High-efficiency electrochemical hydrogenation of biomass-derived benzaldehyde compounds via a durable and versatile dendritic-like Pd/Cu-CF electrocatalyst

The electrocatalytic upgrading of benzaldehyde compounds from biomass using water as the hydrogen source is a green and promising approach to produce value-added benzyl alcohol products. The fabrication of advanced electrocatalysts plays an essential role for the development of biomass electrochemical conversion process. In this work, we successfully synthesized the dendritic-like Pd/Cu-CF-II electrocatalyst with high capacitance (22.9 mF cm−2) and low charge transfer resistance (Rct) of 3.7 Ω by a two-step electrodeposition process. Taking vanillin (VL) as the substrate, the self-prepared electrode facilitated the efficient electroreduction of VL into vanillyl alcohol (VA) with up to 97.58% conversion and faradaic efficiency (FE) of 96.22%. After five successive electrolysis cycles, the Pd/Cu-CF-II electrocatalyst still showed superior effectiveness and good stability with slightly dropped conversion of VL and FE. This electroreduction system also displayed favorable versatility for the conversion of other benzaldehyde compounds, such as benzaldehyde, p-amino benzaldehyde, p-nitro benzaldehyde, o-carboxyl benzaldehyde and syringaldehyde, with more than 83% conversion, 80% FE and 95% selectivity as well. Mechanisms for the high-selectivity electrochemical hydrogenation of benzaldehyde compounds into benzyl alcohols were proposed and discussed. This study provides a novel and green route to efficiently upgrade biomass-derived compounds into valuable fine chemicals.