Abiotic-biotic hybrid for CO2 biomethanation: From electrochemical to photochemical process.

Converting CO2 into sustainable fuels (e.g., CH4) has great significance to solve carbon emission and energy crisis. Generally, CO2 methanation needs abundant of energy input to overcome the eight-electron-transfer barrier. Abiotic-biotic hybrid system represents one of the cutting-edge technologies that use renewable electric/solar energy to realize eight-electron-transfer CO2 biomethanation. However, the incompatible abiotic-biotic hybrid can result in low efficiency of electron transfer and CO2 biomethanation. Herein, we present the comprehensive review to highlight how to design abiotic-biotic hybrid for electric/solar-driven CO2 biomethanation. We primarily introduce the CO2 biomethanation mechanism, and further summarize state-of-the-art electrochemical and photochemical CO2 biomethanation in hybrid systems. We also propose excellent synthetic biology strategies, which are useful to design tunable methanogenic microorganisms or enzymes when cooperating with electrode/semiconductor in hybrid systems. This review provides theoretical guidance of abiotic-biotic hybrid and also shows the bright future of sustainable fuel production in the form of CO2 biomethanation.