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Heterostructure photocatalytic materials with a high surface area have garnered significant attention in recent years. In this investigation, we successfully synthesized g-C 3 N 4 /TiO 2 tubes using an enhanced impregnation-calcination method. The photocatalytic efficiency of the composite tubes was evaluated by examining the degradation of tetracycline hydrochloride (TCH) solution, revealing a photocatalytic degradation rate 3.7 times and 8.0 times higher than that of pure TiO 2 and g-C 3 N 4 when subjected to simulated sunlight. The enhanced photocatalytic performance can be ascribed to the expanded specific surface area and enhanced separation rate of photo-generated charge carriers. Density functional theory (DFT) calculations and trapping experiments revealed a possible photogenerated electrons transfer pathway in the degradation process of TCH. The photocatalytic fuel cell (PFC) system composed of the g-C 3 N 4 /TiO 2 tubes demonstrated remarkable performance in the concurrent degradation of TCH and electricity generation when being exposed to light. It achieved a short circuit current density of 26.9 mA/g/cm2 and a power density of 5.51 mW/g/cm2. The present study offers a cost-effective approach for both organic waste treatment and electrical power generation. [ABSTRACT FROM AUTHOR]

This work reports a novel TiO2/g-C3N4 photoanode-based photocatalytic fuel cell (PFC) designed to convert chemical energy from simulated wastewater. The g-C3N4 modified TiO2 nanorod was successfully synthesized by a facile hydrothermal method. The results indicated that the maximum photocurrent density reached 2.44 mA cm-2 at 1.23 V vs. RHE by 1.167 g L-1 g-C3N4 loaded TiO2 composite. On the basis of analysis, the photoelectrochemical mechanism of the composite photoanode was proposed. This mainly demonstrated that the composite photoanode increases the electron donor density and boosts charge separation efficiency. In addition, the power density and hydrogen production of the proposed PFC were enhanced by 5.37 and 1.49 times compared to TiO2 photoanode-based PFC. To find the origins of the excellent performance of PFC, the influence of the organic compounds were investigated. The ESR measurement results indicated that the organic matter was captured by the photoexcited holes directly to facilitate the charge separation. The achieved power density and hydrogen production of 0.14 mW cm-2 and 21.60 μmol h-1 cm-2 were measured using RhB as the model pollutant, which was 2.42 and 1.23 times higher than the experiments with PBS electrolyte. This study proposed a novel PFC system converts the organic pollutant to the hydrogen and the electricity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A single-chamber photocatalytic fuel cell (PFC) employing a TiO2/CuS photocathode and CdS/TiO2 photoanode is designed for the simultaneous degradation of a model organic pollutant and electricity generation. The Fermi levels of the TiO2/CuS photocathode (p-type semiconductor) and CdS/TiO2 photoanode (n-type semiconductor)—residing in the CuS valence band and anodic TiO2 conduction band, respectively—create a favorable internal bias between the photoelectrodes. The presence of anodic CdS and cathodic TiO2 enhances electron–hole separation, thereby improving cell performance. Characterized by XRD and HRTEM, the structural analysis confirms the hexagonal crystal structure for both CdS and CuS, while TiO2 exhibits a tetragonal crystal system. These synthesized photoelectrodes were evaluated in a PFC operating with 10% volumetric ethanol fuel, 0.2 M KOH electrolyte, and 6500 Lux illumination from two compact fluorescent lamps. The achieved maximum current density (ISC), potential (VOC), and power density (PMAX) were 136.6 µA cm−2, 0.779 V, and 43.2 µW cm−2, respectively, indicating promising cell performance. Furthermore, the study suggests that augmenting light intensity, electrolyte and fuel concentration, optimizing solution pH, and utilizing simple organic fuels significantly enhance electricity production and overall cell efficiency. [ABSTRACT FROM AUTHOR]

In a dual-chamber photocatalytic fuel cell device, polyvinyl alcohol degradation and H2 evolution were concurrently achieved. The setup involved commercial P25 as the photoanode and Ag@Fe2O3 nanoparticles as the cathode. Additionally, the feasibility of a Fenton-like reaction in the cathode, utilizing Fe2+ ions and pumped O2, was demonstrated. Different cathode materials, polyvinyl alcohol types, and pH values' effects were assessed on device performance. Quenching tests highlighted photoinduced holes (h+) and OH· radicals as pivotal contributions to polyvinyl alcohol degradation. Long-term stability of the device was established through cycling experiments. [ABSTRACT FROM AUTHOR]

A series of ZnO/ZnWO4 nanocomposites with different ZnWO4 content, are electrochemically synthesized under pulse alternating current starting from ZnO and WO3 nanopowders. A complex of physicochemical methods (X-ray diffraction analysis, Raman spectroscopy, transmission electron microscopy, energy dispersive X-ray microanalysis) was used to study the composition and structural characteristics of the obtained materials. The nanocomposite with optimal composition (ZnWO4 ~6%) was used as a photoanode material for a flow photocatalytic fuel cell with sulfate electrolyte added with organic and inorganic fuel. The maximum values of Eoc (850 mV) and Pmax (85.8 μW/cm2) are achieved using Na2SO4 with the addition of glucose as a fuel. [ABSTRACT FROM AUTHOR]

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.

Attributable to the prosperous production growth of palm oil in Malaysia, the generated palm oil mill effluent (POME) poses a high threat owing to its highly polluted characteristic. Urged by the escalating concern of environmental conservation, POME pollution abatement and potential energy recovery from the effluent are flagged up as a research topic of interest. In this study, a cutting-edge photocatalytic fuel cell (PFC) system with employment of ZnO/Zn nanorod array (NRA) photoanode, CuO/Cu cathode, and persulfate (PS) oxidant was successfully designed to improve the treatment of POME and simultaneous energy production. The photoelectrodes were fabricated and characterized by field emission scanning electron microscopy with energy (FESEM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and Brunauer, Emmett, and Teller analysis (BET). Owing to the properties of strong oxidant of PS, the proposed PFC/PS system has exhibited exceptional performance, attaining chemical oxygen demand (COD) removal efficiency of 96.2%, open circuit voltage (Voc) of 740.0 mV, short circuit current density (Jsc) of 146.7 μA cm−2, and power density (Pmax) of 35.6 μW cm−2. The pre-eminent PFC/PS system performance was yielded under optimal conditions of 2.5 mM of persulfate oxidant, POME dilution factor of 1:20, and natural solution pH of 8.51. Subsequently, the postulated photoelectrocatalytic POME treatment mechanism was elucidated by the radical scavenging study and Mott–Schottky (M-S) analysis. The following recycling test affirmed the stability and durability of the photoanode after four continuous repetition usages while the assessed electrical energy efficiency revealed the economic viability of PFC system serving as a post-treatment for abatement of POME. These findings contributed toward enhancing the sustainability criteria and economic viability of palm oil by adopting sustainable and efficient POME post-treatment technology. [ABSTRACT FROM AUTHOR]

High-efficiency photoelectrode played a significant role in photocatalytic fuel cell (PFC) systems. In this study, a zinc-based metal-organic framework modified by carbon quantum dots (N-Zn-MOF/CQDs) and the BiVO 4 were respectively presented as the photocathode and photoanode of the PFC system toward Cr(Ⅵ) reduction. Various analytical techniques were utilized to characterize the physicochemical, optical and photoelectrochemical properties of the as-prepared samples. With the addition of CQDs, the visible-light response and charge separation rate were remarkably enhanced. In the PFC system, the circuit current density of 58.04 mA cm−2 and max power density of 1.35 mW cm−2 were achieved, which was superior to other reported PFC systems. Under optimized conditions, 100% Cr(Ⅵ) can be removed within 120 min of visible-light illumination. This work provided a new method to decorate the zinc-based metal−organic framework cathode to dramatically improve the photocatalytic performance. • A novel N-Zn-MOF/CQDs photocathode was successfully constructed. • The introduction of CQDs enhanced visible-light response and charge separation rate. • The photocatalytic fuel cell was built with the fabricated N-Zn-MOF/CQDs. • The PFC showed higher power density and removal efficiency for Cr(VI). [ABSTRACT FROM AUTHOR]

Photocatalytic fuel cells (PFCs) need to operate under ultraviolet light, and the application conditions are greatly limited. Therefore, developing and utilizing new systems that adsorb visible light is critical. Molybdenum disulfide (MoS2) nanomaterials have wide bandgaps, strong visible light absorption capacities, and abundant catalytic active sites. In this study, the photocathode MoS2/graphene oxide (GO) was prepared by coupling it with graphene oxide by using the mechanical oscillation method (MoS2/GO-MO) and the hydrothermal synthesis method (MoS2/GO-TH). In addition, a PFC was constructed to treat nitrogenous wastewater. According to an X-ray diffractometer and electron microscope, regarding the characterization analysis and electrochemical analysis of the materials, the system with MoS2/GO-TH electrode had the best performance with the largest output voltage, the smallest ohmic loss during the reaction, the best oxidation-reduction capacity, and the highest ammonia nitrogen removal rate. The optimal removal rate might reach up to 96.0%. On this basis, the denitrification mechanism was explored, and the results revealed that oxygen in the PFC system was the decisive factor and that there were multiple plausible reaction paths during the reaction process. [ABSTRACT FROM AUTHOR]

Cathode in photocatalytic fuel cell (PFC) plays a crucial role in degradation of organic contaminants. In this study, synthesized copper oxide (CuO) was loaded on carbon plate and used as photocathode in PFC for degradation of synthetic azo dye Reactive Black 5 (RB5) and real textile wastewater. Morphology and structural phase of the synthesized CuO were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Several operating parameters had been investigated such as light irradiation, initial dye concentration, and pH of azo dye solution within 6 h of irradiation time. The lowest initial concentration of RB5 (10 mg L−1) achieved 100% color removal compared to the highest initial concentration (40 mg L−1) which only achieved 77.1% color removal within 6 h of irradiation time. The influence of external resistance was significant in electricity generation but trivial in dye degradation efficiency. The external resistance of 6000 Ω yielded highest maximum power density, with Pmax of 0.2631 μW cm−2, followed by 1000 Ω (0.2196 μW cm−2) and 8000 Ω (0.1587 μW cm−2), respectively. The real textile wastewater with dilution ratio (DR) 1:6 yielded the highest energy conversion efficiency, η (3.62%), followed by DR 1:4 (3.19%) and DR 1:2 (1.96%), respectively. [ABSTRACT FROM AUTHOR]

Photocatalytic fuel cell (PFC) was employed to provide renewable power sources to photoelectro-Fenton (PEF) process to fabricate a double-chambered hybrid system for the treatment of azo dye, Amaranth. The PFC-PEF hybrid system was interconnected by a circuit attached to the electrodes in PFC and PEF. Circuit connection is the principal channel for the electron transfer and mobility between PFC and PEF. Thus, different circuit connections were evaluated in the hybrid system for their influences on the Amaranth dye degradation. The PFC-PEF system under the complete circuit connection condition attained the highest decolourization efficiency of Amaranth (PFC: 98.85%; PEF: 95.69%), which indicated that the complete circuit connection was crucial for in-situ formation of reactive species in dye degradation. Besides, the pivotal role of ultraviolet (UV) light irradiation in the PFC-PEF system for both dye degradation and electricity generation was revealed through various UV light–illuminating conditions applied for PFC and PEF. A remarkable influence of UV light irradiation on the production of hydrogen peroxide and generation and regeneration of Fe2+ in PEF was demonstrated. This study provided a comprehensive mechanistic insight into the dye degradation and electricity generation by the PFC-PEF system. [ABSTRACT FROM AUTHOR]

In order to solve the rapid recombination of electron–hole pairs, limited optical response range, and single electron and hole transmission path, polydopamine (PDA)/WO3 and TiO2 composite (PDA-11.5%/WO3/TiO2/Ti) photoanode was prepared. Its maximum photocurrent density is 2.03 mA·cm−2 at 1.1 V (vs. SCE), which is 1.47 times higher than that of WO3/TiO2/Ti. The maximum power density, photocurrent density, and Rhodamine B degradation rate of the photocatalytic fuel cell (PFC) with PDA-11.5%/WO3/TiO2/Ti photoanode were 18.68 μW·cm−2, 0.18 mA·cm−2, and 84.6%, respectively. Its excellent performance is mainly due to the good carrier mobility of PDA and the stepped heterojunction structure formed by PDA-11.5%/WO3/TiO2/Ti so that photogenerated electrons and holes gather in the conduction bands of WO3 and HOMO of PDA, respectively. This not only expands the light absorption range and improves the light absorption intensity but also promotes the separation of electron–hole pairs and finally significantly enhances the Rhodamine B degradation and power generation performance of PFC. [ABSTRACT FROM AUTHOR]

Biochar has been obtained by pyrolysis of spent malt rootlets under limited oxygen supply and further activated by mixing with KOH and pyrolyzed again at high temperature. The total specific surface area of such activated biochar was 1148 m2 g−1, while that of micropores was 690 m2 g−1. This biochar was used to make a functional electrode by deposition on carbon cloth and was combined with a photoelectrochemical cell. The biochar electrode functioned as a supercapacitor in combination with the electrolyte of the cell, reaching a specific capacity of 98 Fg−1, and it was capable of storing charges generated by the cell, proving current flow both under illumination and in the dark. The same electrode could be used as an air-cathode providing oxygen reduction functionality and thus demonstrating interesting electrocatalyst properties. [ABSTRACT FROM AUTHOR]

In order to inhibit rapid recombination of electron–hole pairs of photoanode and expand its light response wavelength, PPy-14%/WO3/TiO2/Ti photoanode was prepared. The maximum photocurrent density is 2.31 mA·cm−2, which is 1.76 times higher than that of WO3/TiO2/Ti at 1.1 V (vs. SCE). The maximum power density, phontocurrent density and Rhodamine B degradation rate of photocatalytic fuel cell (PFC) with PPy-14%/WO3/TiO2/Ti photoanode and Cu cathode are 25.48 μW·cm−2, 0.25 mA·cm−2 and 88.5%, respectively. The excellent performance is mainly due to the good carrier migration rate of PPy and the synergistic effect of PPy/WO3/TiO2/Ti ternary hybrid electrode, so that photogenerated electrons and holes can accumulate in the conduction band of WO3 and HOMO of PPy, respectively. This not only expands the light absorption range and enhances the light absorption intensity, but also improves the separation of electron–hole pairs, and finally significantly enhances the Rhodamine B degradation and electricity generation performance of PFC. In order to inhibit rapid recombination of electron–hole pairs of photoanode and expand its light response wavelength, PPy-14%/WO3/TiO2/Ti photoanode was prepared. The excellent performance is mainly due to the good carrier migration rate of PPy and the synergistic effect of PPy/WO3/TiO2/Ti ternary hybrid electrode, so that photogenerated electrons and holes can accumulate in the conduction band of WO3 and HOMO of PPy, respectively. [ABSTRACT FROM AUTHOR]

To enhance dye removal and energy recovery efficiencies in single-pair electrode photocatalytic fuel cell (PFC-AC), dual cathodes PFC (PFC-ACC) and dual photoanodes PFC (PFC-AAC) were established. Results revealed that PFC-AAC yielded the highest decolorization rate (1.44 h−1) due to the promotion of active species such as superoxide radical (•O2−) and hydroxyl radical (•OH) when the number of photoanode was doubled. The results from scavenging test and UV-Vis spectrophotometry disclosed that •OH was the primary active species in dye degradation of PFC. Additionally, PFC-AAC also exhibited the highest power output (17.99 μW) but the experimental power output was much lower than the theoretical power output (28.24 μW) due to the strong competition of electron donors of doubled photoanodes to electron acceptors at the single cathode and its high internal resistance. Besides, it was found that the increments of dye volume and initial dye concentration decreased the decolorization rate but increased the power output due to the higher amount of sacrificial agents presented in PFC. Based on the abovementioned findings and the respective dye intermediate products identified from gas chromatography-mass spectrometry (GC-MS), the possible degradation pathway of RR120 was scrutinized and proposed. [ABSTRACT FROM AUTHOR]

In order to enhance the photoelectric conversion efficiency of a photoanode and broaden its light absorption range, a ZnIn2S4/UiO-66/TiO2/Ti composite photoanode was developed. The maximum photocurrent density of the prepared photoanode is 2.56 mA cm−2 at 1.2 V (versus SCE), which is 1.79 times higher than that of ZnIn2S4/TiO2/Ti. The rhodamine B (RhB) removal rate, short-circuit current density and maximum power density of a photocatalytic fuel cell (PFC) constructed with the ZnIn2S4/UiO-66/TiO2/Ti photoanode and a Cu cathode are 98.01%, 0.22 mA cm−2 and 16.97 μW cm−2 respectively. The enhancement of the PFC performance is mainly attributed to the extremely good energy band matching and nano-size interface contact between ZnIn2S4 and UiO-66. The existence of UiO-66 can be as an electronic transmission bridge, which not only facilitates the rapid transfer and utilization of photogenerated electrons, but also improves the adsorption ability of the photoanode for RhB molecules. [ABSTRACT FROM AUTHOR]

The use of a gas diffusion photoanode for a photocatalytic fuel cell is promising to simultaneously degrade VOCs and generate electricity. However, conventional gas-diffusion photoanode faces the issues of inefficient solar energy utilization and serious electron-hole recombination. Herein, a visible-light-responsive gas-diffusion g-C 3 N 4 /TiO 2 heterojunction photoanode is developed for simultaneous degradation of toluene and generation of electricity. In addition to the intrinsic feature of reduced mass transfer resistance of VOCs to the photocatalytic surface, such a gas-diffusion photoanode not only extends the photo-response spectrum, but also enhances charge separation. Accordingly, the photocatalytic fuel cell with the newly-developed photoanode demonstrates superior discharging performance and toluene removal efficiency over the gas-diffusion TiO 2 and g-C 3 N 4 photoanodes. The maximum power density achieved by the gas-diffusion g-C 3 N 4 /TiO 2 heterojunction photoanode is 0.0375 mW/cm², while the maximum toluene removal efficiency reaches 43.8 %. This study has promoted the development of photocatalytic fuel cells for the degradation of VOCs and electricity generation. • Gas-diffusion g-C3N4/TiO2 heterojunction photoanode is developed. • Visible-light response is enabled and charge separation is enhanced. • Toluene degradation and electricity generation are simultaneously enhanced. [ABSTRACT FROM AUTHOR]

[Display omitted] • The MoS 2 /BiVO 4 /pre-FTO-MoS 2 /Ni foam PFC was constructed for the first time. • The TiO 2 electron transport layer significantly facilited the charge transfer. • The 2D MoS 2 shortened photogenerated electron migration pathway. • MoS 2 /Ni foam served as the photocathode. • The degradation efficiency was strongly affected by h+ and O2–. 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 TiO 2 electron transport layer was used as a substrate for the synthesis of the MoS 2 /BiVO 4 /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 BiVO 4 photoanode (2.78 mA/cm2). This is attributed to the short charge migration length of the thin MoS 2 layer, the fast photoexcited electron transport effect of the TiO 2 seed layer, and the heterojunction structure of the proposed photoanode. The DFT calculation result indicated that the TiO 2 electron transport layer showed an outstanding photoelectron attractive and transporting effect. The MoS 2 /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 %. [ABSTRACT FROM AUTHOR]

Self-powered sensors have the advantages of no external power supply, energy conversion in the environment and easy miniaturization, making it an attractive choice for building implantable, wearable and portable devices. However, it is difficult to sensitively detect low abundance targets owing to their poor output performance and interference from complicated settings. Herein, a new photocatalytic fuel cell-based self-powered electrochemical biosensor (PFC-SPEB) was proposed for the detection of p53 gene by combining high photocatalytic performance In 2 S 3 and CuInS 2 with magnetic nanobeads-assisted signal amplification strategy. In 2 S 3 photoanode and CuInS 2 photocathode were combined to form a dual photoelectrode system with an open-circuit potential up to 705.9 mV, which improved the photoelectric conversion efficiency by 1.4–6.9 folds compared with that of single photoelectrode system. Furthermore, the enzyme-assisted signal amplification strategy made a small number of p53 genes trigger the creation of abundant double-stranded DNA (dsDNA). Finally, manganese porphyrin was inserted into dsDNA to stimulate precipitation reactions on surfaces of the photoanode, leading to a sharp drop of signal. The constructed PFC-SPEB exhibited a wide linear detection range from 10 fM to 10 nM with a low detection limit of 1.40 fM, providing new creative inspiration for constructing SPEB for bioanalysis and clinical diagnostics. [Display omitted] • A novel SPEB was successfully developed by the combination of PFC with MBs-assisted signal amplification strategy. • Compared with single photoelectrode system, dual photoelectrode PFC-SPEB greatly improved output signal up to 705.9 mV. • The MBs-assisted SPEB enabled sensitive detection of p53 gene with a detection limit of 1.40 fM. [ABSTRACT FROM AUTHOR]

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, Zn 5 (OH) 6 (CO 3) 2 /Fe 2 O 3 /BiVO 4 /fluorine-doped SnO 2 (ZIO/BiVO 4 /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 H 2 O 2 (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 H 2 O 2. 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 ·O 2 −, and H 2 O 2 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 CO 2 and H 2 O. 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. • An eco-friendly system was proposed coupling PFC and heterogeneous Fenton reaction. • This system could remove tetracycline hydrochloride and Cr(VI) simultaneously. • Electricity (0.022 mW/cm2) could be generated during the removal of pollutants. • h+ and ·OH were effective for TCH; e−, ·O 2 −, and H 2 O 2 were responsible for Cr(VI). • After 5 cycles, the removal efficiencies were still maintained at about 70%. [ABSTRACT FROM AUTHOR]

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 WO 3 /rGO microspheres for PFC devices. Attributed to the abundant surface-active sites, enhanced light harvesting, and efficient separation of photogenerated charge carriers, the WO 3 /rGO photoanode demonstrated superior rhodamine B (RhB) degradation rate (90% in 2 h), maximum power density (4.74 μW/cm 2 ), and maximum photocurrent density (0.096 mA/cm 2 ), 1.4, 2.4, and 4.0 times higher than the corresponding pure WO 3 photoanode, respectively. Density functional theory (DFT) calculations reveal that the built-in electric field formed between the interface of WO 3 and rGO promotes the transfer of photogenerated electrons from WO 3 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.

Technological advancement is accompanied by excessive consumption of fossil fuels and affluent uses of chemical substances in many sectors, including transportation and manufacturing companies, and so on. Being an exhaustible resource, the excessive use of fossil fuels and of chemical substances may lead to a serious energy crisis in the long run, and it may additionally impose environmental pollution. Attempts have been made in the solution of such serious issues from every nook and corner. Nonetheless, no method has been found to be a panacea in waste water treatment and subsequent beneficiaries. One of the attempts in the solution to such issues is the application of photocatalytic technology, which could serve as a dual function in environmental remediation and clean energy production. A photocatalytic fuel cell is a tool developed for the recovery of energy from organic wastes. A rational cell construction needs the fabrication of photoelectrodes, the design of a photoanode and a photocathode chamber, in addition to an ion-transport membrane for pollution treatment and electricity generation. In this review, comprehensive fundamental assessments and recent developments in the design of photocatalytic fuel cells, their applications, future prospects, and challenges are covered. [ABSTRACT FROM AUTHOR]

Organics bring great challenge on uranium reduction due to the formation of stubborn complexes between uranyl ions (UO 2 2+) and organics. Herein, we developed an effective strategy to synchronously degrade organics and extract uranium from complicated radioactive wastewater, accompanied with electricity generation, by a novel self-driven photocatalytic fuel cell (NSPFC) system, in which a three-dimensional (3D) Co/N-doped carbon nanoplate array (Co-N-C/CF) decorated carbon fiber is employed as the cathode for highly efficient UO 2 2+ reduction. Compared to pure CF, the optimized Co-N-C/CF cathode increases the rate constants (k) by 9 and 9.1 times for UO 2 2+ and organic elimination, respectively, and improves electricity output by 2 times (P max , 1180 μW/cm2). This improvement should be ascribed to the 3D morphology of Co-N-C/CF that provided plenty of surface area for U(VI) reduction, and the doping of N and Co, which effectively increased the U(VI) adsorption sites and optimized the electron behavior on the cathode, respectively. These features endow the NSPFC system with excellent adaptability in treating complex radioactive wastewater with a wide range of pollutant concentration, pH, co-existed ions, pollutant organics and natural organic matters. Fascinating activity is also achieves in treating polluted seawater or under real sunlight illumination. This work not only provides a outstanding nanostructured cathode for uranium reduction but also suggests a charming system to resourcefully treatment of radioactive wastewater or polluted water bodies. A 3D MOF derived Co/N-codoped carbon nanoplate array cathode was synthesized and applied in a novel self-driven photocatalytic fuel cell system for simultaneously degrading organics, recycling uranium, and generating electricity from complex radioactive wastewater under sunlight irradiation. [Display omitted] • A NSPFC is proposed by using a Co-N-C/CF cathode and a monolithic photoanode of TNR-SC. • NSPFC has excellent uranium recycle, organic degradation and electricity generation properties. • Co/N co-doping significantly enhanced the photoelectric properties of NSPFC. • The enhancement mechanism of Co and N is revealed by DFT calculations. • Excellent performance is achieved in a wide wastewater condition or under real sunlight. [ABSTRACT FROM AUTHOR]

• A novel flower-like Zn Zr MOF/FeWO 4 /BiOBr/Ti photoanode was prepared and applied to PFC. • BiOBr combined with FeWO 4 to form type II heterojunction to improve the redox ability. • The introduction of Zn Zr MOF with special selectron transfer mode accelerated the electron transfer. • The RhB degradation rate, P max , J sc , and FF were 90.48 %, 22.65 μW/cm-2, 0.256 mA/cm-2 and 0.216, respectively. • The performance of the proposed PFC is superior to that of most reported PFC systems. The performance of a photocatalytic fuel cell (PFC) depends on its photoelectrode. In this work, a novel three-dimensional flower-like hierarchical photoanode Zn Zr MOF/FeWO 4 /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 FeWO 4 and Zn Zr 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 FeWO 4 , which helps to separate electron-hole pairs. The main reactive materials responsible for degrading rhodamine B are h + and ·O 2 -. This research provides a new idea for developing an efficient visible light response photoanode. [Display omitted] [ABSTRACT FROM AUTHOR]

The Co 2 -Fe 8 -BTC/g-C 3 N 4 /Bi 2 O 3 /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-C 3 N 4 /Bi 2 O 3 /Ti photoanode (0.19 mA·cm-2, 11.64 μW·cm-2, 55.37 %, respectively) and Bi 2 O 3 /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 Co 2 -Fe 8 -BTC, g-C 3 N 4 and Bi 2 O 3 , 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. [ABSTRACT FROM AUTHOR]

• A double Z-scheme heterojunction Ce-UiO-66/g-C 3 N 4 /Bi 2 WO 6 /Ti photoanode was prepared and applied to PFC. • Excellent performance of the PFC is attributed to strong redox ability of Bi 2 WO 6 and g-C 3 N 4 , and special e- transfer mode of Ce-UiO-66. • The RhB degradation rate, V oc , J sc and P max of the PFC were respectively 90.9 %, 0.37 V, 0.152 mA cm-2 and 7.53 µW cm-2. • The turnover frequency of RhB degradation by the PFC reached 0.98 h-1. • RhB was degraded by •O 2 -, h + and •OH through deethylation and ring-opening reactions. In order to enhance the carrier separation efficiency and redox ability of photoanode, a dual Z-scheme heterojunction Ce-UiO-66/g-C 3 N 4 /Bi 2 WO 6 /Ti photoanode was prepared and assembled with Cu cathode to form PFC. The characterization results show that Ce-UiO-66/g-C 3 N 4 /Bi 2 WO 6 uniformly distributed on the Ti substrate, with average crystallite size of 9.04 nm and average particle size of 33.05 nm, which provides sufficient reactive active sites for RhB degradation. The RhB degradation rate, P max , J sc , V oc and FF of the PFC were 90.9 % (90 min), 7.53 µW cm-2, 0.152 mA cm-2, 0.37 V and 0.134, respectively. The turnover frequency (TOF) for RhB degradation by the PFC reached 0.98 h-1. Fermi energy level analysis shows that a double-Z heterojunction is formed between Bi 2 WO 6 and g-C 3 N 4 , and between Bi 2 WO 6 and Ce-UiO-66, which not only effectively separates photogenerated e-- h +, but also retains the high redox ability of the composite. Moreover, with the introduction of Ce-UiO-66, the composite photoanode has larger specific surface area and wider visible light absorption range. In addition, because of the built-in electric field, the photogenerated electrons can migrate to the surface of composite particles more easily and react with dissolved oxygen to generate more •O 2 - to participate in the degradation of RhB. This work provides a valuable reference for developing PFC photoanode with high efficiency and visible light response. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The features and designed strategy of photoelectrode has been discussed comprehensively. • The diverse fields of application for SPES based on photoelectrode have been described in detail. • SPES-based on PFC, SPES-based on PEC, SPES-based on PZAB and others have been discussed to detect various target. • Comparative analysis of SPES based on photoelectrode performance and perspective has been discussed briefly. Self-powered electrochemical sensor (SPES), an analytical sensing device without external power supply, is integrated with the dual functions of power supply and detection performance. Compared with traditional electrochemical sensors, SPES has many potential advantages, such as easy miniaturization, easy portability, wireless transmission, intelligence, and energy self-supply. In the background of the booming Internet of Things and artificial intelligence, the self-powered operation of intelligent sensing equipment is an ideal choice. As a new type of electrochemical sensing device, SPES will receive extensive attention in the fields of electroanalytical chemistry, including wearable sensing devices, portable sensing devices, implantable devices, smart sensing devices, and the like. Herein, an overview of recent developments achieved in SPES based on photoelectrode, including SPES-based on photocatalytic fuel cell, SPES-based on photoelectrochemical, SPES-based on photoassisted zinc-air battery and others, is provided for the application of disease diagnosis, environmental monitoring, food safety, biomedicine. We summarized the preparation of different photoelectrode and the composition of photoelectrochemical system for sensing. The photoelectrode involved in the excellent photoelectric material are particularly emphasized and the related sensing strategies are mentioned. Finally, the challenges, future trends, and prospects associated with SPES based on photoelectrode are also discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnO/Bi 2 MoO 6 /ZIF-67 photocatalyst synthesized and immobilized on FTO. • A planar PFC microreactor for TTC removal was designed. • Tetracycline removal was matched with the Langmuir-Hinslewood kinetic model. • Under optimal conditions: P max = 1.35 mW/cm2, I sc = 4.1 mA/ cm2 was obtained. • The effects of electrolytes in the μPFC system were evaluated. In the Photocatalytic fuel cell microreactor system, a three-component photocatalyst powder of ZnO nanorod/Bi 2 MoO 6 /ZIF-67 was synthesized and deposited as a photoanode immobilize on an FTO substrate using the drop-casting method. The electrochemical properties and photocurrent obtained in the ZnO/Bi 2 MoO 6 /ZIF-67 photoanode/FTO system exceeded those of ZnO/Bi 2 MoO 6 /FTO and ZnO/FTO. The use of the ZnO/Bi 2 MoO 6 /ZIF-67 composite on the FTO substrate led to a reduction in the bandgap energy from 1.74 ev to 1.61 ev. The optimal conditions for tetracycline degradation included a tetracycline concentration of 20 ppm, a pH of 7, light intensity of 7.9 mW/cm2, and a flow rate of 120 µL/min. Under these conditions, the removal efficiency and TOC were calculated as 97.16 % and 92.4 %, respectively. The maximum power density was 35.1 mW/cm2, and the photocurrent density was 1.4 mA/cm2. The kinetics of tetracycline removal in the microreactor input followed the Langmuir-Hinshelwood model, and mass transfer resistance in the fluid phase did not significantly affect the reaction kinetics. Additionally, the time-on-stream (TOS) curve indicated that the removal efficiency dropped below 80 % after 1450 min of operation, reaching a breaking point. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel PFC system based on WO 3 and P-BiVO 4 /CQDs was constructed. • Superior P max and Cr(VI) reduction were simultaneously realized in the PFC. • V oc , J sc and P max were respectively 0.83 V, 0.42 mA·cm−2 and 0.1 mW·cm−2. • The addition of CQDs remarkably hampered the recombination of charge carriers. • The optimized PFC displayed superior stability and practicability. Developing efficient and sustainable photoelectrodes in photocatalytic fuel cell (PFC) system remains a major challenge. In this work, a PFC system (WO 3 |P-BiVO 4 /CQDs) was established based on WO 3 photoanode and P-BiVO 4 photocathode loaded with carbon quantum dots (CQDs) for Cr(VI) reduction with simultaneous electricity production. The photocatalytic performance of the constructed PFC system was characterized by various analytical methods. With the introduction of CQDs, both Cr(VI) reduction and maximum power density (P max) have been significantly enhanced. When the loading amount of CQDs was 150 μL, its Cr(VI) reduction rate and maximum power density (P max) were respectively 90 % and 0.10 mW/cm2 within 180 min of illumination, superior to the WO 3 |P-BiVO 4 system. This was attributed to the decoration of CQDs, which broadened the light absorption range, increased the isolation efficiency of charge carriers and ultimately enhanced the ability of the fabricated PFC system. The superior stability and practicability were also demonstrated by five cyclic experiments. In addition, the plausible mechanism was proposed. This work offers an important reference for the application of the PFC system in wastewater treatment. [ABSTRACT FROM AUTHOR]

Unavoidable organics in uranium wastewater or contaminated waters derive great challenges to traditional uranium removal techniques. Here, a drivingpower enhanced photocatalytic fuel cell (DEPFC) is designed by using a carbon felt (CF)-based UiO-66-NH 2 derived zirconia (ZrO 2)/N-doped porous carbon (ZrON-C/CF) cathode and a monolithic photoanode, composing of a front FTO glass-based BiVO 4 film and a rearmounted Si photovoltaic cell, for effectively oxidizing organics and simultaneously reducing UO 2 2+ from complex wastewater under sunlight illumination. The water contact angle measurements demonstrate that ZrO 2 can improve the hydrophilia of cathode thus increases the contact between UO 2 2+ and cathode. The density functional theory indicates that N-doping can enhance the electronegativity of cathode and increases UO 2 2+ adsorption. Meanwhile, the enhanced UO 2 2+ reduction facilitates the charge separation in BiVO 4 film, therefore enhancing the organic oxidation. Consequently, under AM 1.5 illumination, the designed DEPFC can remove almost 100% of UO 2 2+ and simultaneous degrade 99% organics within 40 min [Display omitted] • A novel drivingpowers enhanced photocatalytic fuel cell system was fabricated. • The introduction of photovoltaic cell provides greater drivingpowers than conventional PFC. • The incorporation of ZrO 2 can improve the hydrophilia of cathode. • N-doping can enhance the electronegativity and enrich nitrogen-containing functional group of cathode. • The DEPFC can remove almost 100% of U(VI) and simultaneous degrade more than 99% TC under 40 min illumination. [ABSTRACT FROM AUTHOR]

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 In 2 S 3 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. A dual-functional photocatalytic fuel cell (PFC) with improved solar-to-electricity energy conversion efficiency and renewable biomass sensitivity performance was developed. [Display omitted] • Novel SiNWs-based PFC to achieve the dual-function of solar-to-electricity conversion and self-powered glucose detection. • The uniform conductive PANI films on the p-SiNWs photocathode accelerate the charge transfer rate at the interface. • The S-scheme band alignments in the n-SiNWs/In 2 S 3 heterojunction improve the carrier separation and transfer efficiency. • Excellent energy conversion and effective detection performance towards glucose. [ABSTRACT FROM AUTHOR]

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/Bi 2 MoO 6 /MIL-101; ZnO/Bi 2 MoO 6 ; ZnO) and a photocathode (Cu/CuO/Cu 2 O). 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/Bi 2 MoO 6 /MIL-101, which is 7.8 and 1.8 times higher than ZnO and ZnO/Bi 2 MoO 6 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. [Display omitted] [ABSTRACT FROM AUTHOR]

The performance of photocatalytic fuel cell (PFC) is mainly determined by photoanode. In order to reduce the recombination rate of electron–hole pairs and extend the light response wavelength, g-C3N4/WO3/TiO2/Ti photoanode was successfully fabricated by mixed sol–gel dipping method. Its maximum photocurrent density is 2.27 mA·cm−2 at 1.1 V (vs. SCE), which is 1.64 and 1.57 times that of WO3/TiO2/Ti and g-C3N4/TiO2/Ti, respectively. The maximum power density, short circuit current density, and RhB degradation efficiency of PFC with g-C3N4/WO3/TiO2/Ti-Cu photoanode and Cu cathode are 19.35 μW·cm−2, 0.20 mA·cm−2, and 87.7%, respectively. The excellent performance of PFC is mainly attributed to the fact that TiO2/Ti is co-doped with g-C3N4 and WO3, which greatly expands its light absorption range, strengthen its light absorption intensity, and improves its carrier mobility. [ABSTRACT FROM AUTHOR]

Biochar has been obtained by pyrolysis of spent malt rootlets under limited oxygen supply and further activated by mixing with KOH and pyrolyzed again at high temperature. The total specific surface area of such activated biochar was 1148 m2 g−1, while that of micropores was 690 m2 g−1. This biochar was used to make a functional electrode by deposition on carbon cloth and was combined with a photoelectrochemical cell. The biochar electrode functioned as a supercapacitor in combination with the electrolyte of the cell, reaching a specific capacity of 98 Fg−1, and it was capable of storing charges generated by the cell, proving current flow both under illumination and in the dark. The same electrode could be used as an air-cathode providing oxygen reduction functionality and thus demonstrating interesting electrocatalyst properties.

The design of high efficiency photoanode is still the critical of photocatalytic fuel cell (PFC). In this study, BiOBr/Bi5O7I/TiO2/Ti photoanode was prepared for the first time whose photocurrent density was 2.33 mA cm−2 at 1.2 V (vs. SCE) under visible light irradiation, which was 2.31 times that of BiOBr/TiO2/Ti. The rhodamine B degradation rate, maximum power density, short‐circuit current density and open circuit voltage of PFC with BiOBr/Bi5O7I/TiO2/Ti photoanode were (94.75± 2.01)%, (23.49± 1.12) μW cm−2, (0.36± 0.01) mA cm−2 and 0.54 V, respectively. The excellent performance was attributed to the herterojunction of the photoanode, which expanded the photoresponse wavelength of photoanode, was beneficial to charge transfer, and enhanced the separation efficiency of photogenerated electrons and holes. [ABSTRACT FROM AUTHOR]

The practical application of a photocatalytic fuel cell (PFC) is usually limited by its long pollutant degradation period. Here, two strategies were adopted to improve the PFC performance. On one hand, a ternary Z-scheme heterojunction photocatalyst (Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds) was used as the photoanode to promote the separation of photo-generated charge carriers, thereby improving the photocatalytic process. On the other hand, CuFe 2 O 4 was used as the photocathode to activate persulfate (PS) to further enhance pollutant degradation and electricity generation. The results indicated that, under visible light irradiation (45 min), the degradation efficiency of tetracycline by the coupling system of Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds-CuFe 2 O 4 + PS (PFCps) reached to 94.5%. The corresponding first-order kinetic constant was 8.13, 3.40, 3.34, and 1.89 times that of PS, Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds + PS, CuFe 2 O 4 + PS, and Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds-CuFe 2 O 4 , respectively. The highest maximum power density of the PFCps system was 37.0 μW·cm−2, which was 1.89 times that of the PFC of Bi 2 O 4 /Bi 2 WO 6 /C 3 N 4 qds-CuFe 2 O 4. The reactive species capturing experiments verified that ·OH, ·O 2 -, h +, and ·SO 4 - had positive effects on the tetracycline degradation. In addition, the mechanism involved in the PFCps system was proposed. This work provided a novel idea for the development of coupling technologies to treat antibiotic wastewater. [Display omitted] • A ternary Z-scheme heterojunction was prepared by combining Bi 2 O 4 , Bi 2 WO 6 and C 3 N 4 qds • The Z-scheme photocatalyst promoted electron transfer from photoanode to photocathode • PS activation was facilitated in this Z-scheme PFC with CuFe 2 O 4 as photocathode • PFC+PS system simultaneously enhanced TC degradation and electricity generation • ·OH, ·O 2 -, h +, and ·SO 4 - had positive effects on TC degradation in the PFC+PS system [ABSTRACT FROM AUTHOR]

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 C 3 N 5 /TNAs photoanode assisted by Fenton-like reaction (C 3 N 5 /TNAs-PFC-Fenton) system was built for p -Chloronitrobenzene degradation and electricity production. The working function confirmed the band bending of C 3 N 5 and TNAs, and density functional theory calculations indicated the formation of internal electric field at heterojunction interface of C 3 N 5 and TNAs, which promoted visible-light absorption capacity and charge transfer property of C 3 N 5 /TNAs photoanode. The incorporation of Fenton-like reaction into C 3 N 5 /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, •O 2 − and 1O 2 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 C 3 N 5 /TNAs-PFC-Fenton system. The C 3 N 5 /TNAs-PFC-Fenton system exhibited fine universality for degradation of organic pollutants and electricity production. • The C 3 N 5 modified TNAs photoanode with internal electric field was prepared. • PFC assisted by Fenton-like reaction with C 3 N 5 /TNAs photoanode was constructed. • C 3 N 5 /TNAs-PFC-Fenton system promoted p -CNB degradation and electricity generation. • The S-scheme charge transfer mechanisms of C 3 N 5 /TNAs was proved. • Degradation pathways and overall toxicity variation of p -CNB were proposed. [ABSTRACT FROM AUTHOR]

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 CuBi 2 O 4 /Bi 2 WO 6 /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. [Display omitted] • CuBi2O4/Bi2WO6/ZnO NRA photoanode was devised and applied in a sunlight-powered PFC. • Integrating CuBi2O4 and Bi2WO6 boosted the optical and electrochemical traits of ZnO NRA. • Municipal wastewater was treated and electrical power was yielded concurrently in the cell. • Enhancement was due to the synergy effect of 1-D ZnO NRA morphology and dual S-scheme heterostructure. • Phototoxicity data testified that the treated wastewater has no harmful effect on Vigna radiata. [ABSTRACT FROM AUTHOR]

[Display omitted] • New photoactive mesoporous Ce-modified TiO 2 with improved oxide layer resistance. • High photocatalytic activity towards phenol degradation. • Efficient anode materials for photo electrochemical system. In the present paper is presented an efficient strategy for synthesis of mesoporous TiO 2 modified with different Ce concentrations through a sol–gel process in the presence of triblock Pluronic P123 as structure directing agent, integrated with evaporation-induced self- assembly (EISA) approach. The nanocomposite consisted mostly of small crystallite of anatase. The presence of a new crystal phase corresponding to cerium titanate was evidenced in Ce-modified powder samples. All materials were characterized by SEM and TEM microscopies, UV–vis, XPS and N 2 adsorption-desorption isotherms in order to examine the textural and structural characteristics and the chemical nature of their surface. Furthermore, the photoelectrochemical characterization evidenced the effect of the TiO 2 mesoporous structure, the amount of cerium and the oxidation state of Ti and Ce in the new photocatalysts on the enhanced photovoltaic performance. The photocatalytic activity of the as-synthesized materials was evaluated for phenol photodegradation in aqueous media and the reactive species involved in photocatalytic process were established by using some radical scavengers in the photodegradation experiments. Based on the obtained results, these new Ce-modified mesoporous TiO 2 photocatalysts could be considered for degradation of organic compounds from wastewaters by advanced oxidation processes or for photoanodes construction for efficient photoelectrochemical fuel cell (PFC) systems. [ABSTRACT FROM AUTHOR]

The photocatalytic fuel cell (PFC) synergistically utilizes the photocatalytic oxidation of biomass and the electrochemical reaction of the fuel cell to selectively reduce oxygen to produce hydrogen peroxide (H2O2) at room temperature. Herein, we report a PEC system that NiFe-layered double oxide (LDO)/TiO2 as photoanode, carbon black as cathode for utilizing biomass and oxygen to simultaneously convert solar energy into electricity and produce hydrogen peroxide without applied electric bias. The photoanode catalyst was fabricated with TiO2-supported NiFe mixed metal oxides (MMO) which obtained by layered double hydroxides (LDHs) pyrolysis. The research results indicate that under solar irradiation, the photocurrent density and faraday efficiency have a significantly improved compared with pure NiO/TiO2. With methanol as the feeding fuel at the photoanode, the optimal device yields an excellent open circuit voltage (Voc), short circuit current (Jsc) and a maximum power density (Pmax) of 0.78 V, 1093 μA/cm² and 169 μW/cm², respectively. This performance improvement is attributed to the Fe3+ doped in NiFe-MMO and use TiO2 as an electron transport layer. Simultaneously, the hydrogen peroxide concentration reached 0.443 mM after 180 min illumination at the cathode, the generation rate was optimized to 0.126 μmol/min/cm² at neutral aqueous solution. The PEC system exhibited an excellent higher rate of production for H2O2, and faraday efficiency (FE) reached 31.7 %. This PFC is a green technology for photocatalytically oxidize biomass at the photoanode and convert solar energy into electricity as well as supply it to the cathode to reduce O2 to produce H2O2 efficiently. [ABSTRACT FROM AUTHOR]

Biochar has been made by carbonization of spent coffee grounds without further activation and has been characterized by several techniques revealing a material with a satisfactory balance of microporosity with meso and macroporosity. The material was fairly pure with 96% of its mass made of carbon and oxygen, 2.2% of K and the rest of unidentified minerals. This biochar was used to make a supercapacitor electrode combined with a photocatalytic fuel cell as an electric power source. It has been shown that the present biochar does apply as material to make a supercapacitor with specific capacitance mounting up to 200 Fg−1. Its combination with a photocatalytic fuel cell can be designed into a very simple system which provides several functions in one single device: solar energy conversion, photocatalytic degradation of an organic substance and storing of electric energy in a supercapacitor.

Technological advancement is accompanied by excessive consumption of fossil fuels and affluent uses of chemical substances in many sectors, including transportation and manufacturing companies, and so on. Being an exhaustible resource, the excessive use of fossil fuels and of chemical substances may lead to a serious energy crisis in the long run, and it may additionally impose environmental pollution. Attempts have been made in the solution of such serious issues from every nook and corner. Nonetheless, no method has been found to be a panacea in waste water treatment and subsequent beneficiaries. One of the attempts in the solution to such issues is the application of photocatalytic technology, which could serve as a dual function in environmental remediation and clean energy production. A photocatalytic fuel cell is a tool developed for the recovery of energy from organic wastes. A rational cell construction needs the fabrication of photoelectrodes, the design of a photoanode and a photocathode chamber, in addition to an ion-transport membrane for pollution treatment and electricity generation. In this review, comprehensive fundamental assessments and recent developments in the design of photocatalytic fuel cells, their applications, future prospects, and challenges are covered.