CO2 Capture and Conversion to C1 Chemicals with Mixed-Metal Copper/Nickel Bis(amino)bipyrazolate Metal-Organic Frameworks

Patrizio Campitelli, Alessia Tombesi, Corrado Di Nicola*, Claudio Pettinari, Anna Mauri, Simona Galli*, Tongan Yan*, Dahuan Liu, Jiaxin Dawn Duan, Subhadip Goswami, Giulia Tuci, Giuliano Giambastiani, Joseph T. Hupp*, Andrea Rossin*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

Abstract

The reaction of 3,5-diamino-4,4′-bis(1H-pyrazole) (3,5-H2L) with copper(II) and nickel(II) acetates under solvothermal conditions led to the four mixed-metal metal-organic frameworks (MIXMOFs) [CuxNi1-x(3,5-L)] (CuxNi1-x, x = 0.05, 0.1, 0.2, 0.5), which were thoroughly characterized in the solid state. The textural analysis unveiled their macroporous nature, with BET specific surface areas falling in the 140-240 m2/g range. Despite the low specific surface areas, their CO2 adsorption capacity at ambient temperature and pressure (highest: Cu0.05Ni0.95 and Cu0.2Ni0.8; 5.6 wt % CO2) and isosteric heat of adsorption (highest: Cu0.2Ni0.8; Qst = 26.2 kJ/mol) are reasonably high. All of the MIXMOFs were tested as heterogeneous catalysts in carbon dioxide electrochemical reduction (CO2RR) in acetonitrile solution at variable potential. The best results were obtained at E = −1.5 V vs Ag/AgCl/KClsat: besides H2 from the hydrogen evolution (HER) side reaction, CO and CH4 were the main reduction products observed under the applied conditions. Cu0.05Ni0.95 showed the best performance with an overall [CO + CH4] conversion of ∼200 ppm and a Faradaic efficiency of ∼52%. CO2RR product selectivity seems to be correlated to the most abundant metal ion in the catalyst: while the Ni-richest phase Cu0.05Ni0.95 mainly produces CO, Cu0.5Ni0.5 mostly generates CH4. The preferential CO2 adsorption sites determined through GCMC simulations are close to the metal centers. For low copper loading, a prevalent end-on interaction of the type O═C═O···NiII is observed, but the progressive increase of the copper content in the MIXMOF equals the metal-gas distances with simultaneous MII···O═C═O···MII activation by two nearby metal ions and a bridging CO2 coordination mode. The analysis of the spent catalyst revealed partial formation of metal nanoparticles under the applied strongly reducing conditions.

Original languageEnglish (US)
Pages (from-to)9231-9242
Number of pages12
JournalACS Applied Energy Materials
Volume6
Issue number18
DOIs
StatePublished - Sep 25 2023

Keywords

  • Bipyrazole
  • CO Adsorption
  • CO Reduction
  • Carbon Dioxide
  • Copper
  • Electrocatalysis
  • GCMC Simulations
  • Metal−Organic Frameworks (MOFs)
  • Nickel

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Materials Chemistry
  • Electrical and Electronic Engineering

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