Relay electrocatalysis with bimetallic sites for highly efficient oxidation in multiple cascade reaction

The majority of electrocatalytic conversions of biomass-based molecules involve multiple steps utilizing the cascade reactions. As a result, maintaining the consecutive rate of each independent step is vital to improving the efficiency of the reaction. Whereas the single active species cannot entirely satisfy the demand of synchronous rates. Even with the use of bimetallic catalysts, the focus is still on facilitating the rate of the controlling step in the whole reaction. In this study, the NiCo-metal-organic framework (MOF) with diatomic sites was designed for the relay electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The prepared Ni2Co1-MOF catalyst exhibited 97.3 % FDCA yield, and 90 % faradaic efficiency, and an excellent stability. Incorporating favorable catalytic activities of Ni and Co facilitates the alcohol-to-aldehyde and aldehyde-to-carboxylic acid conversions, respectively, verifying the relay effect with lower energy demand (1.35 V vs. RHE). Moreover, the ultrashort distance between two sites results in the faster diffusion of intermediates, further accelerating the reaction. The industrial simulation experiment using a pilot reaction equipment demonstrates the satisfied demands for industrial applications. This relay electrocatalysis path provides new insight into the rational design of catalysts for facilitating the electrorefining process with muti-step reactions.