Construction Of Photocatalytic Benthic Microbial Fuel Cell And Its Performance On Power Production

In the process of industrialization,with the rapid increase in emissions,environmental pollution is deteriorating.Developing new energy sources that have little impact on the environment is critical to sustaining economi c growth and maintaining human green life.Microbial fuel cell?MFC?is a new technology that combines the two efficiencies of sewage treatment and bio-production,which can chieve this goal possible for the energy sector,showing the broad prospects of new energy development and utilization.The benthic microbial fuel cell?BMFC?as a special kind of MFC,the life can be equal to or even exceed the sensor,which is expected to be a new type of power system that can be stable for long periods of time and does not require regular maintenance.The main factor for limiting its practical use is the low power density.In this study,we propose to construct the photocatalytic benthic microbial fuel cell?photo-BMFC?for the first time by using the synergistic effect of photocatalytic reduction and microbial fuel cell.Using semiconductor photocathode can increase cathode electron conversion efficiency,thus improving the overall output voltage and power density of the BMFC.The main contents and results are as follows:?1?According to the characteristics of the semiconductor Cu₂ O having a good response to visible light,Cu₂ O photocatalyst prepared on the copper substrate.FE-SEM and XRD results show that Cu₂ O photocatalyst can be successfully obtained by thermal oxidation method on the copper substrate,referred to as Cu₂O/Cu electrode.In order to suppress the self-reduction of Cu₂ O in the Cu₂O/electrolyte interface,a thin protective carbon layer was formed on the surface of Cu₂ O,referred to as C/Cu₂O/Cu electrode.The photoelectric properties of the electrode were measured by LSV and I-T electrochemical methods.The results show that the synthesized C/Cu₂O/Cu photoelectricity is higher than that of the blank Cu₂O/Cu,and the chemical stability is improved.?2?Cu₂O as the cathode photocatalyst of BMFC: The photocatalytic BMFC with C/Cu₂O/Cu as cathode,which was designed to test the change of photocatalytic activity of BMFC under ultraviolet and dark conditions.By measuring the photogenerated current and the photogenerated voltage curve,the difference of the photocurrent density between the ultraviolet light and the dark is 0.03 m A/cm2 and the photogenerated voltage difference is 0.05 V.The polarization curve shows that the internal resistance photocatalytic BMFC?C/Cu₂O/Cu?is 190 ?,the maximum power density is 0.01 m W/cm2,the internal resistance is 436 ? without light,and the power density is 0.0074 m W/cm2.The results show that the output power of the photocatalytic BMFC is larger and the internal resistance decrea ses under the ultraviolet light,and the effect of Cu₂ O as the photocatalyst on the BMFC performance is significant.?3?Based on the results of the study,it was determined that the photocatalyst was Cu₂ O,and the unstable copper substrate was replaced with carbon felt substrate.The Cu₂ O electrodeposition method was first combined with the carbon felt base to make the carbon felt substrate Cu₂ O photocathode.FE-SEM,EDX and XRD results show that the carbon felt substrate Cu₂ O photocathode is successfully prepared by electrodeposition.The prepared Cu₂O/carbon felt photocathode surface is also carbon-coated to prepare carbon-coated carbon felt base Cu₂ O electrode,referred to as C/Cu₂O/carbon felt electrode.The results of LSV and I-T show that the Cu₂O/carbon felt electrode and after carbon layer coated C/Cu₂O/carbon felt electrode is better,which can provide suitable photocathode for the construction of photocatalytic BMFC.?4?Construction of photocatalytic BMFC and its productivity study: The photocatalytic BMFC with Cu₂O/carbon felt,C/Cu₂O/carbon felt as the photocathode and the common BMFC with carbon felt as the cathode,referred to as common BMFC.The effect of photocathode on the performance of BMFC was studied.The results show that the photocatal ytic BMFC has a small internal resistance compare with common BMFC?carbon felt?,which has a large output power and a significant performance.The maximum value of photo-BMFC?C/Cu₂O/carbon felt?is 0.0249 m W/cm2 in white light,96% higher than 0.0127 m W/cm2 of photo-BMFC?Cu₂O/carbon felt?,increases by 15 times compare with common BMFC?carbon felt?0.00152 m W/cm2.The photogenerated current and the photogenerated voltage indicates that photocurrent density of photo-BMFC?Cu₂O/carbon felt?is about 0.10 m A/cm2,in the dark and white light alternately,the photocurrent density difference is 0.02 m A/cm2,the voltage difference is about 0.025 V.The current density of common BMFC?carbon felt?is 0.04 m A/cm2,the voltage in the dark and light is basically constant,indicating that Cu₂ O photocatalyst can improve its production capacity by using light energy coupling BMFC.Combining the polarization curve and EIS diagram,the photocatalytic BMFC?Cu₂O/carbon felt?and photocatalytic BMFC?C/Cu₂O/carbon felt?compared to common BMFC?carbon felt?produced a smaller internal resistance.The BMFC performance is optimized.