Pd-Pt bimetallene for the energy-saving electrochemical hydrogenation of 5-hydroxymethylfurfural

Abstract

The electrochemical hydrogenation (ECH) of 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethylfuran (DHMF) represents a pivotal pathway for the electrocatalytic upgrading of biomass-based organic small molecules, offering significant reductions in energy consumption while producing value-added chemicals. The conversion of HMF to DHMF is challenging due to the high reduction potential and complex intermediates of HMF ECH under neutral environment. Also, the total efficiency is hindered by sluggish anodic oxygen evolution reaction (OER) kinetics. Herein, we report a synthesis of highly alloyed Pd-Pt bimetallene (Pd₃Pt₁ BML) for HMF ECH coupled with formic acid oxidation reaction (FAOR). Through a combination of in-situ Raman spectroscopy, electron paramagnetic resonance analysis, and theoretical calculations, we elucidate that the HMF adsorption on Pd atoms, strategically separated by Pt atoms, is weakened compared to pure Pd surfaces. Additionally, Pt atoms serve as crucial providers of active hydrogen to neighboring Pd atoms, synergistically enhancing the reaction kinetics of HMF conversion with a Faradaic efficiency >93%. Meanwhile, the atomically dispersed Pt atoms endow Pd₃Pt₁ BML with high electrochemical performance for the direct pathway of FAOR at the anode. As a result, a FAOR-assisted HMF ECH system equipped with bifunctional Pd₃Pt₁ BML achieves the energy-efficient conversion of HMF to DHMF at electrolysis voltage of 0.72 V at 10 mA cm^–2. This work provides insights into the rational design of bifunctional catalysts featuring two distinct types of active sites for advanced energy electrocatalysis and ECH.