High-Flux Solar-Driven Thermochemical Dissociation of CO ₂ and H ₂ O Using Nonstoichiometric Ceria

Fuel from Heat

Plants grow by using energy from the Sun to convert carbon dioxide into sugar-based polymers and aromatics. These compounds in turn can be stripped of their oxygen, either through millennia of underground degradation to yield fossil fuels, or through a rather more rapid process of dissolution, fermentation, and hydrogenation to yield biofuels. Can we use sunlight to turn CO ₂ into hydrocarbon fuel without relying on the intervening steps of plant growth and breakdown? Chueh et al. (p. 1797 ) demonstrate one possible approach, in which concentrated sunlight heats cerium oxide to a sufficiently high temperature (∼1500°C) to liberate some oxygen from its lattice. The material then readily strips O atoms from either water or CO ₂ , yielding hydrogen or CO, which can then be combined to form fuels.