A heterostructured electrocatalyst for the electrochemical valorization of 5-hydroxymethylfurfural coupled with the hydrogen evolution reaction

Abstract

The selective electrocatalytic oxidative upgradation of 5-hydroxymethylfurfural (HMF) is a promising approach to synthesize 2,5-furandicarboxylic acid (FDCA), an alternative bio-based precursor for the production of polymers. Coupling the anodic upgradation reaction with industrially important cathodic reactions such as hydrogen generation would increase the energy efficiency in electrochemical water splitting. Herein, we demonstrate the synthesis of a ternary heterostructure based on Ni_xS_y, MoS₂, and MoC supported on onion-like carbon for anodic HMF valorization. The heterostructured electrocatalyst efficiently catalyzes the selective oxidation of HMF to FDCA with 100% faradaic efficiency (FE) and yield. The complete conversion of HMF to FDCA is achieved in 65 min. The catalytic activity is evaluated in terms of FE and rate of production of FDCA (0.463 mmol_FDCA mmol_HMF⁻¹ h⁻¹ cm⁻²). The anodic valorization is achieved at 190 mV less positive potential with respect to the oxygen evolution reaction, supporting the strong electrocatalytic effect of the heterostructured catalyst. The availability of a large number of active sites due to abundant heterojunctions favors the facile electron transfer kinetics at a favorable potential. The catalyst is highly stable and reusable to deliver 100% yield even after 8 consecutive cycles without any compromise in the FE. The anodic oxidation of HMF is paired with the cathodic hydrogen evolution reaction using a cathode electrocatalyst. An observable negative shift (180 mV) in the cell voltage with respect to the oxygen evolution reaction is achieved with the paired electrocatalytic system, demonstrating the excellent activity of the catalyst.