Ru Species Anchored on Defective Cobalt Iron Oxide for Biomass Electro-Oxidation Coupled with Hydrogen Evolution

Abstract

Producing hydrogen at the cathode coupled with generating high-value chemicals with low energy consumption at anode in the electrolytic cell is expected to alleviate the energy crisis and meet people's demand for chemicals. However, the development of such bi-functional electrocatalysts poses great challenges. Herein, we have used low crystalline cobalt iron oxide as substrate to anchor Ru species. The Ru was mainly in the form of single Ru atoms and Ru nanoclusters. After the introduction of Ru, the electronic structure of oxide substrate has been effectively regulated, which was tend to accept electron from Ru species. With the redistributed charge density, the electrochemical ability of catalyst has been greatly improved, which only need 37 mV to reach 10 mA cm-2 for HER. Moreover, the electrocatalyst also exhibited outstanding electrocatalytic performance for 2,5-hydroxymethylfurfural oxidation with fast reaction kinetics, high yield rate and Faraday efficiency. When the electrolytic cell was constructed with this electrocatalyst as both cathode and anode, it only need 1.16 V to reach 10 mA cm-2, which was 408 mV smaller than traditional water splitting system. Theoretical calculation demonstrated that the free energy barrier has been decreased and the adsorption towards intermediates has been strengthened after the loading of Ru leading to improved electrocatalytic ability. This work provides a new idea for the development of an advanced bifunctional electrocatalyst.

Keywords: Defects, Metal-substrate interactions, Interfacial electron transfer, Biomass electro-oxidation, hydrogen evolution reaction