Cerium Phosphate as a Novel Cocatalyst Promoting NiCo₂O₄ Nanowire Arrays for Efficient and Robust Electrocatalytic Oxygen Evolution

Incorporating electrocatalysts with rare earth elements has attracted increasing attention in electrocatalysis because of its effective modulation of their chemical and electronic structures for enhanced catalytic hydrogen and oxygen evolution reactions. Herein, cerium phosphate (CePO 4 ) is demonstrated to be a novel cocatalyst that significantly enhances the OER performance of NiCo 2 O 4 nanowire arrays on Ni foam. The high durability of OER performance over 1000 h and the low overpotential of 281 mV required to maintain a catalytic current density of 20 mA cm –2 can be attributed to the synergetic effect between CePO 4 and NiCo 2 O 4 . Explicitly, CePO 4 as a cocatalyst efficiently tunes the surface states of NiCo 2 O 4 and facilitates water adsorption and the conversion of intermediates, leading to a substantial OER performance enhancement. All results exhibit the potential of integrating CePO 4 into NiCo 2 O 4 to improve the water oxidation activity of NiCo 2 O 4 and illustrate wide domains of application by combining rare earth elements into electrocatalysts.