With plasmonic nanoparticles and somewhat concentrated sunlight, you can convert CO₂ to CO much more efficiently without having to use high temperatures, reports ChemCatChem. 

The call to reduce the amount of CO₂ in the air is heard worldwide. To do that, you could convert CO₂ into fuels or other useful molecules, closing the carbon cycle. The trick is to do that efficiently, because CO₂ is a fairly inert molecule and needs a lot of energy before it reacts with other molecules. Pau Martínez Molina, Francesc Sastre and colleagues from TNO in the Netherlands, Zuyd University of Applied Sciences and the Flemish Hasselt University, among others, found a short cut.