Electron Localization-Triggered Proton Pumping Toward Cu Single Atoms for Electrochemical CO2 Methanation of Unprecedented Selectivity.

Slow multi-proton coupled electron transfer kinetics and unexpected desorption of intermediates severely hinder the selectivity of CO2 methanation. In this work, a one-stone-two-bird strategy of pumping protons and improving adsorption configuration/capability enabled by electron localization is developed to be highly efficient for CH4 electrosynthesis over Cu single atoms anchored on bismuth vacancies of BiVO4 (Bi1-xVO4─Cu), with superior kinetic isotope effect and high CH4 Faraday efficiency (92%), far outperforming state-of-the-art electrocatalysts for CO2 methanation. Control experiments and theoretical calculations reveal that the bismuth vacancies (VBi) not only act as active sites for H2O dissociation but also induce electron transfer toward Cu single-atom sites. The VBi-induced electron localization pumps *H from VBi sites to Cu single atoms, significantly promoting the generation and stabilization of the pivotal intermediate (*CHO) for highly selective CH4 electrosynthesis. The metal vacancies as new initiators show enormous potential in the proton transfer-involved hydrogenative conversion processes.

Hierarchical Porous MIL-101(Cr) Solid Acid-Catalyzed Production of Value-Added Acetals from Biomass-Derived Furfural.

Considering economic and environmental impacts, catalytic biomass conversion to valuable compounds has attracted more and more attention. Of particular interest is furfural, a versatile biorefinery platform molecule used as a feedstock for the production of fuels and fine chemicals. In this study, the Cr-based metal-organic frameworks (MOFs) MIL-101 were modified by chlorosulfonic acid, and MIL-101 was changed into a hierarchical MOF structure with smaller particles and lower particle crystallinity by CTAB, which significantly improved the acidic sites of the MOFs. The original and modified MIL-101(Cr) catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TEM, and FT-IR. The effects of different catalysts, reaction temperature, catalyst amount, and alcohol type on the reaction were studied. Under the action of the MOFs catalyst, a new mild route for the condensation of furfural with various alkyl alcohols to the biofuel molecules (acetals) was proposed. The conversion route includes the conversion of furfural up to 91% yield of acetal could be obtained within 1 h solvent-free and in room-temperature reaction conditions. The sulfonic acid-functionalized MIL-101(Cr) is easy to recover and reuse, and can still maintain good catalytic activity after ten runs.