Polyoxometalate intercalated NiFe layered double hydroxides for advanced water oxidation

Abstract

Exploring high efficient and cost-effective electrocatalysts for oxygen evolution reaction is a determination step towards sustainable green energy applications. Polyoxometalates and layered double hydroxide materials are suggested to be potential catalyst materials; however, those electrocatalytic behaviors are greatly inferior to the state-of-the-art OER electrocatalysts (RuO2 and IrO2). In this work, we employ a self-assembly approach in which polyoxometalate anions are successfully intercalated into NiFe layered double hydroxide. Upon analysis of the composition, the elemental valence state and the infrared spectrum, it confirms that the intercalated polyoxometalate anions in the layers of NiFe layered double hydroxide are in the format of PW12O403−. Even though the partial anions in the as-prepared intercalation NiFe layered double hydroxide are only polyoxometalate anions, its electrochemical performance surpasses the counterpart precursor NiFe layered double hydroxide (NO3−) in many aspects, such as turnover frequencies, overpotentials, kinetics, and stability. The introduction of polyoxometalate anions can optimize the local electronic structure which enhances the charge transport capacity of NiFe layered double hydroxide as well as alter the adsorption/desorption nature of the intermediates during the catalysis process. This work provides a new strategy to boost the OER activity of layered double hydroxide-based electrocatalysts.