Flinders NanoCentre, the Ian Wark Institute and the University of Adelaide have joined forces in a South Australian collaboration to explore catalyst-co-catalyst systems in the hopes of finding efficient routes to reduce CO₂ and oxidise water simultaneously in the gas phase to form methanol, methane or ethanol.

With the combination of Electron Spectroscopy (XPS/UPS/MIES), UV-Vis Absorption Spectroscopy, Transient Absorption Spectroscopy, Photoluminescence Spectroscopy and Electrochemistry we will be able to investigate a catalyst and co-catalyst system and relate electronic structure to the reactivity of catalyst systems in the reduction of CO₂ and oxidation of H₂O under solar illumination.

Traditionally the reduction of water is thought to take place on the surface of the noble metal co-catalyst, where sunlight excites an electron-hole pair in the photocatalyst and the electron from the support catalyst transfers to the co-catalyst to be utilised in the reduction of protons to form molecular hydrogen.

Recently a new model of water splitting was proposed by Bong Joo et al¹ from the University of California.

This model, supported by fluorescence data, points to the photocatalyst performing both reduction of protons and oxidation of water. Whilst the co-catalyst serves to form dihydrogen from atomic hydrogen, countering the recombination of hydrogen and oxygen to form water.

The formation of hydrocarbons from water and CO₂ could perhaps begin by the formation of hydrogen molecules on the co-catalyst surface followed by a Sabatier reaction on the same co-catalyst. Rather than the multi-proton, multi-electron CO₂ reduction model currently proposed in literature.

If this is true, the emergence of a new exploratory method for catalyst systems in a decades old topic could present new avenues to efficient conversion of CO₂ and H₂O into fuels.

Posted by Dr Rantej Kler, Postdoc with Assoc. Prof. Gunther Andersson in collaboration with Prof. Thomas Nann (UniSA) and Prof. Greg Metha (Adelaide).

 

1. Joo, Ji Bong, Robert Dillon, Ilkeun Lee, Yadong Yin, Christopher J. Bardeen, and Francisco Zaera. “Promotion of atomic hydrogen recombination as an alternative to electron trapping for the role of metals in the photocatalytic production of H₂.” Proceedings of the National Academy of Sciences 111, no. 22 (2014): 7942-7947. http://www.pnas.org/content/111/22/7942.short