Towards sustainable H2 evolution by using an algal-electro-photosynthetic process: The mediator selection alternates the electron sources for Chlorella sorokiniana SU-1

• Published in: International journal of hydrogen energy Vol. 48; no. 46; pp. 17409 - 17419
• Main Authors: Li, Shiue-Lin, Liao, En-Ci, Lin, Yu-Jun, Lu, Yun-Ju, Zhang, Yu-Sheng, Tseng, Yen-Tzu, Jiang, Yu-Jie, Chiang, Tzu-Hao, Gao, Zhi-Xiang, Li, Pei-Xuan, Chang, Jo-Shu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 29.05.2023
• Subjects: 2,6-dimethoxy-1,4-benzoquinone; Algal biological-photoelectrochemical-H2-evolution process; Chlorella sorokiniana SU-1; Ferricyanide; Ferricyanide; Chlorella sorokiniana SU-1; 2,6-dimethoxy-1,4-benzoquinone; Algal biological-photoelectrochemical-H2-evolution process
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2023.01.226

Chlorella sorokiniana SU-1 is employed on the graphite-felt anode of a two-chamber cell connecting potentiostat (+0.4 V vs Ag/AgCl) to study its photoelectrochemical characteristics. Among the mediators selected, the current significantly reached 1.5 mA and 4.0 mA, respectively, when 0.3 mM 2,6-dimethoxy-1,4-benzoquinone and 5.5 mM ferricyanide were spiked. To give significant hydrogen evolution, the applied direct-circuit voltage could be reduced from 2.0 to 1.3 V (producing 1.5 mL-H2 h−1) due to the assistance of the algae-attached anode and platinum-mesh cathode. The current was boosted by spiking 0.2 g L−1 glucose under light/dark conditions. When using ferricyanide as a mediator, the current oscillated under alternating light-on/off conditions, while for 2,6-dimethoxy-1,4-benzoquinone, the increase or decrease of the current was clearly responding to the light going on and off. The microscopic observation of the SU-1 cell attachment indicates successful development by offering adequate illumination and electrode surfaces. [Display omitted] •H2 evolution by using the algal-electro-photosynthetic process is feasible.•Ferricyanide was found to be the best mediator in boosting current generation.•The ferricyanide impairs the photosynthetic system of Chlorella sorokiniana SU-1.•The principal e− source for the photochemical current is cellular saccharide storage.