In situ direct growth of flower-like hierarchical architecture of CoNi-layered double hydroxide on Ni foam as an efficient self-supported oxygen evolution electrocatalyst

Exploring economical, efficient and robust electrocatalysts toward the oxygen evolution reaction (OER) is one of the key issues in water splitting technology. Nanostructure engi-neering of electrocatalysts and hybridizing active species with a conductive support represent powerful strategies to enhance the electrocatalytic performance. Herein, we report a facile one-step solvothermal method to directly grow 3D CoNi-layered double hydroxide (LDH) flower-like architectures onto porous and conductive Ni foam (NF) sub-strate (denoted as CoNi-LDH(2:1)@NF hereafter). The flower-like hierarchical architecture of CoNi-LDHs with open configurations endows CoNi-LDH microflowers with sufficient accessible active sites and efficient mass diffusion paths. Moreover, the in situ direct growth manner ensures an intimate contact between the electroactive CoNi-LDHs and NF substrate and thus the charge transfer resistance is reduced. Consequently, the as-formed self-supported and binder-free electrode of CoNi-LDH(2:1)@NF exhibits an outstanding OER performance with a small overpotential of 283 mV at a relatively large current density of 50 mA cm(-2) and a remarkable long-term electrochemical durability in 0.1 M KOH solution, holding great promise in practical scale-up water electrolysis. The present study may open a new avenue to design and fabricate cost-effective and high-efficiency electrocatalysts for energy conversion applications. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.