Photocatalytic Fuel Cell (PFC) and Dye Self-Photosensitization Photocatalytic Fuel Cell (DSPFC) with BiOCl/Ti Photoanode under UV and Visible Light Irradiation

A fuel cell that functioned as a photo fuel cell (PFC) when irradiated with UV light and as a dye self-photosensitization photo fuel cell (DSPFC) when irradiated with visible light was proposed and investigated in this study. The system included a BiOCl/Ti plate photoanode and a Pt cathode, and dye solutions were employed as fuel. Electricity was generated at the same time as the dyes were degraded. 26.2% and 24.4% Coulombic efficiency were obtained when 20 mL of 10 mg·L^–1 Rhodamine B solution was treated with UV for 2 h and visible light for 3 h, respectively. Irradiation with natural and artificial sunlight was also evaluated. UV and visible light could be utilized at the same time and the photogenerated current was observed. The mechanism of electricity generation in BiOCl/Ti PFC and DSPFC was studied through degradation of the colorless salicylic acid solution. Factors that affect the electricity generation and dye degradation performance, such as solution pH and cathode material, were also investigated and optimized

Distinct Mechanisms on Accelerating Electron Transfer to Facilitate Two-Stage Anaerobic Digestion Modulated by Various Microalgae Biochar

Microalgae-derived biochar are promising candidates to accelerate electron transfer during anaerobic digestion (AD) due to inherent advantages, but the mechanisms are unclear since they are highly related to microalgae species. In this work, distinct electron transfer mechanisms modulated by biochar derived from Scenedesmus sp. (SBC) and Chlorella sp. (CBC) were investigated during two-stage AD. Overall, adding biochar enhanced direct interspecies electron transfer (DIET) by increasing the relative abundance of related microorganisms like Firmicutes and Methanosaeta. Furthermore, SBC showed a foamy honeycomb structure with abundant functional groups, a rough surface, and irregular holes, which provided habitats for microorganism colonization and acted as an electron conductor for facilitating conductive material-mediated DIET (i.e., cDIET). Meanwhile, CBC showed a closed spherical granule structure having a smooth surface and low porosity, leading to stack of microorganisms on the biochar surface and causing bioelectrically triggered DIET (i.e., bDIET) via upregulated secretion of Flavins and C-type cytochromes. Results indicate that the electron transfer rate via bDIET was one order of magnitude higher than that via cDIET, resulting in a 53.9% increase on H2 yield and a 9.1% increase on CH4 yield in the CBC group compared to SBC group. These findings can enrich knowledge gaps of electron transfer mechanisms modulated by microalgae biochar and may inspire more efficient AD processes