Study of carbon dioxide sequestration and electricity generation by a new hybrid bioenergy system with the novelty catalyst

Abstract

• The proposed PBR-MFC hybrid system presents the outstanding performance of CO 2 fixation and electricity generation. • MFC promotes DO consumption efficiency and biomass concentration of system. • The PBR-MFC performs the better performance in CO 2 fixation efficiency (20.7 %) and power density (404 mW·m −2 ) with the novelty catalyst. • A novelty, cost-effective ORR catalyst (Zn 3 /Co 2 /Fe 0.1 -MOFs) shows a 59.5 % increase in the maximum power density (850 mW·m-2, 1.8 $·g-1) of MFCs and a 95.8 % decrease in material cost compared to that of Pt/C (533 mW·m-2, 42.65 $·g-1), respectively. This paper proposed a hybrid bioenergy system to enhance CO 2 fixation and electricity generation through the integration of a single-chamber microbial fuel cell (MFC) and a columnar photobioreactor (PBR). In this hybrid system, microalgal photosynthesis can continuously supply O 2 to the cathode of MFC, and the elimination of dissolved oxygen is conducive to the improvement of CO 2 fixation efficiency. However, affected by microalgae solution, the power generation of this system is limited. To further improve power output, a series of Co-based ternary metallic metal–organic frameworks (tri-MOFs) with controllable metal ratios are produced. It can be adopted as an efficient oxygen reduction reaction (ORR) catalyst through a facile sulfuration-pyrolysis treatment. The ORR performances of MOFs-derived composites are fully evaluated in both alkaline and neutral environments. The proposed catalyst achieves comparable ORR activity and superior durability to the Pt/C, because the formation of a three-dimensional porous structure facilitates electron transport. Different cathode catalysts for the CO 2 fixation efficiency and power generation of PBR-MFC hybrid systems are studied. The results present below.(1) The maximum power density of MFCs in this paper (850 mW·m −2 ) indicates a rise of 59.5 % by this sample, comparing with the level of Pt/C (533 mW·m −2 ). The material costs are 1.8 $·g −1 , which is 95.8 % lower than the costs of Pt/C (42.65 $·g −1 ). (2) Due to the enhanced consumption efficiency of dissolved oxygen and microalgae growth rate, the maximum CO 2 fixation efficiency and power density of in PBR-MFC hybrid bioenergy system can achieve 20.7 % and 404 mW·m −2 , respectively. The results obtained by cathodic MOFs-derived MFC with low cost and outstanding oxygen consumption efficiency, would provide a new sight on CO 2 fixation and bioenergy generation.