Study of fluorine doped (Nb,Ir)O2 solid solution electro-catalyst powders for proton exchange membrane based oxygen evolution reaction

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2016-10, Vol.212 (C), p.101-108
• Main Authors: Kadakia, Karan Sandeep, Jampani, Prashanth H., Velikokhatnyi, Oleg I., Datta, Moni Kanchan, Patel, Prasad, Chung, Sung Jae, Park, Sung Kyoo, Poston, James A., Manivannan, Ayyakkannu, Kumta, Prashant N.
• Format: Article
• Language: English
• Subjects: (Nb,Ir)O2:F; Electro-catalysts; Evolution; Materials science; Nanoparticles; Nanostructure; Noble metals; Oxygen; Oxygen evolution; PEM electrolysis; Reduction (electrolytic); Solid solutions; Stability
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2016.06.015

High surface area (∼300m2/g) nanostructured powders of nominal composition (Nb1−xIrx)O2 and (Nb1−xIrx)O2:10F have been synthesized and tested as oxygen evolution electro-catalysts for PEM based water electrolysis using a simple two-step chemical synthesis procedure. Superior electrochemical activity was demonstrated by fluorine doped compositions of (Nb1−xIrx)O2 with an optimal composition (Nb0.75Ir0.25)O2:10F (x=0.25) demonstrating on-par performance with commercial hydrated IrO2 and nanostructured in-house chemically synthesized IrO2. Using first principles calculations, the electronic structure modification resulting in ∼75at.% reduction (experimentally observed) in noble metal content without loss in catalytic performance and stability has been established. [Display omitted] •(Nb1−xIrx)O2:10F nanopowder electrocatalysts have been wet chemically synthesized.•(Nb0.75Ir0.25)O2:10F exhibits superior electrochemical activity than pure IrO2.•Stability of the (Nb,Ir)O2:10F nanomaterials is comparable to pure (Nb,Ir)O2.•High surface area F doped (Nb,Ir)O2 are promising OER anode electro-catalysts. High surface area (∼300m2/g) nanostructured powders of (Nb1−xIrx)O2 and (Nb1−xIrx)O2:10F (∼100m2/g) have been examined as promising oxygen evolution reaction (OER) electro-catalysts for proton exchange membrane (PEM) based water electrolysis. Nb2O5 and 10wt.% F doped Nb2O5 powders were prepared by a low temperature sol-gel process which were then converted to solid solution (Nb,Ir)O2 and 10wt.% F doped (Nb,Ir)O2 [(NbIr)O2:10F] electro-catalysts by soaking in IrCl4 followed by heat treatment in air. Electro-catalyst powders of optimal composition (Nb0.75Ir0.25)O2:10F with ∼75at.% reduction in noble metal content exhibited comparable OER activity to commercial hydrated IrO2 and nanostructured in-house chemically synthesized IrO2. The (Nb,Ir)O2:10F electro-catalyst demonstrated excellent long term structural/corrosion stability comparable to in-house chemically synthesized pure IrO2:10F. First-principles calculations of the total energies, electronic structures and cohesive energies of the model systems have been performed and correlated to the excellent activity, long term stability of (Nb,Ir)O2:F for OER obtained experimentally.