Electrooxidation of 5-Hydroxymethylfurfural via Ni₂P-Ni₃Se₄ Heterostructure Nanosheet Arrays

The electrooxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) has been deeply investigated. However, developing a durable electrocatalyst for fast production of FDCA at low potentials remains a challenge. Herein, we report Ni₂P-Ni₃Se₄ heterostructure nanosheet arrays as efficient electrocatalysts for HMF electrooxidation. These nanosheet arrays were synthesized via an in situ deep eutectic solvent etching approach, followed by phosphorization and a selenization process. The optimal Ni₂P-Ni₃Se₄ electrocatalyst could achieve 99.1% FDCA selectivity, 98.9% Faradaic efficiency, and 100% HMF conversion at 1.38 V (reversible hydrogen electrode) within 1.6 h. Density functional theory calculations demonstrate that apparent charge redistribution occurs at the Ni₂P/Ni₃Se₄ heterointerface, which greatly enhances HMF adsorption and consequently modulates the catalytic performance. In situ Raman spectroscopy technology confirms that NiOOH is the main active species during HMF electrooxidation. This work provides a significant strategy to develop robust heterogeneous electrocatalyst for HMF electrooxidation and beyond.