Ni, Co hydroxide triggers electrocatalytic production of high-purity benzoic acid over 400 mA cm−2

Abstract

With the increasingly prominent energy issues and environment problems, the electrocatalytic production of value-added fine chemicals by hybrid water electrolysis has shown much hope for replacing conventional energy-intensive chemical technology. However, the low current density caused by the competition of the oxygen evolution reaction at the anode has hindered the large-scale production of fine chemicals and H₂. Besides, the separation of products from the complicated electrolyte also remains a significant barrier. Herein, we present the integration of hybrid water electrolysis and conventional crystallization separation for the first time, achieving the electrocatalytic production and separation of benzoic acid without impurities. An amorphous nanosheet composed of Ni, Co hydroxide supported on Ni foam (A-Ni-Co-H/NF), with a large active area and low charge transfer resistance, is prepared for the first time and applied to catalyze the electrocatalytic benzyl alcohol oxidation reaction. A-Ni-Co-H/NF enables us to achieve an industrial-scale current density over 400 mA cm⁻² without the occurrence of the OER, and delivers ultrafast reaction kinetics. The yield of Ph-COOH is close to 100%, only spending 15 min at room temperature and atmosphere pressure. In situ Raman spectroscopy reveals that the as-made A-Ni-Co-H/NF catalyst features reversible structure evolution and recovery during the EBA reaction. The converted nickel oxyhydroxide containing Co species (Co-NiOOH) is confirmed as the real active species. This presents a novel electrocatalyst to achieve industrial-scale prodution for value-added chemicals and the novel integrated technology also provides guidance for the separation and collection of products during the electrocatalytic process.