Perspectives and Challenges of CO2 Hydrothermal Reduction

The Earth’s environment is threatened by an increase in greenhouse gas CO₂ in the atmosphere that can be attributed to the rapid consumption of fossil fuels. Conversion of the greenhouse gas CO2 into high value-added chemicals and fuels is a potential method to solve both the energy and environmental problems. Many approaches for CO₂ conversion have been explored, for example, CO₂ catalytic hydrogenation, CO2 photocatalytic and electrochemical conversion, and so on. However, these processes have disadvantages such as expensive metal catalysts, low efficiency, and slow conversion rate. Thus, developing a new approach for highly efficient and rapid CO₂ conversion is urgently needed. Hydrothermal reactions can be expected to have a highly efficient, rapid, simple, and environmental CO₂ conversion, because (i) water is an environmentally friendly and recyclable reaction medium and the hydrogen derived from water can be directly used in CO₂ reduction; (ii) hydrothermal CO₂ reduction simulates the natural phenomena of abiotic synthesis of organics from CO₂; (iii) no high-purity CO₂ is needed. However, CO₂ hydrothermal conversion still faces some challenges such as (1) development of a mild reaction system, (2) development of the reactor with the characteristic of resisted corrosion, and (3) development of highly efficient and stable catalysts. Solving these challenges will help to realize the practical applications of CO2 hydrothermal reduction. This chapter presents the perspectives and challenges to CO₂ hydrothermal reductions.