CeO2-regulated NiCoOOH formed via electrocatalytic self-reconstruction of NiCoCe-MOFs for efficient electro-oxidation of 5-hydroxymethylfurfural

Abstract

A CeO₂-regulated NiCo oxyhydroxide nanosheet electrocatalyst (i.e., CeO₂/NiCoOOH) was fabricated by electrocatalytic self-reconstruction of NiCoCe-MOFs. The in situ self-reconstruction exposes additional active sites on the NiCoOOH surface, leading to enhanced intrinsic electrocatalytic activity. CeO₂/NiCoOOH has better performance in both the OER and the HMFOR than the original MOFs. CeO₂ acts as an ‘electron trap’, modulating the electron density of Ni and Co, refining the electronic configuration of NiCoOOH and expediting the electron transfer kinetics. Therefore, the self-reconstructed CeO₂/NiCoOOH shows higher current density (92.7 mA cm⁻²) than NiCoOOH (49.8 mA cm⁻²) in electrocatalytic oxidation at 1.5 V_RHE (1.0 M KOH + 50 mM HMF). After 5 cycles of testing, CeO₂/NiCoOOH still has excellent HMF conversion (95.87%), Faraday efficiency (95.22%) and FDCA yield (99.26%). Theoretical calculations revealed that the introduction of CeO₂ significantly lowers the energy barrier for the critical step at the Co site and optimizes the adsorption of HMF, thereby facilitating the electrocatalytic HMFOR process.