Investigation On Construction And Performance Of The Photocatalytic Fuel Cell With Capacitive Anode

Photocatalytic fuel cell（PFC）is a promising wastewater recycling technology,which can effectively synchronize solar energy utilization,electricity generation and wastewater treatment through photoelectric chemical reaction.However,due to the low absorption rate of sunlight to the photoanode and the high electron-hole recombination rate,the photoelectric conversion rate of PFC is low,which leads to the low output current density of the battery.Aiming at the above problems,this paper combines the capacitor material with the photocatalytic anode of PFC,and uses the storage function of the capacitor material to accumulate charge and then release it,so as to improve the output current of the battery.In this paper,an integrated capacitive photoanode is constructed.By adding Ru O₂ to the photoanode,a capacitive photoanode with integrated structure was designed and constructed.The capacitive photoanode consists of Ru O₂ capacitor layer and Ti O₂ photocatalytic layer.The Ti O₂ photocatalytic layer realizes the absorption and conversion of solar energy,while the Ru O₂ capacitor layer plays the role of storing electric energy.The photochemical properties of the capacitive photoanode have been studied experimentally.The surface capacitance of the capacitive photoanode can reach 1040.74 m F cm^-2 at the current density of 0.5 m A cm^-2 due to the photoelectric coupling between the photocatalytic layer and the capacitive layer.In addition,capacitive photoanodes can be charged and discharged continuously for 100 cycles and maintain 89%of the initial capacitance after the cycle.The charge-discharge performance of capacitive photoanode was studied.The discharge current reached 32 m A cm^-2 after photocharging.The results of linear voltammetry show that the photochemical activity of capacitive photoanode is better than that of traditional Ti O₂ photoanode.Finally,the capacitive photoanode was assembled into a full PFC,and its charge-discharge performance was studied.In order to further improve the capacitance performance and reduce the cost,an integrated wood capacitor PFC was designed and constructed using wood as the capacitor electrode.Carbonized wood（CW）electrodes were prepared by carbonizing natural wood.The Mn O₂@CW electrode was prepared by electrodeposition of Mn O₂ pseudocapacitive material onto carbonized wood.The hierarchical porous structure of wood electrode was characterized by morphology and elements.The results of cyclic voltammetry scanning and galvanostatic charge-discharge tests show that the wood electrode has good capacitance performance and excellent electrochemical characteristics.The Mn O₂@CW electrode has a surface capacitance of up to 3774.23 m F cm^-2 at a current density of 1 m A cm^-2.The CW electrode and Mn O₂@CW electrode were used as capacitor electrode to assemble wood capacitor.After dye sensitization,the photoanode was combined with the wood capacitor,and the integrated wood capacitor PFC was successfully prepared.The charging and discharging performance of wood capacitor PFC was studied.The PFC can reach 0.92 V charging voltage after photocharging.And the discharging time of the wood capacitor PFC could reach 714s after the photocharging.