Photocatalytic Fuel Cell Research Articles

Mechanistic insight into the self-catalyzed degradation of Cu-EDTA in photocatalytic fuel cell coupled with peroxymonosulfate

The performance and mechanism of self-catalyzed degradation of Cu-EDTA in a peroxymonosulfate (PMS)-coupled photocatalytic fuel cell (PFC) are investigated for the first time. By choosing Ca-EDTA and Pb-EDTA as controls for the comparative experiments, it was estimated that the self-catalyzed degradation of Cu-EDTA in the PMS/PFC/sunlight system contributed 41.8 % of its total degradation and 22.6 % of the total maximum output power density. The self-catalyzed degradation of Cu-EDTA via the released Cu2+ increased the contribution of h+, 1O2, and •OH to Cu-EDTA degradation. In solution, Cu2+ could activate PMS via the Cu2+/Cu+ redox cycle. Moreover, partial Cu2+ could be reduced by e− and deposited on photoanode as copper oxides/copper to form a new heterojunction with TiO2-nanotube-arrays, which improved the separation of charge-carriers and redox capacity of the photoanode, thus enhancing the photocatalysis of PFC and photocatalytic activation of PMS. Besides, the self-catalyzed degradation of Cu-EDTA increased the electricity power generation in the PFC by improving the reactivity of the photoanode and reducing the resistance via deposition. This study proposed new insights into the self-catalyzed degradation of metal-complexes in sulfate radical advanced oxidation processes and provided a clean, efficient, and economical way for Cu-EDTA degradation by enhancing this self-catalysis via the PFC.

Enhanced self-biased photocatalytic fuel cell performance by dual-photoelectrode with novel graphene-based substrate for tetracycline photodegradation and electricity production

In this study, a graphene-based dual-photoelectrode photocatalytic fuel cell (PFC) system, incorporating n-type ZnO photoanode and p-type Cu2O photocathode, has been meticulously designed and fabricated to achieve concurrent organic pollutant decomposition and electricity production. The rGO-ZnO｜rGO-Cu2O PFC system displayed superior photoelectrocatalytic performance, surpassing the comparative FTO-based PFC system. Notably, it achieved power density of 22.23 μW cm−2 maximumly, tetracycline hydrochloride (TCH) degradation efficiency of 74.0 % within 120 min, and exhibited long-term stability. This enhanced performance can give the credit to the larger active areas generated by the in-situ growth of photocatalytic materials in layered microstructure of graphene films, as well as the rapid electron transfer within graphene films. This study underscores the potential application of graphene films as electrode substrate materials, and introduces a strategy for achieving the diversification and optimization of electrode substrate material selection, ultimately facilitating the development of more efficient PFC systems.

One-Step Self-Assembled WO3/rGO Microspheres Photoanode Assembled Efficient Photocatalytic Fuel Cells for Simultaneous Organic Pollutant Degradation and Electricity Generation.

Photocatalytic fuel cells (PFCs) present a promising and environmentally friendly approach to simultaneously treat organic pollutants in wastewater and electricity generation. The development of photoanodes with high light absorption and carrier mobility is essential for enhancing the performance of PFCs but remains challenging. Herein, a one-step self-assembly strategy was adopted to develop flower-like WO3/rGO microspheres for PFC devices. Attributed to the abundant surface-active sites, enhanced light harvesting, and efficient separation of photogenerated charge carriers, the WO3/rGO photoanode demonstrated superior rhodamine B (RhB) degradation rate (90% in 2 h), maximum power density (4.74 μW/cm2), and maximum photocurrent density (0.096 mA/cm2), 1.4, 2.4, and 4.0 times higher than the corresponding pure WO3 photoanode, respectively. Density functional theory (DFT) calculations reveal that the built-in electric field formed between the interface of WO3 and rGO promotes the transfer of photogenerated electrons from WO3 to rGO, thus exerting a significant impact on improving the migration and separation of photoinduced charge carriers. Moreover, by combining experimental and theoretical results, a complete PFC operation mechanism for the PFC system was proposed. This study focuses on the strategy of constructing rGO-doped photocatalysts to enhance the interfacial charge transfer mechanism, providing a promising approach for the development of high-performance photoanodes in PFC systems.

Visible-light driven O2-to-H2O2 synchronized activation of peroxymonosulfate in Z-scheme photocatalytic fuel cell for wastewater purification with power generation

Antibiotics are recognized as emerging contaminants with non-biodegradation, complex structures, and abundant chemical energy, which are difficult to treat and recover energy through traditional wastewater treatment processes. A Z-scheme photocatalytic fuel cell (PFC) system, comprising C3N5 and CuO/Cu2O dual-photoelectrodes, has been developed for simultaneous power generation and degradation of antibiotics, such as berberine hydrochloride (BH). Especially, the C3N5 with its suitable energy potential for peroxymonosulfate (PMS) activation is synchronized with CuO/Cu2O, resulting in enhancing the performance of PFC system. Moreover, the interaction between PMS and Cu(I)/Cu(II) active sites on the photocathode can enhance the formation of highly reactive species (HRS) in the PFC-PMS system, thereby improving photocatalytic oxidation performance. Under visible-light illumination for 120 min, PFC-PMS system can rapidly and effectively oxidize BH (ca. 99.2 %, k = 0.0039 min−1) with simultaneous power generation (0.018 mW cm−2). This approach presents a promising approach for both water cleanup and energy reuse applications.

Co2-Fe8-BTC/g-C3N4/Bi2O3/Ti photoanode for visible light responsive photocatalytic fuel cell degradation of rhodamine B and electricity generation

The Co2-Fe8-BTC/g-C3N4/Bi2O3/Ti photoanode with the double Z-type heterojunction was produced by hydrothermal technique and to assemble visible light responsive photocatalytic fuel cell (PFC) with Cu cathode. The synthesized photoanode was characterized by SEM, FT-IR, XPS, XRD and UV–vis DRS analysis. The maximum photocurrent density, maximum power density, and rhodamine B degradation rate of the PFC were 0.53 mA·cm-2, 33.56 μW·cm-2, and 96.89 % (60 min), respectively, which were much higher than these of PFCs with g-C3N4/Bi2O3/Ti photoanode (0.19 mA·cm-2, 11.64 μW·cm-2, 55.37 %, respectively) and Bi2O3/Ti photoanode (0.15 mA·cm-2, 6.63 μW·cm-2, 41.67 %, respectively). The electricity generation performance and rhodamine B degradation of this PFC system is greatly enhanced by the double Z-type heterojunctions of the photoanode among Co2-Fe8-BTC, g-C3N4 and Bi2O3, which accelerates the isolation of photogenerated carriers, and also retains good redox capability, thus obtaining high photocatalytic activity. This work can serve as reference for the design and heterojunction construction of high-efficiency photoanode of PFC with visible light response.

Simultaneous removal of tetracycline hydrochloride and hexavalent chromium by heterogeneous Fenton in a photocatalytic fuel cell system

In this work, a novel double-chamber system (PFC-Fenton), combined photocatalytic fuel cell (PFC) with Fenton, was constructed for tetracycline hydrochloride (TCH) and hexavalent chromium (Cr(VI)) removal and electricity production. Therein, Zn5(OH)6(CO3)2/Fe2O3/BiVO4/fluorine-doped SnO2 (ZIO/BiVO4/FTO) and carboxylated carbon nanotubes/polypyrrole/graphite felt (CCNTs/Ppy/GF) were served as photoanode and cathode, respectively. Under light irradiation, the removal efficiencies of TCH and Cr(VI) with the addition of H2O2 (2 mL) could reach 93.1% and 80.4%, respectively. Moreover, the first-order kinetic constants (7.37 × 10−3 min−1 of TCH and 3.94 × 10−3 min−1 of Cr(VI)) were 5.26 and 5.57 times as much as the absence of H2O2. Simultaneously, the maximum power density could be obtained 0.022 mW/cm2 at a current density of 0.353 mA/cm2. Therein, the main contribution of TCH degradation was ·OH and holes in anode chamber. The synergistic effect of photoelectrons, generated ·O2−, and H2O2 played a crucial role in the reduction of Cr(VI) in cathode chamber. The high-performance liquid chromatography-mass spectrometry indicated that TCH could be partially mineralized into CO2 and H2O. X-ray photoelectron spectroscope and X-ray absorption near-edge structure spectra showed that Cr(VI) could be reduced to Cr(III). After 5 times of cycling, the removal efficiencies of TCH and Cr(VI) were still greater than 70%, indicating the remarkable stability of the PFC-Fenton system. Overall, this system could remove TCH/Cr(VI) and generate power simultaneously without iron sludge formation, demonstrating a promising method to further develop PFC-Fenton technology.

Synthesis, characterization and performance evaluation of a novel flower-like Zn[sbnd]Zr MOF/FeWO4/BiOBr/Ti photoanode with type II heterojunction and visible light response

The performance of a photocatalytic fuel cell (PFC) depends on its photoelectrode. In this work, a novel three-dimensional flower-like hierarchical photoanode ZnZr MOF/FeWO4/BiOBr/Ti was synthesized, characterized and applied in PFC to degrade rhodamine B and generate electricity simultaneously. The characterization results of XRD, SEM, EDS, FI-IR, DRS, and XPS show that the photoanode was successfully prepared. The loading of FeWO4 and ZnZr MOF widened the nanosheet spacing of BiOBr, which enhanced the light absorption intensity, broadened the light absorption band edge from 467.6 nm to 490.2 nm, and increased the photocurrent density from 0.0149 mA/cm2 to 0.156 mA/cm2. The maximum photocurrent density, maximum power density, degradation rate, and FF of the PFC with the prepared photoanode were respectively 0.256 mA·cm−2, 22.65 μW·cm−290.48 % (1 h), and 0.216, which were far higher than those of PFCs with mono and binary photoanodes. The strong photocatalytic performance of the photoanode is attributed to the type II heterojunction formed between BiOBr and FeWO4, which helps to separate electron-hole pairs. The main reactive materials responsible for degrading rhodamine B are h+ and ·O2-. This research provides a new idea for developing an efficient visible light response photoanode.

Improved charge kinetics of BiVO4/MoS2 photoanode by an TiO2 electron transport layer for photocatalytic fuel cell photodegradation and electricity generation

The poor contact between the photocatalyst and the FTO substrate are the main factors lead to the low performance of photocatalytic fuel cell (PFC). Herein, a FTO pre-treated with a TiO2 electron transport layer was used as a substrate for the synthesis of the MoS2/BiVO4/pre-FTO photoanode. The proposed MBV-4/pre-FTO photoanode with its enhances the visible light absorption and effectively delays the recombination of the photoexcited charge. The MBV-4/pre-FTO composite photoanode (6.02 mA/cm2) exhibited a photocurrent density that was 2.2 times higher than that of the BiVO4 photoanode (2.78 mA/cm2). This is attributed to the short charge migration length of the thin MoS2 layer, the fast photoexcited electron transport effect of the TiO2 seed layer, and the heterojunction structure of the proposed photoanode. The DFT calculation result indicated that the TiO2 electron transport layer showed an outstanding photoelectron attractive and transporting effect. The MoS2/Ni foam was employed as the photocathode to establish a mismatched Fermi level for driving PFC. The short-circuit current, open-circuit voltage, and maximum power density of the PFC were 0.578 mA/cm2, 0.632 V, and 0.125 mW/cm2, respectively. The main photodegradation active species are the superoxide anion (∙O2–) and the photoexcited hole (h+), and the degradation efficiency is 61.97 %.

Integrating detection and degradation of bisphenol A by photocatalytic fuel cell-driven photoelectrochemical sensor

To ensure food safety and environmental protection, it is crucial to rapidly identify and remove bisphenol A (BPA), a plasticizer commonly used in the inner lining of food containers and beverage packaging. Here, a photocatalytic fuel cell (PFC)-integrated self-powered photoelectrochemical (PEC) sensor is constructed. Unlike conventional single PEC or PFC sensors, this PFC-integrated PEC sensor relies on not only the difference in Fermi energy levels between photoanode and photocathode but also charge accumulation resulted from the oxidation of BPA by photogenerated holes. Consequently, this sensor achieved a remarkable maximum output power (Pmax) of 8.58 μW cm−2, as well as a high sensitivity, wide linear detection range (0.1–200 μM), low detection limit (0.05 μM), great stability, reproducibility, and real sample detection capability. This work integrates PFC and PEC technologies successfully for the rapid identification and efficient removal of BPA.

Approaches for Enhancing Wastewater Treatment of Photocatalytic Fuel Cells: A Review.

Environmental pollution and energy crises have garnered global attention. The substantial discharge of organic waste into water bodies has led to profound environmental contamination. Photocatalytic fuel cells (PFCs) enabling the simultaneous removal of refractory contaminants and recovery of the chemical energy contained in organic pollutants provides a potential strategy to solve environmental issues and the energy crisis. This review will discuss the fundamentals, working principle, and configuration development of PFCs and photocatalytic microbial fuel cells (PMFCs). We particularly focus on the strategies for improving the wastewater treatment performance of PFCs/PMFCs in terms of coupled advanced oxidation processes, the rational design of high-efficiency electrodes, and the strengthening of the mass transfer process. The significant potential of PFCs/PMFCs in various fields is further discussed in detail. This review is intended to provide some guidance for the better implementation and widespread adoption of PFC wastewater treatment technologies.

Sustainable and Low-Cost Electrodes for Photocatalytic Fuel Cells.

Water pollutants harm ecosystems and degrade water quality. At the same time, many pollutants carry potentially valuable chemical energy, measured by chemical oxygen demand (COD). This study highlights the potential for energy harvesting during remediation using photocatalytic fuel cells (PCFCs), stressing the importance of economically viable and sustainable materials. To achieve this, this research explores alternatives to platinum cathodes in photocathodes and aims to develop durable, cost-effective photoanode materials. Here, zinc oxide nanorods of high density are fabricated on carbon fiber surfaces using a low-temperature aqueous chemical growth method that is simple, cost-efficient, and readily scalable. Alternatives to the Pt cathodes frequently used in PCFC research are explored in comparison with screen-printed PEDOT:PSS cathodes. The fabricated ZnO/carbon anode (1.5 × 2 cm2) is used to remove the model pollutant used here and salicylic acid from water (30 mL, 70 μM) is placed under simulated sunlight (0.225 Sun). It was observed that salicylic acid was degraded by 23 ±0.46% at open voltage (OV) and 43.2 ± 0.86% at 1 V with Pt as the counter electrode, degradation was 18.5 ± 0.37% at open voltage (OV) and 44.1 ± 0.88% at 1 V, while PEDOT:PSS was used as the counter electrode over 120 min. This shows that the PEDOT:PSS exhibits an excellent performance with the full potential to provide low-environmental-impact electrodes for PCFCs.

Dual-functional silicon nanowire arrays-based photocatalytic fuel cell for solar-to-electricity conversion and self-powered glucose detection

Developing a dual-functional photocatalytic fuel cell (PFC) with improved solar-to-electricity energy conversion efficiency and renewable biomass sensitivity performance is of great significance for clean energy conservation and utilization. Herein, a novel PFC device with stable signal output and glucose sensing performance is fabricated, of which polyaniline (PANI) functionalized p-type silicon nanowire arrays (SiNWs) and In2S3 modified n-type SiNWs are utilized as the photocathode and photoanode, respectively. The optimal PFC exhibits excellent cell performance under AM 1.5G illumination with an open circuit voltage of 0.83 V and a high-power density of 163.010 μW cm−2. The PFC also achieves effective glucose detection performance with a low detection limit of 0.998 μM and a broad linear range of 0∼50 mM, as well as excellent selectivity and stability. The enhanced performance is attributed to the efficient carrier separation and charge transfer rate at the interface of the heterojunctions, which is facilitated by the high conductivity of uniform PANI film on the p-SiNWs and S-scheme band alignment formed in the photoanodes. This work opens a new path for improving the energy conversion efficiency in traditional PFCs and offers guidance for sensing strategies toward renewable biomass using PFCs.

Ag nanofilm enhanced S-type Ag@AgCl/tubular g-C3N4/Ti photoanode visible light response photocatalytic fuel cell

In this study, based on Ag@AgCl/tubular g-C3N4 (Ag@AgCl/TCN) composite, Ag nanoparticles were deposited on its surface to form Ag nanofilm enhanced composite through photoreduction of excessive silver nitrate solution to obtain Ag nanofilm Ag@AgCl/TCN photocatalyst. Finally, Ag nanofilm Ag@AgCl/TCN/Ti photoanode was successfully prepared by silica-sol drop-coating method, and assembled with Cu2O/Cu cathode to construct a photocatalytic fuel cell (PFC). Ag nanofilm can not only enhance the light absorption and utilization of Ag@AgCl/TCN/Ti, but also extend its light response wavelength to visible light, and be used as an electron transfer medium to reduce internal resistance. The photocurrent density and the photoconversion efficiency of the Ag nanofilm/Ag@AgCl/TCN/Ti are 8.01 mA·cm−2 and 1.24%, respectively, which are 2.49 and 2.54 times those of the Ag@AgCl/TCN/Ti photoanode, respectively. The first-order kinetic constant and the maximum power density of the Ag nanofilm-coated Ag@AgCl/TCN/Ti-Cu2O/Cu PFC system are 0.064 min−1 and 46.37 μW·cm−2, respectively, which are 1.39 and 1.94 times those of the Ag@AgCl/TCN-Cu2O/Cu PFC system, respectively. In addition, it degraded more than 95% of rhodamine B, 72.68% of tetracycline and 54.25% of bisphenol A within 60 min. The excellent performance of Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu is due to the strengthening of Ag nanofilm and the formation of S-type heterojunctions between AgCl and TCN. Free radicals (•Cl, h+, •OH, •O2-) and non-radicals (1O2) are involved in the degradation reaction of RhB degradation. It is worth noting that 6% Ag nanofilm/Ag@AgCl/TCN/Ti-Cu2O/Cu has a positive effect on the production of •O2-, and its output is approximately 1.89 times that of the Ag@AgCl/TCN/Ti-Cu2O/Cu. A series of material characterization experiments have been completed and possible mechanisms of operation have been proposed. This study provides a new scheme for the design and preparation of high-efficiency photoanode of PFC.

Enhanced Power Generation Using a Dual-Surface-Modified Hematite Photoanode in a Direct Glyphosate Photo Fuel Cell.

Given the current and escalating global energy and environmental concerns, this work explores an innovative approach to mitigate a widely employed commercial herbicide using a direct glyphosate (Gly) photocatalytic fuel cell (PFC). The device generates power continuously by converting solar radiation, degrading and mineralizing commercial glyphosate-based fuel, and reducing sodium persulfate at the cathode. Pristine and modified hematite photoanodes were coupled to Pt/C nanoparticles dispersed in a carbon paper (CP) support (Pt/C/CP) dark cathode by using an H-type cell. The Gly/persulfate PFC shows a remarkable current and power generation enhancement after dual-surface modification of pristine hematite with segregated Hf and FeNiOx cocatalysts. The optimized photoanode elevates maximum current density (Jmax) from 0.35 to 0.71 mA cm-2 and maximum power generation (Pmax) from 0.04 to 0.065 mW cm-2, representing 102.85 and 62.50% increase in Jmax and Pmax, respectively, as compared to pristine hematite. The system demonstrated stability over a studied period of 4 h; remarkably, the photodegradation of Gly proved substantial, achieving ∼98% degradation and ∼6% mineralization. Our findings may significantly contribute to reducing Gly's environmental impact in agribusiness since it may convert the pollutant into energy at zero bias. The proposed device offers a sustainable solution to counteract Gly pollution while concurrently harnessing solar energy for power generation.

Evaluation of a novel continuous baffled photo-reactor for tetracycline degradation and simultaneous electricity production in photocatalytic fuel cell

Photocatalytic fuel cell (PFC) systems can be a new generation of energy production by simultaneously producing electricity and removing organic pollutants from aqueous solutions. A baffling photoreactor is developed for application in a PFC, and the continuous system consists of a light-responsive photoanode (ZnO/Bi2MoO6/MIL-101; ZnO/Bi2MoO6; ZnO) and a photocathode (Cu/CuO/Cu2O). A response surface method (RSM) is presented to characterize the process factors (pH, immobilized catalyst dosage (mg/cm2), and tetracycline concentration (ppm)) on the performance of a reactor designed to optimize degradation efficiency and maximum power generation. The optimal conditions are determined at pH = 7, Catalyst dosage = 0.87 mg/cm2, and tetracycline concentration = 80 ppm. In optimal conditions, other parameters for degradation efficiency (88.8%), open circuit voltage (1.03 V), short circuit current (2.5 mA/cm2), and maximum power generation (0.87 mW/cm2) are obtained. The performance of different photoanodes by linear sweep voltammetry shows a current density of 2.5 mA/cm2 for ZnO/Bi2MoO6/MIL-101, which is 7.8 and 1.8 times higher than ZnO and ZnO/Bi2MoO6 photoanodes, respectively. The flow regime is determined by residence time distribution (RTD) in the novel reactor with the experimental data of 6 tanks-in-series.

BaTiO3/Fe2O3/MoS2/Ti photoanode for visible light responsive photocatalytic fuel cell degradation of rhodamine B and electricity generation

In order to improve the performance of visible light-responsive photocatalytic fuel cell (PFC), BaTiO3/Fe2O3/MoS2/Ti photoanode was prepared by a secondary hydrothermal and silica sol drop-coating method in this study, and assembled with Cu cathode to construct PFC. The composition, morphology, surface elements and chemical states, light absorption characteristics, rhodamine B degradation, electrochemical performance and stability of 10 % BaTiO3/Fe2O3/MoS2/Ti photoanode were studied. The rhodamine B degradation rate, maximum photocurrent density, and maximum power density of the PFC with 10 % BaTiO3/Fe2O3/MoS2/Ti photoanode are 94.23 %, 0.20 mA•cm−2 and 10.46 μW·cm−2, respectively. The excellent performance of the PFC is due to the internal electric field formed by the spontaneous polarization of the ferroelectric BaTiO3, which significantly promotes the charge transfer between MoS2 and Fe2O3, and realizes the spatial separation of photogenerated electrons and holes, thereby reducing the recombination of e−-h+ pairs and ultimately improving the photoelectricity and photocatalytic performance. This study provides an important reference for ferroelectric materials to promote the separation of photogenerated carriers in visible light responsive PFC.

Self-breathing strategy-enabled high-performance self-powered photoelectrochemical sensing by integrating with a perovskite Ag3BiO3/Ti3C2 plasmonic heterojunction.

An innovative photocatalytic fuel cell (PFC)-based self-powered system was developed by integrating the perovskite Ag3BiO3/Ti3C2 MXene plasmonic heterojunction with a self-breathing strategy, which was beneficial for developing high-performance self-powered photoelectrochemical biosensors.

Photocatalytic fuel cell assisted by Fenton-like reaction for p-Chloronitrobenzen degradation and electricity production through S-scheme heterojunction C3N5 modified TNAs photoanode: Performance, DFT calculation and mechanism

Photocatalytic fuel cell (PFC) is a promising technology to recover usable energy from wastewater through the degradation of pollutants, whereas the complex preparation procedures and high photogenerated carrier recombination efficiency of photoanode remains an urgent challenge to improve the PFC performance. Herein, PFC with S-scheme heterojunction C3N5/TNAs photoanode assisted by Fenton-like reaction (C3N5/TNAs-PFC-Fenton) system was built for p-Chloronitrobenzene degradation and electricity production. The working function confirmed the band bending of C3N5 and TNAs, and density functional theory calculations indicated the formation of internal electric field at heterojunction interface of C3N5 and TNAs, which promoted visible-light absorption capacity and charge transfer property of C3N5/TNAs photoanode. The incorporation of Fenton-like reaction into C3N5/TNAs-PFC-Fenton system could effectively enhance p-Chloronitrobenzene degradation and electricity production by participating in free radical chain reaction and stimulating electron transfer. The radical trapping experiments confirmed that •OH and photogenerated electron were main reactive species, and photogenerated hole, •O2− and 1O2 were also participated in p-Chloronitrobenzene degradation. The p-Chloronitrobenzene degradation pathway was interpreted and the overall toxicity of p-Chloronitrobenzene was relieved after treatment in C3N5/TNAs-PFC-Fenton system. The C3N5/TNAs-PFC-Fenton system exhibited fine universality for degradation of organic pollutants and electricity production.

Incorporating photocatalytic fuel cell with dual S-scheme CuBi2O4/Bi2WO6/ZnO NRA photoanode for energy recuperation from municipal wastewater treatment under sunlight

Photocatalytic fuel cell (PFC) utilized the chemical energy contained in the molecules by combining photocatalytic treatment of wastewater with fuel cell electrochemical reaction. Herein, a PFC system with a novel dual S-scheme heterojunction CuBi2O4/Bi2WO6/ZnO nanorod array (CBO/BWO/ZnO NRA) composite photoanode was first constructed for municipal wastewater treatment accompanied with electricity generation under direct sunlight. The introduction of CBO and BWO not only contributed to the narrowing of the band gap which enabled the ZnO NRA to utilize sunlight more efficiently, but also led to the excellent electron-hole segregating capability. The 10% CBO/BWO/ZnO NRA composite photoanode achieved a significantly ameliorated electrical power with maximum power density of 7.707 µW/cm2, which was superior to those pristine ZnO NRA and BWO/ZnO NRA binary materials. The composite photoanode was then tested for its mineralization activity in the municipal wastewater and 98.4% of COD removal was acquired within 90 min. The main attribution that conducive to its spectacular performance in municipal wastewater treatment came from the one-dimensional nanorod array architecture along with the synergistic relation among the three efficient components in the CBO/BWO/ZnO NRA heterojunction that can effectively hinder the charge carrier recombination rate and facilitated a good route for electron transport. The composite photoanode also manifested good stability in five cyclic runs. The dual S-scheme CBO/BWO/ZnO NRA enabled the free active species partook in the photoelectrocatalytic reaction and the working principle of PFC system was also speculated. Additionally, phytotoxicity findings signified that the comprehensive toxicity of municipal wastewater was eliminated after PFC treatment.

Boosting Carbon Dioxide Reduction in a Photocatalytic Fuel Cell with a Bubbling Fluidized Cathode: Dual Function of Titanium Carbide.

Photoelectrochemical reduction of carbon dioxide (CO2) is a promising avenue to realize resourceful utilization of carbon dioxide and mitigate the energy shortage. Herein, a photocatalytic fuel cell with a bubbling fluidized cathode (PFC-BFC) is proposed to increase the performance of the photocatalytic CO2 reduction reaction (CO2RR). Titanium carbide (Ti3C2) is first used as a fluidized cathode catalyst with the dual features of superior capacitance and high CO2RR catalytic activity. Compared with the conventional PFC system, the as-proposed PFC-BFC system exhibits a higher gas production performance. Particularly, the generation rate and Faraday efficiency for CH4 production reach to 37.2 μmol g-1 h-1 and 72%, which are 10.9 and 6.5 times higher than that of the conventional PFC system, respectively. The bubbling fluidized cathode allows a rapid electron transfer between catalysts and the current collector and an efficient diffusion of catalysts in the whole solution, thus remarkably increasing the effective reaction area of the CO2RR. In addition, the fluidized reaction mechanism of charging/discharging-coupled CO2RR is investigated. Significantly, a magnified PFC-BFC system is designed and exhibits a similar gas generation rate compared to that of the small-scale system, indicating a good potential of scaling up in the industry applications. These results demonstrated that the proposed PFC-BFC system can maximize the utilization of catalyst active sites and enhance the reaction kinetics, providing an alternative design for the application of CO2RR.