Table 3.

Comparison of different CO₂ reduction technologies.

Type	Energy	Temperature	Advantage	Challenge
Photochemical CO2 reduction	Photon	Ambient temperature	Environment-friendly; Energy conservation; Simple operability.	Low photon efficiency; Low product selectivity and reaction rate; Expensive catalysts; Low stability of the catalyst.
Electrochemical CO2 reduction	Electricity	Ambient temperature	Environment-friendly; Mild operating conditions; Good product adjustability; Rich product types.	High overpotential; Low solubility of CO2 in aqueous solutions; Liquid product mixed with electrolyte; Low Faradaic efficiencies, current densities, and high energy consumption; Low stability of the catalyst.
Thermochemical CO2 reduction	Heat	500–1000 °C	High-value product; Efficient selectivity; Large scale.	High energy consumption, high-temperature, and high-pressure conditions.