeO ₂纳米点 (NDs) 和许多贵金属或碳的性能以前文献中的基电催化剂。此外，它还显示出 66% 的 2e ^- H ₂ O 氧化效率。当组装到流通池反应器中时，CeO ₂ NCs 可以获得4.6 mol g _{cat的总 H 2} O _2产率。^-1 h ^-1，并在宽电压范围内管理稳定的法拉第效率 (> 85%)。^{我们的工作可能会激发对用于 2e -}氧电催化的稀土金属氧化物基材料的进一步研究。