Abstract
The electrochemical transformation of biomass-derived compounds (e.g., aldehyde electroreduction to alcohols) is gaining increasing interest due to the sustainability of this process that can be exploited to produce value-added products from biowastes and renewable electricity. In this framework, the electrochemical conversion of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF) is studied. Nanostructured Ag deposited on Cu is an active and selective electrocatalyst for the formation of BHMF in basic media. However, this catalyst deserves further research to elucidate the role of the morphology and size of the coated particles in its performance as well as the actual catalyst surface composition and its stability. Herein, Ag is coated on Cu open-cell foams by electrodeposition and galvanic displacement to generate different catalyst morphologies, deepening on the particle growth mechanism, and the samples are compared with bare Ag and Cu foams. The chemical–physical and electrochemical properties of the as-prepared and spent catalysts are correlated to the electroactivity in the HMF conversion and its selectivity toward the formation of BHMF during electroreduction. AgCu bimetallic nanoparticles or dendrites are formed on electrodeposited and displaced catalysts, respectively, whose surface is Cu-enriched along with electrochemical tests. Both types of bimetallic AgCu particles evidence a superior electroactive surface area as well as an enhanced charge and mass transfer in comparison with the bare Ag and Cu foams. These features together with a synergistic role between Ag and Cu superficial active sites could be related to the twofold enhanced selectivity of the Ag/Cu catalysts for the selective conversion of HMF to BHMF, that is, >80% selectivity and ∼ 100% conversion, and BHMF productivity values (0.206 and 0.280 mmol cm–2 h–1) ca. 1.5–3 times higher than those previously reported.
Highlights
The electrocatalytic hydrogenation or reduction of biomassderived compounds is a fully sustainable alternative to thermocatalytic hydrogenation processes and a path for the storage of renewable electric energy into chemicals and liquid organic fuels.[1−4] The reduction of molecules containing aldehydes and aromatic or furan groups has been investigated
The aim of this work is to fill the gaps in the field of nanostructured Ag/Cu electrocatalysts for the reduction of aldehydes in biomass-derived compounds to the corresponding alcohols, e.g., HMF to BHMF, which could be extended to the reduction of other biomass-derived molecules
In the electrodeposited sample (Figure 1), Ag/Cu ED, arrays of Ag particles coat the surface of the Cu foam (Figure 1a), while few dendrites develop in the edges of some struts (Figure 1c,d)
Summary
The electrocatalytic hydrogenation or reduction of biomassderived compounds is a fully sustainable alternative to thermocatalytic hydrogenation processes and a path for the storage of renewable electric energy into chemicals and liquid organic fuels.[1−4] The reduction of molecules containing aldehydes and aromatic or furan groups has been investigated. The electrochemical reduction of aldehydes has been reported to occur through either a coupled proton−electron transfer process[5] or electrocatalytic hydrogenation with Hads in situ formed by the Volmer reaction (since water is usually the solvent).[8] two main competing reactions have been identified: (i) hydrodimerization leading to the formation of a diol, fostered at high substrate concentration, and (ii) hydrogen evolution reaction (HER), promoted at high overpotential.[12]. The selectivity of the reduction is Received: February 11, 2021 Accepted: May 3, 2021 Published: May 11, 2021
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