This chapter focuses on recent progress in nanoparticle design and synthesis for selective conventional catalytic, photocatalytic, electrocatalytic, photoelectrocatalytic and photothermal catalytic conversions of CO2 to reusable low carbon-based products, such as carbon monoxide, methane, methanol, formic acid, ethylene and many more, as sustainable feedstocks for fuels (or precursors) and chemicals, in order to protect our natural environment.