Electrocatalytic conversion of nitrophenol pollutants to value-added products coupled with in situ separation via cation shuttling

Abstract

Electrochemical conversion of organic pollutants in wastewater (e.g., nitrophenol and its substituted compounds) into high-value-added products holds great promise for green chemistry and sustainable development. Here, we realized the metal-free electrocatalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at large current densities (∼300 mA cm⁻²) and a faradaic efficiency >72%, and the production rate reaches 0.64 mmol cm⁻² h⁻¹. To resolve the product–electrolyte separation problem, we designed a three-chamber flow cell with the cation-shuttling effect, which enables in situ purification of the product during electrochemical reactions at industrial-scale current densities. At 200 mA cm⁻², the reactor achieved ∼97% yield of the 4-AP product with a negligible electrolyte after 8 hours and there was almost no electrolyte present. We further directly used the obtained 4-AP solution and successfully synthesized the antipyretic medicine, paracetamol. This further validates the feasibility of our in situ separation method. This work demonstrates a novel electrocatalytic method for conversion of nitrophenol pollutants into important chemicals without the costly purification process.