Cluster-Level Heterostructure of PMo₁₂/Cu for Efficient and Selective Electrocatalytic Hydrogenation of High-Concentration 5-Hydroxymethylfurfural

Abstract

Electrochemical hydrogenation of aldehyde molecules, exemplified by 5-hydroxymethylfurfural (HMF), offers a sustainable approach for synthesizing higher value-added alcohols. However, severe coupling side reactions impede its practical implementation at high concentrations. In this work, a cluster-level heterostructure of a PMo₁₂/Cu catalyst is synthesized by loading Keggin-type phosphomolybdic acid (H₃PMo₁₂O₄₀, PMo₁₂) onto Cu nanowires. The catalyst exhibits high selectivity in electrocatalytic hydrogenation (ECH) of HMF to 2,5-bishydroxymethylfuran (BHMF) under an unprecedentedly high substrate concentration of 1.0 M. Under -0.3 V (vs RHE) with 1.0 M HMF, PMo₁₂/Cu shows a Faradaic efficiency as high as 98% with an excellent productivity of 4.35 mmol cm^-2 h^-1 toward BHMF, much higher than those on the pristine Cu nanowires. Mechanism studies and density functional theory calculations demonstrate that the heterostructural interface of PMo₁₂/Cu serves as an active reaction center for the ECH. The unique electronic properties and geometric structure promote the dissociative reduction of water molecules to generate H* and reduce HMF with a decreased reaction energy barrier, which is responsible for exceptional reactivity and selectivity.