A phase transformation-free redox couple mediated electrocatalytic oxygen evolution reaction

NiFe layered double hydroxide (NiFe-LDH), as a promising non-noble catalyst for oxygen evolution reaction (OER), suffers from the high OER barriers during Ni x Fe 1−x (OH) 2 /Ni x Fe 1−x OOH interconversion. To solve this problem, we highly dispersed the 2–3 nm CeO 2−x particles on single-layered NiFe-LDH to form CeO 2−x /NiFe-LDH heterostructure by a one-step co-precipitation method. CeO 2−x , as an electron acceptor, can extract electrons from Ni sites of NiFe-LDH via Ni-O-Ce electron exchange effect, thus achieving direct Ni 2+ /Ni 3+ electron transfer with no need of Ni x Fe 1−x (OH) 2 /Ni x Fe 1−x OOH phase transformation. As a result of efficient electron transfer by strong interface interactions between CeO 2−x and NiFe-LDH, the CeO 2−x /NiFe-LDH exhibits excellent OER performance with a low OER overpotential of 216 mV at 10 mA cm −2 and a Tafel slope of 74.1 mV dec − 1 . Our work provides a new strategy to improve the OER performances of NiFe-based materials. • Avoiding phase transformation of Ni x Fe 1−x (OH) 2 /Ni x Fe 1−x OOH during the Ni 2+ /Ni 3+ oxidation process to trigger OER on NiFe-LDH. • Ni 2+ /Ni 3+ oxidation can be mediated by the Ce 3+ /Ce 4+ redox couple in CeO 2−x rather than deprotonation in NiFe-LDH. • Providing a new strategy to improve the OER performances of NiFe-based materials.