Al-Incorporated Cobalt-Layered Double Hydroxides for Enhanced Oxygen Evolution through Morphology and Electronic Structure Regulation.

ABSTRACT

Layered double hydroxides (LDHs) are promising electrocatalytic materials for the oxygen evolution reaction (OER) due to their tunable composition and low cost. Here, we construct ultrathin Al-incorporated Co LDH nanosheets on carbon cloth (CC) by a facile hydrothermal strategy. Compared to Co LDH/CC, the optimized Co2Al1 LDH/CC displays significantly improved OER performance, characterized by low overpotentials of only 171 and 200 mV to reach current densities of 10 mA cm-2 in alkaline and neutral media, respectively, as well as good stability over an extended period. The introduced Al3+ and CC support play a synergistic role in steering the morphology of Co2Al1 LDH/CC while also increasing the electrochemical active sites. X-ray absorption fine spectra (XAFS) analyses uncover the critical role of Al in regulating the coordination environment of Co atoms, with evidence affording highly active Co oxidation states. Moreover, density functional theory (DFT) calculations confirmed that the Al3+ incorporated into Co LDH/CC can efficaciously modulate the electronic density of states of the d-band center of Co atoms, optimize the Gibbs free energies of intermediates toward OER, and thus accelerate the O2 evolution rate.