Photoelectrochemical Conversion of Carbon Dioxide (CO₂) into Fuels and Value-Added Products

The conversion of carbon dioxide (CO₂) into fuels and value-added products is one of the most significant inventions to address the global warming and energy needs. Photoelectrochemical (PEC) CO₂ conversion can be considered as an artificial photosynthesis technique that produces formate, formaldehyde, formic acid, methane, methanol, ethanol, etc. Recent advances in electrode materials, mechanisms, kinetics, thermodynamics, and reactor designs of PEC CO₂ conversion have been comprehensively reviewed in this article. The adsorption and activation of CO₂/intermediates at the electrode surface are the key steps for improving the kinetics of CO₂ conversion. PEC efficiency could be upgraded through the utilization of 2D/3D materials, plasmonic metals, carbon-based catalysts, porous nanostructures, metal–organic frameworks, molecular catalysts, and biological molecules. The defect engineered (by cation/anion vacancy, crystal distortion, pits, and creation of oxygen vacancies) 2D/3D materials, Z-scheme heterojunctions, bioelectrodes, and tandem photovoltaic–PEC reactors are suitable options to enhance the efficiency at low external bias.