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The role of surface oxidation and Fe-Ni synergy in Fe-Ni-S catalysts for CO2 hydrogenation

DOI: 10.1039/D0FD00137F DOI Help

Authors: Claire E. Mitchell (Cardiff Catalysis Institute, Cardiff University) , David Santos-Carballal (University of Leeds) , Andrew M. Beale (University College London; Research Complex at Harwell) , Wilm Jones (University College London; Research Complex at Harwell) , David J. Morgan (Cardiff Catalysis Institute, Cardiff University) , Meenakshisundaram Sankar (Cardiff Catalysis Institute, Cardiff University) , Nora Henriette De Leeuw (Cardiff Catalysis Institute, Cardiff University; University of Leeds; Utrecht University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Faraday Discussions

State: Published (Approved)
Published: January 2021
Diamond Proposal Number(s): 19850

Open Access Open Access

Abstract: Increasing carbon dioxide (CO2) emissions, resulting in climate change, have driven the motivation to achieve the effective and sustainable conversion of CO2 into useful chemicals and fuels. Taking inspiration from biological processes, synthetic iron-nickel-sulfides have been proposed as suitable catalysts for the hydrogenation of CO2. In order to experimentally validate this hypothesis, here we report violarite (Fe,Ni)3S4 as a cheap and economically viable catalyst for the hydrogenation of CO2 into formate under mild, alkaline conditions at 125 oC and 20 bar (CO2:H2 = 1:1). Calcination of violarite at 200 oC resulted in excellent catalytic activity, far superior to Fe-only and Ni-only sulfides. We further report first principles simulations of the CO2 conversion on the partially oxidised (001) and (111) surfaces of stoichiometric violarite (FeNi2S4) and polydymite (Ni3S4) to rationalise the experimentally observed trends. We have obtained the thermodynamic and kinetic profiles for the reaction of carbon dioxide (CO2) and water (H2O) on the catalyst surfaces via substitution and dissociation mechanisms. We report that the partially oxidised (111) surface of FeNi2S4 is the best catalyst in the series and that the dissociation mechanism is the most favourable. Our study reveals that the partial oxidation of the FeNi2S4 surface, as well as the synergy of the Fe and Ni ions, are important in the catalytic activity of the material for the effective hydrogenation of CO2 to formate.

Subject Areas: Chemistry

Instruments: B18-Core EXAFS

Added On: 04/02/2021 08:39


Discipline Tags:

Physical Chemistry Catalysis Chemistry Organic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)