Membraneless Photocatalytic Fuel Cell with Double Photoelectrodes for Simultaneous Electricity Generation and Pollutant Degradation

Environmental pollution and new energy development have become topics of increasing concern. Herein, a visible-light-driven photocatalytic fuel cell (PFC) with double photoelectrodes was constructed for simultaneous electricity generation and pollutant degradation, in which graphitic carbon nitride (g-C3N4) generated on W/WO3 nanorod arrays (W/WNR/g-C3N4) was used as the photoanode and Fe3+-doped CuBi2O4 thin film on indium tin oxide (ITO) conductive glass (ITO/CBFeO) was used as the photocathode. The experimental results showed that the WO3/g-C3N4 Z-scheme structure and one-dimensional WNR rod-like structure could effectively suppress the recombination of photogenerated charge carriers and enable W/WNR/g-C3N4 to present a good photocurrent response under visible light irradiation. The Fermi level mismatch between the W/WNR/g-C3N4 photoanode and ITO/CBFeO photocathode could improve the transfer of photogenerated electrons from the photoanode to the photocathode across the external circuit, enabling the constructed PFC to afford high electricity output and good efficiency for pollutant degradation. The short-circuit current density and maximum power density could reach 620 μA cm−2 and 110 μW cm−2, respectively, while the degradation ratio of oxytetracycline reached 97.6% in 90 min. Therefore, the proposed PFC system provides a new way to generate electric energy and degrade pollutants simultaneously.

Efficient Dye Contaminant Elimination and Simultaneously Electricity Production via a Bi-Doped TiO2 Photocatalytic Fuel Cell

TiO2 develops a higher efficiency when doping Bi into it by increasing the visible light absorption and inhibiting the recombination of photogenerated charges. Herein, a highly efficient Bi doped TiO2 photoanode was fabricated via a one-step modified sol-gel method and a screen-printing technique for the anode of photocatalytic fuel cell (PFC). A maximum degradation rate of 91.2% of Rhodamine B (RhB) and of 89% after being repeated 5 times with only 2% lost reflected an enhanced PFC performance and demonstrated an excellent stability under visible-light irradiation. The excellent degradation performance was attributed to the enhanced visible-light response and decreased electron-hole recombination rate. Meanwhile, an excellent linear correlation was observed between the efficient photocurrent of PFC and the chemical oxygen demand of solution when RhB is sufficient.

Feasibility study of municipal wastewater removal synchronized with electricity generation via solar-driven photocatalytic fuel cell with Bi2WO6/ZnO nanorods array photoanode

The reclamation of energy from municipal wastewater treatment process is highly demanded and could resolve the two most formidable dilemmas of water pollution and energy crisis nowadays. In this study, a photocatalytic fuel cell (PFC) utilizing a Z-scheme heterojunction Bi2WO6/ZnO nanorod arrays (NRAs) photoanode was employed for efficient municipal wastewater treatment and electricity generation simultaneously under sunlight irradiation. Various characterization techniques, including energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), transient photoresponse (TPR), and linear sweep voltammetry (LSV) were used to analyze the physical, chemical and photoelectrochemical characteristics of the as-synthesized photoanode. The results indicated that the Z-scheme heterojunction Bi2WO6/ZnO NRAs exhibited the excellent photocatalytic performance under sunlight irradiation as compared to pristine ZnO NRAs. Ergo, the PFC system achieved complete removal of COD and produced 3.30 μW cm−2, 37.10 μA cm−2 and 563 mV of maximum power density (Pmax ), short-current density (Jsc) and open-circuit voltage (Voc) within 4 h of sunlight irradiation, respectively. The boosted photoactivity was ascribed to the successful formation of the Z-scheme hybridization interface betwixt the Bi2WO6 and ZnO NRAs, that not only enhanced the visible light adsorption of ZnO NRAs, concomitantly significantly accelerated the spatial charge separation and restrained the electron-hole pair recombination.