Intercalation and elimination of carbonate ions of NiCo layered double hydroxide for enhanced oxygen evolution catalysis

The developments of inexpensive and efficient oxygen evolution reaction (OER) electro-catalysts without noble metals are very critical for energy conversion and storage systems. In this work, a series of NiCo-layered double hydroxide (NiCo-LDH) and NiCo oxides using co-precipitation and thermal treatment method have been successfully synthesized. Structural characterizations have been investigated by X-ray powder diffraction (XRD), Field emission scanning electron microscope (FE-SEM) equipped with energy-dispersive Xray mapping technology (EDS), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy respectively (XPS). By intercalating and eliminating CO33- an- ions in the layers of bulk NiCo-layered double hydroxide (NiCo-LDH), the as-present catalyst (NiCo-CH) exhibit remarkable advantages for OER performance, including porous nanostructures, high surface area, high content of Ni3+ and Co2+ on the surface and abundant active sites. With these favorable features, NiCo-CH shows a much better OER performance than that of other catalysts and commercial Pt/C, which has a low onset potential (1.51 V), a low overpotential (343 mV at 10mA/cm(-2)) and a small Tafel slope (66mWdec(-1)). Our work presents an effective strategy to controllably design and synthesize NiCo-LDH electrocatalysts with optimizable OER performances. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.