Environmental problems such as global warming are one of the most prominent global challenges. Researchers are investigating various methods for decreasing CO₂ emissions. The CO₂ reduction reaction via electrochemical, photochemical, and photoelectrochemical processes has been a popular research topic because the energy it requires can be sourced from renewable sources. The CO₂ reduction reaction converts stable CO₂ molecules into useful products such as CO, CH₄, C₂H₄, and C₂H₅OH. To obtain economic benefits from these products, it is important to convert them into hydrocarbons above C₂. Numerous investigations have demonstrated the uniqueness of the C-C coupling reaction of Cu-based catalysts for the conversion of CO₂ into useful hydrocarbons above C2 for electrocatalysis. Herein, the principle of semiconductors for photocatalysis is briefly introduced, followed by a description of the obstacles for C₂₊ production. This review presents an overview of the mechanism of hydrocarbon formation above C₂, along with advances in the improvement, direction, and comprehension of the CO₂ reduction reaction via electrochemical, photochemical, and photoelectrochemical processes.