Evidence of CORE Coupling in Heterogenous Catalysts through Galvanic Current Analysis

Cooperative Redox Enhancement (CORE) has emerged as a promising tool to enhance bimetallic catalytic activities in liquid-phase heterogeneous catalysis. Unlike conventional alloying, CORE occurs when catalyst metals are physically separated, polarizing each metal to either the oxidation or reduction side of the reaction concerned. It has been demonstrated that through this physical separation, the catalytic activity of the precious metal catalysts Au and Pd for the oxidative dehydrogenation(ODH) of 5-hydroxymethylfurfural (HMF) is increased more than when individual activities in separate monometallic catalysts are added. This has been confirmed in both electro- and thermochemical experiment setups. (Catal. Sci. Technol., 2023,13, 47-55).

Even though the mechanism of CORE has been uncovered in recent articles, there is no direct evidence of electron flow between the two metals. Galvanic coupling tests, in which two differing monometallic catalysts that show CORE when coated bimetallically are immersed in the same solution on different electrodes and left to pass current between them, show electrochemical polarization between the active sites of each catalyst. Herein, we show clear evidence of the electron flow via galvanic coupling using ODH of HMF as a model reaction.