Regulating the Electronic Structure of Ni Sites in Ni(OH)₂ by Ce Doping and Cu(OH)₂ Coupling to Boost 5-Hydroxymethylfurfural Oxidation Performance

Abstract

Biomass is a sustainable and renewable resource that can be converted into valuable chemicals, reducing the demand for fossil energy. 5-Hydroxymethylfurfural (HMF), as an important biomass platform molecule, can be converted to high-value-added 2,5-furandicarboxylic acid (FDCA) via a green and renewable electrocatalytic oxidation route under mild reaction conditions, but efficient electrocatalysts are still lacking. Herein, we rationally fabricate a novel self-supported electrocatalyst of core−shellstructured copper hydroxide nanowires@cerium-doped nickel hydroxide nanosheets composite nanowires on a copper mesh (CuH_NWs@Ce:NiH_NSs/Cu) for electrocatalytically oxidizing HMF to FDCA. The integrated configuration of composite nanowires with rich interstitial spaces between them facilitates fast mass/electron transfer, improved conductivity, and complete exposure of active sites. The doping of Ce ions in nickel hydroxide nanosheets (NiH_NSs) and the coupling of copper hydroxide nanowires (CuH_NWs) regulate the electronic structure of the Ni active sites and optimize the adsorption strength of the active sites to the reactant, meanwhile promoting the generation of strong oxidation agents of Ni 3+ species, thereby resulting in improved electrocatalytic activity. Consequently, the optimal CuH_NWs@Ce:NiH_NSs/Cu electrocatalyst is able to achieve a HMF conversion of 98.5% with a FDCA yield of 97.9% and a Faradaic efficiency of 98.0% at a low constant potential of 1.45 V versus reversible hydrogen electrode. Meanwhile, no activity attenuation can be found after 15 successive cycling tests. Such electrocatalytic performance suppresses most of the reported Cu-based and Ni-based electrocatalysts. This work highlights the importance of structure and doping engineering strategies for the rational fabrication of high-performance electrocatalysts for biomass upgrading.

Branched Porous Ni3N as a Catalytic Electrode for Selective Semidehydrogenation of Tetrahydroisoquinoline

“…Till date, several oxidation dehydrogenation reactions of organic substrates were coupled with hydrogen liberation including the oxidation of furfural, alcohols, and urea, as well as the upgrading of biomass. − As a top-rated biomass-derived building block chemical, 5-hydroxymethyl-2-furfural (HMF) was often selected as a substrate in the anode. HMF can be oxidized into a wide range of value-added chemicals including 2,5-diformylfuran, 5-hydroxymethyl-2-furan-carboxylic acid, 5-formyl-2-furancarboxylic acid, and 2,5-furandicarboxylic acid, all of which are basic ingredients for industries to prepare commercial and daily usable materials like polymers, plastics, fibers, etc .…”