Researchers from the Institute of Solid State Physics, Hefei Institutes of Physical Science of Chinese Academy of Sciences reported a carbon supported Pt-modified MoO₃ nanoparticle catalyst for electrochemically selective C=O hydrogenation of cinnamaldehyde to produce cinnamyl alcohol.

Their findings were published in Chemical Communications.

Cinnamaldehyde (CAL), a representative platform chemical for α, β-unsaturated aromatic aldehydes, has been widely used in hydrogenation reactions to yield high value-added products. Among the hydrogenated products, cinnamyl alcohol (COL) is usually applied as a flavor additive and pharmaceutical raw material. As a newly developed approach, the electrocatalytic hydrogenation (ECH) method can be operated at ambient environment and no additional hydrogen source is required. However, the development of efficient electrocatalysts with high selectivity to COL is urgently needed to surmount the energy gap in CAL. In this work, Pt-modified MoO₃ ultrafine particles loaded on active carbon (Pt-MoO₃/C) were successfully synthesized by a facile wet-chemistry synthetic route.

Results showed that platinum clusters modified on the MoO₃ nanoparticle surface. Electrochemical characterization results demonstrated the apparent reduction peak after the introduction of CAL, and the strong adsorption of CAL on the electrode surface lead to a concentration increase in the negative shift of reduction peak.

As electrocatalyst, Pt-MoO₃/C exhibited superior electrocatalytic hydrogenation activity towards CAL to COL with high conversion of 99% and selectivity of 78% at -0.4 V (vs. RHE), and the Faradaic efficiency can reach 50% when doubling the Faraday equivalents of electric quantity applied.

The DFT calculation results indicated that the high selectivity towards COL originated from the synergistic effect of the Pt and Mo species, which could selectively adsorb the C=O bond of the CAL molecule via vertical adsorption configuration, thus improving the CAL hydrogenation selectively to generate COL.

This work was financially supported by the National Natural Science Foundation of China (Grant No. 51872292 and 52172106)