(Digital Presentation) OER Catalysts Supported on Layered Zirconium Phosphate Nanomaterials

Abstract

Learning from nature, instead of using expensive catalysts such as platinum for splitting water, cheaper alternatives (such as cobalt, iron, or nickel) could be used for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Hydrogen solar fuel produced in artificial photosynthesis schemes for water splitting could be used in fuel cells. However, obtaining efficient catalysts based on earth-abundant materials is still difficult, particularly for the OER. Recent theory has shown that nanoscopic confinement of catalysts increases the stability and efficiency of catalysts for OER. We have designed and develop earth-abundant electrocatalysts for oxygen reduction and water splitting using nanostructured layered inorganic materials of zirconium phosphate (ZrP). We have demonstrated improved electrocatalytic activity of ZrP nanomaterials loaded with metal ions suitable for the OER of water splitting. Adsorbing Co or Ni catalysts on the ZrP nanoparticles surface proved to improved OER activity compared to intercalated catalysts. A comparison between adsorbed Co or Ni catalysts and those catalysts on exfoliated ZrP hexagonal nanoplatelets proved that those on exfoliated nanoplatelets were more active, with diminished overpotentials and reduced Tafel plot slopes as well as higher mass activities. More recently, comparison between Co and Ni catalyst on ZrP particles with different morphologies (hexagonal platelets, rods, cubes, and spheres) revealed that the more active Co catalysts are those on hexagonal ZrP platelets, whereas the best Ni catalysts are those on ZrP spheres. Finally, encouraging recent results with a cobalt porphyrin catalyst and bimetal catalysts will be presented, as well as recent XAS operando results. These results demonstrate that ZrP nanoparticles are suitable supports for electrocatalysis of the OER and water splitting.Sponsored by the NSF-PREM Center for Interfacial Electrochemistry for Energy Materials (CIE2M) grant DMR-1827622.