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 (Co 3 O 4 @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 (Co 3 O 4 ) nanosheet arrays. The deposition cycle of FeO x on the CC strongly influences the in situ growth and distribution of Co 3 O 4 nanosheets and electronic conductivity of the electrocatalyst. Owing to the high accessible and electroactive areas and improved electrical conductivity, the free-standing electrode of Co 3 O 4 @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 Co 3 O 4 /CC (448 mV), and even commercial RuO 2 (380 mV). This design and optimization strategy shows a promising way to synthesize ideally designed catalytic architectures for application in energy storage and conversion.