Enhanced electrocatalytic performance for oxygen evolution reaction via active interfaces of Co₃O₄ arrays@FeO _x /Carbon cloth heterostructure by plasma-enhanced atomic layer deposition

Abstract Oxygen evolution reaction (OER) is a necessary procedure in various devices including water splitting and rechargeable metal-air batteries but required a higher potential to improve oxygen evolution efficiency due to its slow reaction kinetics. In order to solve this problem, a heterostructured electrocatalyst (Co3O4@FeO x /CC) is synthesized by deposition of iron oxides (FeO x ) on carbon cloth (CC) via plasma-enhanced atomic layer deposition, then growth of the cobalt oxide (Co3O4) nanosheet arrays. The deposition cycle of FeO x on the CC strongly influences the in situ growth and distribution of Co3O4 nanosheets and electronic conductivity of the electrocatalyst. Owing to the high accessible and electroactive areas and improved electrical conductivity, the free-standing electrode of Co3O4@FeO x /CC with 100 deposition cycles of FeO x exhibits excellent electrocatalytic performance for OER with a low overpotential of 314.0 mV at 10 mA cm−2 and a small Tafel slope of 29.2 mV dec−1 in alkaline solution, which is much better than that of Co3O4/CC (448 mV), and even commercial RuO2 (380 mV). This design and optimization strategy shows a promising way to synthesize ideally designed catalytic architectures for application in energy storage and conversion.