An electrochemical reactor with anode and cathode chambers separated by a composite perfluoro polymer cation exchange membrane was designed, fabricated and used for the reduction of dissolved carbon dioxide under ambient conditions to formate. The flow reactor enhanced the mass transfer of carbon dioxide compared to the batch reactor and maximum current efficiency of 93% for formate formation was obtained. A formate concentration of 1.5 Â 10 )2 mol dm )3 was obtained. Experiments were conducted using two different perfluoro polymer membranes -Nafion 961 and Nafion 430. Optimum values of flow rate and current density were evaluated for the energy efficient formation of formate in aqueous phosphate buffer solutions.

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