CeO2 as an “electron pump” to boost the performance of Co4N in electrocatalytic hydrogen evolution, oxygen evolution and biomass oxidation valorization

Developing multifunctional electrocatalysts with excellent hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and 5-hydroxymethylfurfural oxidation reaction (HMFOR) activities will contribute to "carbon neutrality". Here, CeO2 is introduced into the Co4N system as an "electron pump" to attract electrons to transfer from Co4N to CeO2. The interface electronic structure optimization enables Co4N@CeO2 to exhibit excellent HER, OER, and HMFOR performance. Specifically, to deliver 10 mA cm−2 current density, (1) it only requires low overpotentials of 49 and 263 mV for HER and OER in 1.0 M KOH, respectively; (2) it merely needs an ultra-low potential of 1.22 VRHE for HMFOR in 1.0 M KOH + 300 mM HMF, which is 273 mV lower than the required potential in 1.0 M KOH. Theoretical calculation results show that the introduction of CeO2 effectively reduces the barriers for potential-determining steps of HER and OER, and optimizes OH- adsorption to promote the HMFOR process. [Display omitted] •A multifunctional Co4N@CeO2 is designed for electrochemical HER, OER and HMFOR.•CeO2 extracts electrons from Co4N and optimizes interfacial electronic structure.•Favorable H2O adsorption/dissociation and △G*H of Co4N@CeO2 accelerate HER.•Introduction of CeO2 lowers the potential-determining step barrier of OER.•Strong adsorption of Co4N@CeO2 to OH- is beneficial to the HMFOR process.