Bimetalene catalysts enable energy-efficient biomass conversion

Sustainable production of fuels and value-added chemicals from biomass is the basis of the future bioeconomics. 5-hydroxymethylfurfural (HMF) is a platform molecule derived from the biomass of lignocellulosia and has a great promise to replace petroleum-derived building blocks. Selective hydrogenation to 2,5-dihydroxymethylfuran (DHMF), an important precursor of pharmaceuticals, nucleoside analogs, and specialized polymers, is of particular interest. However, traditional thermally catalytic HMF hydrogenation often requires harsh conditions (high temperatures and pressure), leading to substantial energy consumption and process enhancement challenges.

A recent breakthrough published in the Journal of Catalysts presents an arbitrary alternative: electrochemical hydrogenation (ECH). A research team led by Professor Yu Chen of Shaanxi Normal University in China has developed the highly alloyed PD3PT1 bimetalene (PD3PT1BML) that enables energy-saving HMF to DHMF.

Synthesized via a simple galvanic displacement reaction, this new PD3PT1 BML exhibits a unique two-dimensional metalene structure. This morphology, combined with atomic dispersion PT in the PD lattice, offers distinct catalyst benefits. The catalyst exhibits a pronounced Farada efficiency of >93% and DHMF selectivity of >66% under mild conditions.

The exceptional performance of the PD3PT1 BML comes from the synergistic interaction of geometric and electronic effects. In-situ Raman spectroscopy provides compelling evidence for weakening of HMF adsorption at PD sites. Density functional theory (DFT) calculations support this observation and highlight the important role of PT in promoting hydrogen wave numbers and promoting hydrogenation processes. Atomic dispersion PT not only relieves catalytic poisoning by reducing the binding strength of HMF on PD, but also serves as a source of abundant active hydrogen species, thereby facilitating overall conversion.

A key innovation in this work is the strategic coupling of formic acid oxidation reaction (FAOR) at the anode and HMF ECH (at the cathode). This pair of electrolysis approaches avoid slower oxygen evolution reactions (OERs) and usually limit the efficiency of electrochemical systems. The assembled PD3PT1 BML || PD3PT1 BML electrolytic system reaches a current density of 10 mA CM-2 with a significantly lower cell voltage of just 0.72 V relative to HMF ECH.

This shows a significant voltage reduction of nearly 1 V, compared to a similar HMF ECH system in conjunction with the OER, and translates to a significant reduction in energy consumption. The synergistic ensemble and electronic effects of the PD-PT structure are central to achieving both high catalytic activity and excellent selectivity for DHMF production.