Amine group ligand-modified hydrotalcite-like nano cobalt hydroxide for efficient oxygen evolution reaction

Abstract

The advancement of highly-efficient, non-noble metal electrocatalysts with high active sites for oxygen evolution reaction (OER) continues to face severe challenges. In this work, a new 3D flower-like α-Co(OH)2 catalyst with high Co–NH2 active sites (referred to as α-Co(OH)2–NH2) is prepared. The Co–NH2 active sites are formed through the interactions between Co2+ and –NH2 groups and exhibit higher electrocatalytic performance for OER in alkaline mediums, with a lower overpotential (300 mV at 10 mA cm−2), a flatter Tafel slope (75 mV dec−1) and a longer stability. Moreover, water splitting catalyzed by α-Co(OH)2–NH2 delivers 1.62 V to reach a current density of 10 mA cm−2. The mechanism studies show that the OER electrocatalytic activity is closely related to the content of –NH2. Density functional theory (DFT) calculations unveil that –NH2 groups can facilitate the formation of OH∗ on the α-Co(OH)2 surface and promote the desorption of O2∗ into O2(g).