Selective electrooxidation of 5-hydroxymethylfurfural at low working potentials promoted by 3D hierarchical Cu(OH) 2 @Ni 3 Co 1 -layered double hydroxide architecture with oxygen vacancies.

Selective electrooxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is of great significance in the manufacture of fine chemicals, liquid fuels, pharmaceuticals, plastics, etc. , but still suffers from the high potential input, resulting in high electricity consumption. Developing active, low-cost and stable electrocatalysts is crucial for this electrochemical reaction at low working potentials. Herein, a three-dimensional (3D) hierarchical Cu(OH) 2 @Ni 3 Co 1 -layered double hydroxide architecture with abundant oxygen vacancies (Vo) was synthesized by facile electrodeposition of Ni 3 Co 1 -LDH nanosheets on copper foam (CF) supported-Cu(OH) 2 nanorods (CF/Cu(OH) 2 @Ni 3 Co 1 -LDH) for the selective electrooxidation of HMF to FDCA. The 3D hierarchical architecture of the Cu(OH) 2 nanorod core loaded with Ni 3 Co 1 -LDH nanosheet shell facilitates the rapid transfer of charges and exposes more active sites. The synergistic effect of the core-shell nanoarray structure, atomic level dispersion of Ni and Co on LDH laminates, and rich Vo gives 98.12% conversion of HMF, 98.64% yield and 91.71% selectivity for FDCA at a low working potential of 1.0 V vs. RHE. In addition, CF/Cu(OH) 2 @Ni 3 Co 1 -LDH exhibits superior stability by maintaining 93.26% conversion of HMF, 93.65% yield and 91.57% selectivity of FDCA after eight successive cycles, showing the immense potential of utilizing electrochemical conversion for biomass.