2D Materials for electrochemical carbon dioxide reduction

Abstract The traditional energy consumption mode has caused many environmental problems and the rise of the energy crisis as well. On the one hand, the reserves of unrenewable fossil energies, such as coal, oil, and natural gas, are quite limited. On the other hand, the excessive consumption of fossil energies has emitted too many environmental unfriendly products, such as the greenhouse gas CO2. In the past decade, the average CO2 emissions in the world was as high as about 32.53 billion tons per year. In 2019, the CO2 concentration in the atmosphere reached 412 ppm. The large concentration of CO2 in the atmosphere has caused many serious environmental problems, such as global warming, ocean acidification, sea-level rise, glacier melting, and climate change. To solve these problems, one way is to replace the fossil energies with renewable clean energies like wind and solar electricity, which can decrease the CO2 emissions. However, wind and solar electricity suffer from an intermittent supply, unstable frequency, and hard delivery. Another way is to directly convert CO2 to other high-value chemicals and fuels with proper physicochemical methods, like thermochemical conversion, electrochemical reduction, and photocatalytic reduction. Very recently, with the combination of the aforementioned two ways, electrochemical CO2 reduction reaction (eCO2RR) powered by clean wind and solar electricity has become the most promising solution to address the CO2-caused environmental problems. Firstly, eCO2RR can be well coupled to the local clean energy power plants to fully utilize the clean electricity by converting CO2 to value-added chemicals and fuels. Secondly, eCO2RR is an efficient technique to achieve a carbon neutral cycle. Thirdly, the eCO2RR system runs under mild conditions with relative high energy efficiency.