New trends in the development of heterogeneous catalysts for electrochemical CO2 reduction

The electrochemical conversion of CO2 into energy-rich fuels and chemicals has gained significant interest as a potential strategy for simultaneously mitigating increasing global CO2 concentration and effectively storing intermittent renewable energy from sources such as solar and wind. This process recycles CO2, permitting a carbon-neutral, closed-loop of fuel combustion and waste CO2 reduction to help prevent a rising concentration of this greenhouse gas in the atmosphere. At the same time, intermittent electricity generation can be stored in an energy-dense, portable form in chemical bonds. However, the stability of CO2 makes its conversion kinetically challenging, generally requiring a large overpotential, and thus the efficiency of electrochemical CO2 reduction is strongly dependent on the activity and selectivity of the cathodic electrocatalyst. In this review, we discuss the current state-of-the-art of unconventional heterogeneous catalysts with a focus on activity and product selectivity, even if the CO2 reduction reaction mechanism remains uncertain. Various emerging approaches to enhance the yield of specific products and the overall rate of reaction will also be addressed. Finally, prospects for the development of next generation catalysts will be discussed. (C) 2016 Elsevier B.V. All rights reserved.