Biomass, as a novel type of renewable non-fossil resources, is considered as potential alternatives for mitigating the anthropogenic climate risk and meeting the strict requirement for environmental protection and sustainable development. 5-hydroxymethylfurfural (HMF) as an important dehydration product derived from cellulosic biomass is of great potential as a platform substrate to produce value-added feedstocks. The electrooxidation of HMF was coupled with the hydrogen evolution reaction that has relatively high research significance in the field of sustainable energy, which is considered as a green strategy with great potential application prospect. This novel strategy has attracted the attention of researchers in the fields of catalysis, energy and material science and has achieved rapid development. However, this research area is still in the initial stage of proof-of-concept and faces many scientific challenges.
The research team led by Prof. QI Wei in Energy Catalysis & Materials group, Shenyang National Laboratory for Materials Science (SYNL), Institute of Metal Research (IMR) fabricated a new composite electrode material of nickel nanosheets uniformly grown on carbon paper substrates using electrodeposition technology. This carbon-based hybrid catalytic material has shown high efficiency in electro-reforming of HMF, and which is also used to explore the catalytic mechanism and structure-activity relationship on HMF electro-oxidation. The paper of this research work is published in the Angewandte Chemie International Edition.
The prepared Ni nanosheet/carbon paper composite electrode could catalyze the oxidation of HMF to 2, 5-furanediocarboxylic acid (FDCA) at a low reaction potential (1.36 VRHE) with high selectivity, and the coupled hydrogen evolution reaction also exhibited relatively high efficiency. The FDCA yield and selectivity of the reaction system are close to 100%, and the Faraday efficiency of H2 evolution is 95.3%. The catalyst showed high stability after multiple reuse cycles. The excellent catalytic performance was proved to be derived from the relatively low crystallinity, abundant edge sites and unique electronic structure of the nickel nanosheets supported on carbon paper. The Ni0 on the edge within electron-deficient state was easily oxidized in situ to Niδ+ species with higher valence (NiO or NiOOH small clusters) during the reaction process, which significantly improved the catalytic activity of the Ni nanosheet/carbon composite electrode. The density functional theory calculations had identified the catalytic reaction path and revealed that the enhancement of the catalytic activity is mainly due to the favorable adsorption configuration of HMF on Niδ+ species, high adsorption energy and low energy barrier of the elementary reaction step.
The proposed novel nickel nanosheet/carbon composite electrode showed ideal catalytic activity, energy efficiency and stability in the electrooxidation reaction of HMF, which provided a new idea for the efficient sustainable utilization of biomass resources. Furthermore, the present work also emphasized the importance of mechanistic understandings and structure engineering under atomic level for the rational design of highly efficient electrocatalysts.
Morphology and activity of nickel/carbon composite electrode (Image by IMR)
Exploration of the origin of high activity and the structure-function relationship of nickel nanosheet/carbon composite electrode (Image by IMR)
