A comprehensive comparison of five different carbon-based cathode materials in CO2 electromethanogenesis: Long-term performance, cell-electrode contact behaviors and extracellular electron transfer pathways

• DOI: 10.1016/j.biortech.2018.06.101
• Publication Date: 2018-06-28T19:34:57Z
• Authors: Guangyin Zhen; Shaojuan Zheng; Xueqin Lu; Xuefeng Zhu; Juan Mei; Takuro Kobayashi; Kaiqin Xu; Yu-You Li; Youcai Zhao
• Keywords: Carbon fibers

Each carbon-based material, due to the discrepancy in critical properties, has distinct capability to enrich electroactive microbes able to electrosynthesize methane from CO2. To optimize electromethanogenesis process, this study physically prepared and examined several carbon-based cathode materials: carbon stick (CS), CS twined by Ti wire (CS-Ti) or covered with carbon fiber (CS-CF), graphite felt (CS-GF) and carbon cloth (CS-CC). CS-GF electrode had constantly stable methane production (75.8 mL/L/d at -0.9 V vs. Ag/AgCl) while CS-CC showed a suppressed performance over time caused by the desposition of inorganic shell. Electrode material properties affected biofilms growth, cell-electrode contact behaviors and electron exchange. Methane formation with CS-CC biocathode was H2-concnetration dependent; CS-GF cathode possessed high antifouling properties and extensive space, enriching the microorganisms capable of catalyzing electromethanogenesis through more efficient non-H2 route. This study re-interpreted the application potentials of carbon-based materials in CO2 electroreduction and electrofuel recovery, providing valuable guidance for materials' selection.