Advancing BiVO4 Photoanode Activity for Ethylene Glycol Oxidation via Strategic pH Control.

The photoelectrochemical (PEC) conversion of organic small molecules offers a dual benefit of synthesizing value-added chemicals and concurrently producing hydrogen (H2). Ethylene glycol, with its dual hydroxyl groups, stands out as a versatile organic substrate capable of yielding various C1 and C2 chemicals. In this study, we demonstrate that pH modulation markedly enhances the photocurrent of BiVO4 photoanodes, thus facilitating the efficient oxidation of ethylene glycol while simultaneously generating H2. Our findings reveal that in a pH = 1 ethylene glycol solution, the photocurrent density at 1.23 V vs. RHE can attain an impressive 7.1 mA cm-2, significantly surpassing the outputs in neutral and highly alkaline environments. The increase in photocurrent is attributed to the augmented adsorption of ethylene glycol on BiVO4 under acidic conditions, which in turn elevates the activity of the oxidation reaction, culminating in the maximal production of formic acid. This investigation sheds light on the pivotal role of electrolyte pH in the PEC oxidation process and underscores the potential of the PEC strategy for biomass valorization into value-added products alongside H2 fuel generation.

Recent Developments in Nickel-Based Layered Double Hydroxides for Photo(-/)electrocatalytic Water Oxidation.

Layered double hydroxides (LDHs), especially those containing nickel (Ni), are increasingly recognized for their potential in photo(-/)electrocatalytic water oxidation due to the abundant availability of Ni, their corrosion resistance, and their minimal toxicity. This review provides a comprehensive examination of Ni-based LDHs in electrocatalytic (EC), photocatalytic (PC), and photoelectrocatalytic (PEC) water oxidation processes. The review delves into the operational principles, highlighting similarities and distinctions as well as the benefits and limitations associated with each method of water oxidation. It includes a detailed discussion on the synthesis of monolayer, ultrathin, and bulk Ni-based LDHs, focusing on the merits and drawbacks inherent to each synthesis approach. Regarding the EC oxygen evolution reaction (OER), strategies to improve catalytic performance and insights into the structural evolution of Ni-based LDHs during the electrocatalytic process are summarized. Furthermore, the review extensively covers the advancements in Ni-based LDHs for PEC OER, including an analysis of semiconductors paired with Ni-based LDHs to form photoanodes, with a focus on their enhanced activity, stability, and underlying mechanisms facilitated by LDHs. The review concludes by addressing the challenges and prospects in the development of innovative Ni-based LDH catalysts for practical applications. The comprehensive insights provided in this paper will not only stimulate further research but also engage the scientific community, thus driving the field of photo(-/)electrocatalytic water oxidation forward.

Treatment of diluted palm oil mill effluent (POME) synchronous with electricity production in a persulfate oxidant-promoted photocatalytic fuel cell.

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.

Enzyme-catalyzed high-performing reaction with in-situ amplified photocurrent on carbon-functionalized inorganic photoanode for immunosensing.

An enzyme-catalyzed high-performing reaction with in-situ amplified photocurrent was innovatively designed for the quantitative screening of carcinoembryonic antigen (CEA) in biological fluids by coupling with carbon-functionalized inorganic photoanode. A split-type photoelectrochemical (PEC) immunoassay was initially executed with horseradish peroxidase (HRP)-labeled secondary antibody on the capture antibody-coated microtiter. Then, the photocurrent of carbon-functionalized inorganic photoanode were improved through enzymatic insoluble product. Experimental results revealed that introduction of the outer carbon layer on the inorganic photoactive materials caused the amplifying photocurrent because of the improving light harvesting and separation of photo-generated e-/h+ pairs. Under optimum conditions, the split-type photoelectrochemical immunosensing platform displayed good photocurrent responses within the dynamic range of 0.01 - 80 ng mL-1 CEA, and allowed the detection of CEA as low as a concentration of 3.6 pg mL-1 at the 3Sblank level. The strong attachment of antibodies onto nano label and high-performing photoanode resulted in a good repeatability and intermediate precision down to 9.83%. No significant differences at the 0.05 significance level were encountered in the analysis of six human serum specimens between the developed PEC immunoassay and the commercially available CEA ELISA kits.

Gas diffusion TiO2 photoanode for photocatalytic fuel cell towards simultaneous VOCs degradation and electricity generation.

In this work, a photocatalytic fuel cell (PFC) with a gas diffusion TiO2 photoanode is proposed to directly convert chemical energy contained in volatile organic compounds into electricity by using solar energy. The gas diffusion TiO2 photoanode is prepared by coating TiO2 nanoparticles onto Ti mesh, whose intrinsic porous structure allows for gaseous pollutants to directly transfer inside the photoanode and thereby enhances mass transport. The feasibility of the developed gas diffusion photoanode is demonstrated by degrading toluene as a model gaseous pollutant. It is shown that the newly-developed PFC yields better electricity generation and toluene removal efficiency due to the enhanced mass transport of toluene and the eliminated interference of gas bubbles. The short-circuit current density and maximum power density of the PFC with a gas diffusion TiO2 photoanode (0.1 mA/cm2 and 0.02 mW/cm2) are about 3.3 times and 4 times as those of the bubbling PFC (0.03 mA/cm2 and 0.005 mW/cm2), respectively. Both the discharging performance and toluene removal efficiency increase with increasing the light intensity and electrolyte concentration, while there exists an optimal gas flow rate leading to the best performance. The present work provides an innovative strategy for clean processing of volatile organic compounds while recycling the contained chemical energy.

Enhanced photoelectrocatalytic decomplexation of Ni-EDTA and simultaneous recovery of metallic nickel via TiO2/Ni-Sb-SnO2 bifunctional photoanode and activated carbon fiber cathode.

In order to enhance Ni-EDTA decomplexation and Ni recovery via photoelectrocatalytic (PEC) process, TiO2/Ni-Sb-SnO2 bifunctional electrode was fabricated as the photoanode and activated carbon fiber (ACF) was introduced as the cathode. At a cell voltage of 3.5 V and initial solution pH of 6.3, the TiO2/Ni-Sb-SnO2 bifunctional photoanode exhibited a synergetic effect on the decomplexation of Ni-EDTA with the pseudo-first-order rate constant of 0.01068 min-1 with 180 min by using stainless steel (SS) cathode, which was 1.5 and 2.4 times higher than that of TiO2 photoanode and Ni-Sb-SnO2 anode, respectively. Moreover, both the efficiencies of Ni-EDTA decomplexation and Ni recovery were improved to 98% from 86% and 73% from 41% after replacing SS cathode with ACF cathode, respectively. Influencing factors on Ni-EDTA decomplexation and Ni recovery were investigated and the efficiencies were favored at acidic condition, higher cell voltage and lower initial Ni-EDTA concentration. Ni-EDTA was mainly decomposed via ·OH radicals which generated via the interaction of O3, H2O2, and UV irradiation in the contrasted PEC system. Then, the liberated Ni2+ ions which liberated from Ni-EDTA decomplexation were eventually reduced to metallic Ni on the ACF cathode surface. Finally, the stability of the constructed PEC system on Ni-EDTA decomplexation and Ni recovery was exhibited.

Revealing the Essential Role of Iron Phosphide and its Surface-Evolved Species in the Photoelectrochemical Water Oxidation by Gd-Doped Hematite Photoanode.

Phosphates are easily derived from transition metal phosphides under natural conditions, and the real roles of these two in catalytic reactions are not yet clear. Here, a multiphase FeP/Gd-Fe2 O3 shell-core structure photoanode was constructed and explored regarding the real role of FeP and its surface-reconstructed iron phosphate (Fe-Pi) in photoelectrochemical water oxidation. The FeP/Gd-Fe2 O3 photoanode exhibited an excellent photocurrent density of 2.56 mA cm-2 at 1.23 V versus the reversible hydrogen electrode, up to 4 times greater than those of the pristine α-Fe2 O3 (0.64 mA cm-2 ). Detailed studies showed that FeP could act as a photosensitizer to enhance light absorption and as a conductive layer to accelerate charge transfer. The FeP significantly enhanced the incident photon-to-current conversion efficiency of the photoanode and improved the electron transition within the photoanode. Naturally evolved Fe-Pi on the surface provided more active sites for water oxidation. They effectively passivated the surface capture state and synergistically inhibited the electron-hole recombination. Moreover, the in-situ constructed multiphase catalyst had a smaller interfacial contact resistance than the intentionally decorative cocatalyst. This work provides new insight into the understanding of the essential role of transition metal phosphides and their surface-reconstructed species in catalytic reactions.

Self-powered photoelectrochemical biosensor with inherent potential for charge carriers drive.

Self-powered photoelectrochemical (PEC) sensing platform without external voltage has provided a breakthrough in the development of biosensors, however, it is necessary to find suitable Fermi energy level difference between photoanode materials and photocathode materials as the driving force. Herein, the self-powered PEC sensor was developed to combine the advantages of both the photoanode (SnS2/In2S3) and the photocathode (CuInS2). The sufficient Fermi level differentiation between the photoanode with the photocathode not only resulted in an evident photocurrent response vis tuning the electron transfer but avoided redox reactions of extra electron donors/acceptors to enhance the accuracy of the sensor. The biological target was immobilized on the photocathode, which allowed the sensor to possess a good anti-interference capability for the detection of real samples. The proposed PEC sensor exhibits good sensitivity for the cytokeratin 19 fragment (CYFRA21-1) detection and a low limit of detection (LOD) of 6.57 fg mL-1. Moreover, the as-purposed PEC system with good anti-interference capability and accuracy has implications for the detection of other biomarkers.

Covalent Grafting of Ruthenium Complexes on Iron Oxide Nanoparticles: Hybrid Materials for Photocatalytic Water Oxidation.

The present environmental crisis prompts the search for renewable energy sources such as solar-driven production of hydrogen from water. Herein, we report an efficient hybrid photocatalyst for water oxidation, consisting of a ruthenium polypyridyl complex covalently grafted on core/shell Fe@FeOx nanoparticles via a phosphonic acid group. The photoelectrochemical measurements were performed under 1 sun illumination in 1 M KOH. The photocurrent density of this hybrid photoanode reached 20 µA/cm2 (applied potential of +1.0 V vs reversible hydrogen electrode), corresponding to a turnover frequency of 0.02 s-1. This performance represents a 9-fold enhancement of that achieved with a mixture of Fe@FeOx nanoparticles and a linker-free ruthenium polypyridyl photosensitizer. This increase in performance could be attributed to a more efficient electron transfer between the ruthenium photosensitizer and the Fe@FeOx catalyst as a consequence of the covalent link between these two species through the phosphonate pendant group.

Single-Atom-Based Heterojunction Coupling with Ion-Exchange Reaction for Sensitive Photoelectrochemical Immunoassay.

Benefiting from the maximum atom-utilization efficiency and distinct structural features, single-atom catalysts open a new avenue for the design of more functional catalysts, whereas their bioapplications are still in their infancy. Due to the advantages, platinum single atoms supported by cadmium sulfide nanorods (Pt SAs-CdS) are synthesized to build an ultrasensitive photoelectrochemical (PEC) biosensing platform. With the decoration of Pt SAs, the PEC signal of CdS is significantly boosted. Furthermore, theory calculations indicate the positively charged Pt SAs could change the charge distribution and increase the excited carrier density of CdS. Meanwhile, it also suggests that Cu2+ can severely hinder the photoexcitation and electron-hole separation of CdS. As a proof of concept, prostate-specific antigen is chosen as the target analyte to demonstrate the superiority of the Pt SAs-CdS-based PEC sensing system. As a result, the PEC biosensor based on Pt SAs-CdS exhibits outstanding detection sensitivity and promising applicability.

Photoelectrocatalytic reactor improvement towards oil-in-water emulsion degradation.

Oil-in-water (O/W) emulsion is critical wastewater that is challenging to eliminate and requires a long treatment process, and it is necessary to develop highly effective removal methods before releasing it into natural water sources. This research has selected the photoelectrocatalytic (PEC) technique to solve this problem by developing a PEC reactor for high efficiency in O/W degradation and understanding the essential factors related to the PEC reactor's efficiency improvement. The PEC reactor has been designed on a large scale with suitable positioning of an electrode that is, designing a light source near the anode electrode to enhance light irradiation efficiency and including a circulating pump to provide continuous flow to the solution through the electrode surface. We studied the main factors of supporting the electrolyte, electrode characteristics, and catalytic process. We investigated the O/W-degradation efficiency using a UV/Vis spectrophotometer, chemical oxygen demand (COD) measurement, and GC-MS analysis. We optimized the PEC reactor using the developed BiVO4 photoanodes and placed them parallel with the zinc plates. Then, we controlled the applied potential at 1.0 V in 0.1 M Na2SO4 supporting an electrolyte under visible light irradiation. The developed PEC reactor can be degraded in the O/W emulsion up to 76% and decreased the COD value up to 78% for 7h. This PEC cell can be completely decomposed of many functional groups, such as carbonyl, ester, nitrile, amine, phosphate, chloro group, and nitro group, that were contained in the O/W substance. The highlight of this research is the designed light source and circulating pump inside of the PEC reactor to enhance the light irradiation, refresh the anode electrode, and understand the critical factor for the improvement of O/W-degradation efficiency. This PEC reactor presents a high-efficiency O/W degradation with practical use and a fast process suitable for further application in high turbidity of wastewater treatment from the oil industry.

A self-powered photoanode-supported photoelectrochemical immunosensor for CYFRA 21-1 detection based on In2O3/In2S3/CdIn2S4 heterojunction.

A self-powered photoanode-supported photoelectrochemical (PEC) immunosensor was designed based on In2O3/In2S3/CdIn2S4 as photoanode and PDA@CNTs as biocathode for the detection of CYFRA 21-1. In this proposal, In2O3/In2S3/CdIn2S4 heterojunction modified indium-tin oxide (ITO) electrode was served as a substitute for platinum (Pt) counter electrode to provide an evident and stable photocurrent signal. The matched band structure of In2O3, In2S3 and CdIn2S4 as well as the unique hollow porous structure of In2O3/In2S3/CdIn2S4 played a pivotal role in accelerating the separation and transfer of photocarrier. Meanwhile, PDA@CNTs with excellent conductivity further enhanced the photocurrent which was provided by photoanode In2O3/In2S3/CdIn2S4 heterojunction. Besides, PDA could effectively capture the antibody (Ab) through Michael addition. Separating photoanode from the sensing biocathode was conducive to improve the anti-interference capability of PEC sensor because the reductive species in biologic media will change PEC properties of the photoanode interface. Under optimal conditions, the PEC immunosensor have realized the detection of CYFRA 21-1 (0.5 pg/mL - 50 ng/mL) and the detection limitation with 0.16 pg/mL. In addition, the proposed self-powered PEC sensor with acceptable selectivity, reproducibility, and stability provide a new horizon for designing PEC immunosensing platform in bioassays.

A self-powered photoelectrochemical cathodic aptasensor for the detection of 17ß-estradiol based on FeOOH/In2S3 photoanode.

In this work, a novel self-powered photoelectrochemical (PEC) aptasensor integrated photoanode and photocathode for the accurate and selective detection of 17ß-estradiol (E2) was proposed for the first time. FeOOH/In2S3 heterojunction was built initially and used as a substitute for platinum (Pt) counter electrode. The matched band gap edge of FeOOH and In2S3 facilitated the transfer of photo-generate electrons to photoanode, while the holes left in the valence band of photocathode (CuInS2) can be attracted by the electrons flowed from the photoanode, which reduced the recombination of electron-hole pairs and promote the cathodic photocurrent. Under optimal conditions, the constructed cathodic aptasensor of E2 presented linear scope in 10 fg/mL-1 µg/mL with detection limit of 3.65 fg/mL. Besides, the cathodic aptasensor exhibited admiring selectivity, stability and reproducibility. This work verified that the cathodic photocurrent response can be regulated by the corresponding photoanode which provided a new design thought for PEC aptasensor on the basis of p-type semiconductor.

Rational Design Combining Morphology and Charge-Dynamic for Hematite/Nickel-Iron Oxide Thin-Layer Photoanodes: Insights into the Role of the Absorber/Catalyst Junction.

Water oxidation represents the anodic reaction in most of the photoelectrosynthetic setups for artificial photosynthesis developed so far. The efficiency of the overall process strongly depends on the joint exploitation of good absorber domains and interfaces with minimized recombination pathways. To this end, we report on the effective coupling of thin-layer hematite with amorphous porous nickel-iron oxide catalysts prepared via pulsed laser deposition. The rational design of such composite photoelectrodes leads to the formation of a functional adaptive junction, with enhanced photoanodic properties with respect to bare hematite. Electrochemical impedance spectroscopy has contributed to shed light on the mechanisms of photocurrent generation, confirming the reduction of recombination pathways as the main contributor to the improved performances of the functionalized photoelectrodes. Our results highlight the importance of the amorphous catalysts' morphology, as dense and electrolyte impermeable layers hinder the pivotal charge compensation processes at the interface. The direct comparison with all-iron and all-nickel catalytic counterparts further confirms that control over the kinetics of both hole transfer and charge recombination, enabled by the adaptive junction, is key for the optimal operation of this kind of semiconductor/catalyst interfaces.

Photoelectrochemical cell enhanced by ternary heterostructured photoanode: Toward high-performance self-powered cathodic cytosensing.

Previously reported photoelectrochemical (PEC) cytosensing commonly relied on the use of photoelectrodes as both signaling sources and platforms to accommodate the biorecognition events. In such a design, the side reaction between photoelectrodes and potential reductive species in the biological media as well as the interplay between the photoelectrodes and biomolecules will inevitably impair the performance of the corresponding PEC cytosensors. Herein, we presented a facile and efficient PEC cytosensor by separating capture probe from the photoelectrode. The system is operated upon by using a ternary heterostructured photoanode to provide an evident and stable photocurrent signal, an aptamer-based biocathode for recognizing and capturing the target cells, and the corresponding signal reduction from the cell-induced steric hindrance effect. Exemplified by human breast cancer cells (MCF-7), the proposed system realizes the separation of the signaling photoanode and the sensing biocathode toward a sensitive and selective self-powered PEC MCF-7 cytosensor. This work reports a new PEC cytosensing protocol, and it is expected to attract more interest in the research of high-performance PEC cytosensing.

Stable Molecular Surface Modification of Nanostructured, Mesoporous Metal Oxide Photoanodes by Silane and Click Chemistry.

Binding functional molecules to nanostructured mesoporous metal oxide surfaces provides a way to derivatize metal oxide semiconductors for applications in dye-sensitized photoelectrosynthesis cells (DSPECs). The commonly used anchoring groups, phosphonates and carboxylates, are unstable as surface links to oxide surfaces at neutral and high pH, leading to rapid desorption of appended molecules. A synthetically versatile molecular attachment strategy based on initial surface modification with a silyl azide followed by click chemistry is described here. It has been used for the stable installation of surface-bound metal complexes. The resulting surfaces are highly stabilized toward complex loss with excellent thermal, photochemical, and electrochemical stabilities. The procedure involves binding 3-azidopropyltrimethoxysilane (APTMS) to nanostructured mesoporous TiO2 or tin-doped indium oxide (ITO) electrodes by silane attachment followed by azide-terminated, Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions with an alkyne-derivatized ruthenium(II) polypyridyl complex. The chromophore-modified electrodes display enhanced photochemical and electrochemical stabilities compared to phosphonate surface binding with extended photoelectrochemical oxidation of hydroquinone for more than ∼6 h with no significant decay.

Photoelectrochemical Gas-Electrolyte-Solid Phase Boundary for Hydrogen Production From Water Vapor.

Hydrogen production from humidity in the ambient air reduces the maintenance costs for sustainable solar-driven water splitting. We report a gas-diffusion porous photoelectrode consisting of tungsten trioxide (WO3) nanoparticles coated with a proton-conducting polymer electrolyte thin film for visible-light-driven photoelectrochemical water vapor splitting. The gas-electrolyte-solid triple phase boundary enhanced not only the incident photon-to-current conversion efficiency (IPCE) of the WO3 photoanode but also the Faraday efficiency (FE) of oxygen evolution in the gas-phase water oxidation process. The IPCE was 7.5% at an applied voltage of 1.2 V under 453 nm blue light irradiation. The FE of hydrogen evolution in the proton exchange membrane photoelectrochemical cell was close to 100%, and the produced hydrogen was separated from the photoanode reaction by the membrane. A comparison of the gas-phase photoelectrochemical reaction with that in liquid-phase aqueous media confirmed the importance of the triple phase boundary for realizing water vapor splitting.

Modular Construction of Photoanodes with Covalently Bonded Ru- and Ir-Polypyridyl Visible Light Chromophores.

1,10-phenanthroline is grafted to indium tin oxide (ITO) and titanium dioxide nanoparticle (TiO2) semiconductors by electroreduction of 5-diazo-1,10-phenanthroline in 0.1 M H2SO4. The lower and upper potential limits (-0.20 and 0.15 VSCE, respectively) were set to avoid reduction and oxidation of the 1,10-phenanthroline (phen) covalently grafted at C5 to the semiconductor. The resulting semiconductor-phen ligand (ITO-phen or TiO2-phen) was air stable, and was bonded to Ru- or Ir- by reaction with cis-[Ru(bpy)2(CH3CN)2]2+ (bpy = 2,2'-bipyridine) or cis-[Ir(ppy)2(CH3CN)2]+ (ppy = ortho-Cphenyl metalated 2-phenylpyridine) in CH2Cl2 and THF solvent at 50 °C. Cyclic voltammetry, X-ray photoelectron spectroscopy, solid-state UV-vis, and inductively coupled plasma-mass spectrometry all confirmed that the chromophores SC-[(phen)Ru(bpy)2]2+ and SC-[(phen)Ir(ppy)2]+ (SC = ITO or TiO2) formed in near quantitative yields by these reactions. The resulting photoanodes were active and relatively stable to photoelectrochemical oxidation of hydroquinone and triethylamine under neutral and basic conditions.

Zinc-aluminum oxide solid solution nanosheets obtained by pyrolysis of layered double hydroxide as the photoanodes for dye-sensitized solar cells.

Due to the superiority of metal-doped ZnO compared to TiO2, the Zn-M (M = Al3+, Ga3+, Cr3+, Ti4+, Ce4+) mixed metal oxide solid solutions have been extensively studied for photocatalytic and photovoltaic applications. In this work, a systematic research has proceeded for the preparation of a zinc-aluminum oxide semiconductor as a photoanode for the dye-sensitized solar cells (DSSCs) by a simple pyrolysis route with the Zn-Al layered double hydroxide (LDH) as a precursor. The Zn-Al oxide solid solution has been applied for DSSCs as an electron acceptor, which is used to study the influence of different Al content and sintering temperature on the device efficiency. Finally, the Zn-Al oxide solid solution with calcination temperature 600 °C and Al 27 at.% content exhibits the best performance. The photoelectric efficiency improved 100 times when the Al3+ content decreased from 44 to 27 at.%. The ZnxAlyO solid solution show a reasonable efficiency as photoanode materials in DSSCs, with the best preliminary performance reported so far, and shows its potential application for the photovoltaic devices.

A novel photoactive and three-dimensional stainless steel anode dramatically enhances the current density of bioelectrochemical systems.

This study reports a high-performance 3D stainless-steel photoanode (3D SS photoanode) for bioelectrochemical systems (BESs). The 3D SS photoanode consists of 3D carbon-coated SS felt bioactive side and a flat α-Fe2O3-coated SS plate photoactive side. Without light illumination, the electrode reached a current density of 26.2 ±â€¯1.9 A m-2, which was already one of the highest current densities reported thus far. Under illumination, the current density of the electrode was further increased to 46.5 ±â€¯2.9 A m-2. The mechanism of the photo-enhanced current production can be attributed to the reduced charge-transfer resistance between electrode surface and the biofilm with illumination. It was also found that long-term light illumination can enhance the biofilm formation on the 3D SS photoanode. These findings demonstrate that using the synergistic effect of photocatalysis and microbial electrocatalysis is an efficient way to boost the current production of the existing high-performance 3D anodes for BESs.