Enabling high-efficiency ethanol oxidation on NiFe-LDH via deprotonation promotion and absorption inhibition

Abstract

Nucleophile oxidation reaction (NOR), represented by ethanol oxidation reaction (EOR), is a promising pathway to replace oxygen evolution reaction (OER). EOR can effectively reduce the driving voltage of hydrogen production in direct water splitting. In this work, large current and high efficiency of EOR on a Ni, Fe layered double hydroxide (NiFe-LDH) catalyst were simultaneously achieved by a facile fluorination strategy. F in NiFe-LDH can reduce the activation energy of the dehydrogenation reaction, thus promoting the deprotonation process of NiFe-LDH to achieve a lower EOR onset potential. It also weakens the absorption of OH− and nucleophile electrooxidation products on the surface of NiFe-LDH at a higher potential, achieving a high current density and EOR selectivity, according to density functional theory calculations. Based on our experiment results, the optimized fluorinated NiFe-LDH catalyst achieves a low potential of 1.386 V to deliver a 10 mA cm−2 EOR. Moreover, the Faraday efficiency is greater than 95%, with a current density ranging from 10 to 250 mA cm−2. This work provides a promising pathway for an efficient and cost-effective NOR catalyst design for economic hydrogen production.