Improved Performance of Nickel Boride by Phosphorus Doping as an Efficient Electrocatalyst for the Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-furandicarboxylic acid (FDCA), an important platform chemical for renewable polymer industry, is receiving increasing interest. In this study, nickel borides (NiBx) doped with different amounts of phosphorus were prepared by a simple method and applied to the electrocatalytic oxidation of HMF. It was found that the FDCA yield on P-doped NiBx (NiBx–Py) gradually improved first and then decreased with the increase of phosphorus content. When NiBx–P0.07 (nP/nNi = 0.07) is used as the electrocatalyst, the FDCA yield reached the maximum (90.6%) and Faradaic efficiency was 92.5% at the potential of 1.464 V (vs RHE). XPS results indicate that the P dopant made relative displacement of electrons from surface nickel happen and surface nickel hydroxide species increased, which has a beneficial effect on its electrocatalytic performance. Furthermore, appropriate phosphorus doping accelerated charge transmission capability of NiBx–Py and then improved its activity. NiBx–P0.07 also has good stability in the potentiostatic electrolysis of HMF.