The Structural Phase Effect of MoS2 in Controlling the Reaction Selectivity between Electrocatalytic Hydrogenation and Dimerization of Furfural

摘要

The development of a multifunctional electrocatalyst for upgrading biomass-derived platform molecules can diversify the product outcomes of a biorefinery and strengthen its role in the current petroleum-dominated economy. This study demonstrated how the structural phase distribution of a transition metal dichalcogenides (TMDs) catalyst, MoS2, can be exploited to control the reaction pathway between electrocatalytic hydrogenation (ECH) and electrocatalytic dimerization (ECD) of furfural (FFL). A series of carbon-supported MoS2 electrodes with different structural phase distributions, 1T and 2H, were prepared and fully characterized. The electrodes displayed good stability and successfully converted over 98% of FFL to target products. Under optimized conditions, the 1T-rich MoS2 electrodes were highly selective in producing an ECH product, furfuryl alcohol, with a selectivity of 94.4% over the ECD product, hydrofuroin, whereas the 2H-rich MoS2 electrodes achieved up to 42.7% selectivity for an ECD product. Mechanistic investigation with underpotential hydrogen desorption (H-UPD) studies and density functional theory (DFT) calculation revealed that 1T and 2H-MoS2 played very different roles during the electrolysis of FFL. The HER-active 1T phase was less friendly to FFL's adsorption than the 2H phase, but its ability to generate adsorbed hydrogen (H-ads) provided the necessary component to complete the ECH process. The 2H phase was a better platform for FFL and its radical intermediate adsorption, but its H-ads-deficient surface led to more ECD product. This study expands the opportunity to design multiphasic materials to control product selectivity during the electrocatalytic reduction of aldehyde compounds.

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