Selective electrochemical hydrogenation of nitrobenzene to aniline coupled with efficient 5-hydroxymethylfurfural oxidation in aqueous electrolyte using a broccoli-like CuNi catalyst

Abstract

Selective electrochemical hydrogenation of nitrobenzene (NB) to aniline (AN) remains a huge challenge, and it is highly imperative to develop efficient and nonprecious electrocatalysts with superior stability. Herein, an earth-abundant Cu60Ni40 electrocatalyst is prepared by a simple galvanostatic deposition approach, which endows splendid electrocatalytic activity and robust stability in the nitrobenzene electroreduction with AN selectivity of ∼100 %. In-situ attuned total reflection Fourier transform infrared spectroscopy (ATR-FTIR) monitors the intermediates to disclose the reaction pathway. It mainly follows the direct route to AN instead of condensation route to azoxybenzene (AOB). Density functional theory (DFT) calculations confirm that the adsorption configuration and capability towards NB are effectively regulated owing to the synergy of bimetal catalysts and the optimized adsorption of H* facilitates the proton-coupled electrochemical reduction process, yielding AN with high selectivity. In addition, the two-electrode electrolyzer (CuNi NTs||CuNi) is successfully assembled to reduce NB to AN at the cathode and concurrently oxidize biomass platform molecule 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic (FDCA) at the anode with both yield of ∼100 %, demonstrating improved energy utilization efficiency. These findings might prove the way for rational design of non-precious and highly durable electrocatalysts for co-electrolysis systems to produce high-value added chemicals without carbon emission.