459558 Solar Thermochemical CO2 Splitting Via Redox Cycling with Low-Cost Metal Oxide Nanostructures
Xiang Gao1*, Peter Kreider2, Alicia Bayon3, Thomas Gengenbach4, Jim Hinkley3, Wojciech Lipiński2, Antonio Tricoli1
1Nanotechnology Research Laboratory, Research School of Engineering, The Australian National University, Canberra, ACT 2601, Australia
2Solar Thermal Group, Research School of Engineering, The Australian National University, Canberra, ACT 2601, Australia
3CSIRO Energy, P.O. Box 330, Newcastle, NSW 2300, Australia
4CSIRO Manufacturing, Bayview Avenue, Melbourne, VIC 3168, Australia
Solar thermochemical two-step metal oxide redox cycles are viewed as a viable pathway to produce syngas via water splitting (WS) and carbon dioxide splitting (CDS). Syngas is an important intermediate in the creation of commercial products such as hydrocarbon fuels and ammonia. Using a carbothermal reduction step such as methane partial oxidation (MPO) can alleviate some of the process requirements by decreasing the reduction temperature and increasing the fraction of the oxygen carrier undergoing reaction. Recent studies on metal oxides for MPO–CDS/WS solar thermochemical redox cycles have demonstrated potential improvements to the steady-state solar-to-fuel efficiency. A major challenge is engineering redox materials that can maintain reactivity and stability over many cycles, achieve high non-stoichiometry in the reduction step, and promise large-scale production at low cost.
Here, we present a novel low-cost earth abundant metal oxide nanostructure with as much as ten times higher redox capacity and up to 60% faster reaction kinetics compared to state-of-the-art ceria nano-powders. This composite shows promising long-term stability and maintains a significant fraction of its initially high syngas production rates over multiple MPO–CDS cycles. Structural properties such as crystal phase composition and size, specific surface area, pore volume and particle size distribution were characterised before and after thermochemical cycling. These initial results demonstrate a promising pathway towards development of stable, reactive and low-cost redox material for two-step solar thermochemical fuel production.