One way of addressing the effects of CO₂ emissions on the atmosphere is to use it as a chemical feedstock in the production of useful chemicals, fuels and polymers (M. Aresta and A. Dibenedetto, Dalton Trans., 2007, 2975; C.-H. Huang and C.-S. Tan, Aerosol Air Qual. Res., 2014, 14, 480). Summarize the various approaches to using CO₂ as a feedstock and the chemistry involved in the production of organic compounds.