Organic reactions for the electrochemical and photochemical production of chemical fuels from CO_2 – The reduction chemistry of carboxylic acids and derivatives as bent CO_2 surrogates

The present review covers organic transformations involved in the reduction of CO_2 to chemical fuels. In particular, we focus on reactions of CO_2 with organic molecules to yield carboxylic acid derivatives as a first step in CO_2 reduction reaction sequences. These biomimetic initial steps create opportunities for tandem electrochemical/chemical reductions. We draw parallels between long-standing knowledge of CO_2 reactivity from organic chemistry, organocatalysis, surface science and electrocatalysis. We point out some possible non-faradaic chemical reactions that may contribute to product distributions in the production of solar fuels from CO_2. These reactions may be accelerated by thermal effects such as resistive heating and illumination.