Two-dimensional metal–organic framework nanosheets for highly efficient electrocatalytic biomass 5-(hydroxymethyl)furfural (HMF) valorization

Abstract

To construct a green chemical synthesis system for a better future of human beings, the utilization of water as an oxygen source and electricity as the driving force for the oxygenation of biomass valorization is of great significance and essential. Here, we first investigated the possibility for 5-hydroxymethylfurfural (HMF) electrooxidation into 2,5-furandicarboxylic acid (FDCA) by Ni-based two-dimensional metal–organic frameworks (2D MOFs) as electrocatalysts. FDCA is a desirable alternative to fossil-based terephthalic acids for the production of environmentally friendly polymers. The as-prepared Co-doped 2D MOFs NiCoBDC (Ni²⁺, BDC = terephthalic acid) have a high FDCA yield of 99%, an excellent yield rate of 20.1 μmol cm⁻² h⁻¹ and a faradaic efficiency of 78.8% at 1.55 V vs. RHE, as performed in an electrolyte at pH 13, where the degradation of HMF was ignored. Benefitting from the accessible pores of HMF molecules, abundant exposed active sites and coupling effects between Ni and Co atoms, 2D NiCo-MOFs realized a high catalytic activity and a robust electrochemical durability. This work demonstrates 2D MOFs as promising electrocatalysts for highly efficient biomass valorization because of their porosity and rich active sites.