Heterogenization of a [NiFe] Hydrogenase Mimic through Simple and Efficient Encapsulation into a Mesoporous MOF

Inorg Chem. 2017 Dec 18;56(24):14801-14808. doi: 10.1021/acs.inorgchem.7b01824. Epub 2017 Dec 1.

Abstract

In the quest for new, efficient, and noble-metal-free H2-evolution catalysts, hydrogenase enzymes are a source of inspiration. Here, we describe the development of a new hybrid material based on a structural and functional [NiFe]-hydrogenase model complex (NiFe) incorporated into the Zr-based MOF PCN-777. The bulk NiFe@PCN-777 material was synthesized by simple encapsulation. Characterization by solid-state NMR and IR spectroscopy, SEM-EDX, ICP-OES, and gas adsorption confirmed the inclusion of the guest. FTO-supported thin films of the NiFe@PCN-777 composite were obtained by electrophoretic deposition of the bulk material and characterized by SEM-EDX, ICP-OES, and cyclic voltammetry. The average surface concentration of electroactive NiFe catalyst in the film was found to be ∼9.6 × 10-10 mol cm-2, implying that a surprisingly high fraction (37%) of NiFe units incorporated in the MOF are electroactive. By cyclic voltammetry, we showed that NiFe maintains its electrocatalytic capabilities for H+ reduction inside the MOF cavities, even if under controlled-potential electrolysis conditions the activity of NiFe cannot be discerned from that of free PCN-777 and FTO.

MeSH terms

  • Biomimetic Materials / chemistry*
  • Catalysis
  • Electrochemical Techniques
  • Hydrogenase / chemistry*
  • Iron / chemistry*
  • Metal-Organic Frameworks / chemistry*
  • Models, Molecular
  • Nickel / chemistry*
  • Oxidation-Reduction
  • Protons
  • Zirconium / chemistry*

Substances

  • Metal-Organic Frameworks
  • Protons
  • Nickel
  • Zirconium
  • Iron
  • nickel-iron hydrogenase
  • Hydrogenase