Photoelectrochemical Materials Research Articles

Ultrathin metal–organic framework synergizes with carbon quantum dots improving photoelectrochemical water oxidation and tetracycline hydrochloride degradation performance

Finding clean dual functional materials which can simultaneously alleviate energy and environmental issues is currently a research hotspot. In our work, TiO2/CQDs/NH2-MIL-125 photoanode system was constructed to explore the application of metal–organic frameworks (MOFs) materials in water splitting and biomedical wastewater treatment. The photocurrent density of the optimal TiO2/CQDs/NH2-MIL-125 photoanode reaches 1.7 mA/cm2 at 1.23 V vs. RHE, which is about 1.8 times that of pristine TiO2. More importantly, optimized photoanode displays an excellent remove ratio toward tetracycline hydrochloride of 74 % within 60 min. Through mechanism exploration, the excellent performance is attributed to the narrow band gap of NH2-MIL-125 widens the light absorption range to the visible region. Additionally, the specific electron conduction behavior of CQDs and the type Ⅱ heterojunction between TiO2/NH2-MIL-125 inhibited the photogenerated electron-hole recombination. This work explores the application of photoelectrochemical (PEC) materials in environmental catalytic clean production.

Highly efficient Z-scheme CeO2/Bi2MoO6 heterojunction strengthened by redox mediator for photoelectrochemical detection of tetracycline with enhanced sensitivity

Accurate monitoring of antibiotics that pose risks to the environment and human health is essential. The photoelectrochemical system has emerged as a rapid and precise method for detecting environmental pollutants. However, current photoelectrochemical materials made of semiconductors face challenges due to poor photoelectric conversion efficiency. In this study, a Z-scheme CeO2/Bi2MoO6 heterojunction structure was successfully prepared by a cost-effective hydrothermal method. By leveraging built-in electric field and the Ce3+/Ce4+ redox mediator, this heterojunction achieved high photoelectrochemical conversion efficiency and functioned effectively as a sensor for tetracycline (TCH). The designed sensor demonstrated two linear ranges of 0.05–100 nM and 100–300 nM with an ultra-low detection limit of 15.4 pM for TCH. Additionally, the sensor exhibited excellent selectivity and high stability, demonstrating its potential for TCH detection in tap-water and milk samples. This study presents a simple and reliable method for the practical detection of antibiotic residues in environmental and food samples.

Cu-doped Bi2S3 nanorod films via chemical synthesis for improved photoelectrochemical water splitting

Bismuth sulfide (Bi2S3) is a promising photoelectrochemical (PEC) material due to its favorable optoelectronic properties. However, its overall PEC performance is limited by slow charge transport and high electron–hole recombination at the Bi2S3-electrolyte interface. In this study, we have intentionally introduced Cu into Bi2S3 photoelectrodes to enhance both their physical properties and PEC performance. Cu-doping concentrations ranging from 0 to 8.4 at.% were incorporated into Bi2S3 films synthesized via chemical bath deposition followed by annealing. The undoped Bi2S3 photoelectrodes exhibited nanorods with lengths of 50–100 nm, a direct bandgap of 1.26 eV, and a photocurrent density of 4.7 mA/cm2 at 1.5 V vs Hg/HgO. As the Cu-doping concentration increased from 1.0 to 4.4 at.%, the nanorod length extended to 200–400 nm, with a corresponding increase in density, leading to an enhanced photocurrent density of 6.8 mA/cm2. However, further increasing the Cu-doping concentration to 8.4 at.% resulted in a reduction in film thickness, nanorod density, and a decrease in photocurrent to 6.0 mA/cm2. These results demonstrate that Cu-doping in Bi2S3 significantly increases nanorod density and improves both the physical and PEC properties, offering a promising approach for developing more efficient PEC water-splitting devices.

Novel self-powered anti-interference photoelectrochemical sensor via zirconium porphyrin-based metal–organic framework as multifunctional signal label for oxytetracycline detection in food and environment

As a newly developed sensing mode, self-powered PEC sensing may successfully address issues like individual photoanode or photocathode sensing with poor signal responsiveness and weak anti-interference capacity. Herein, a self-powered PEC sensor was developed to detect oxytetracycline (OTC) by integrating SnS2/Sb2S3 photoanode with Cu2O photocathode, and zirconium porphyrin-based metal–organic framework (ZPM) as multifunctional signal label to achieve signal amplification. The highly efficient and stable self-powered biosensor not only delivers a sustained and robust photocurrent response for bioanalysis, thanks to its well-designed stepped band structure, but also successfully mitigates interference from reducing agents. Furthermore, the ZPM was firstly used as a multifunctional nano label in PEC biosensing platform. On the one hand, the ZPM has a large specific surface area and abundant functional groups that can be used to immobilize the aptamer. On the other hand, because of steric hindrance, poor conductivity, competition for dissolved oxygen and light source with the substrate, the ZPM can as photocathode quenching source to affect the photocurrent response. In optimized experimental conditions, the fabricated PEC sensing platform showed a broad linear range of 0.1 pM to 100 nM for assay of OTC with a low limit of detection (LOD=0.03 pM), coupled by its quantification in human serum samples with acceptable results. This work provides an avenue for the development of high-performance photoelectrochemical materials and opens up the possibility of designing more sensitive self-powered PEC biosensors.

Photoelectrocatalytic Hydrogen Generation: Current Advances in Materials and Operando Characterization.

Photoelectrochemical (PEC) hydrogen generation is a promising technology for green hydrogen production yet faces difficulties in achieving stability and efficiency. The scientific community is pushing toward the development of new electrode materials and a better understanding of the underlying reactions and degradation mechanisms. Advances in photocatalytic materials are being pursued through the development of heterojunctions, tailored crystal nanostructures, doping, and modification of solid-solid and solid-electrolyte interfaces. Operando and in situ techniques are utilized to deconvolute the charge transfer mechanisms and degradation pathways. In this review, both materials development and Operando characterization are covered for advancing PEC technologies. The recent advances made in the PEC materials are first reviewed including the applied improvement strategies for transition metal oxides, nitrites, chalcogenides, Si, and group III-V semiconductor materials. The efficiency, stability, scalability, and electrical conductivity of the aforementioned materials along with the improvement strategies are compared. Next, the Operando characterization methods and cite selected studies applied for PEC electrodes are described. Operando studies are very successful in elucidating the reaction mechanisms, degradation pathways, and charge transfer phenomena in PEC electrodes. Finally, the standing challenges and the potential opportunities are discussed by providing recommendations for designing more efficient and electrochemically stable PEC electrodes.

Absolute band-edge energies are over-emphasized in the design of photoelectrochemical materials

Absolute band-edge energies are over-emphasized in the design of photoelectrochemical materials

High-performance assaying cardiac troponin I using Bi-doped tin-based heterojunction in photoelectrochemical biosensing with the quencher of yolk-shell nanostructure

Cardiac troponin I (cTnI), a protein regulating myocardial contraction, stands the premier biomarker for diagnosing acute myocardial infarction and stratifying heart disease risk. Photoelectrochemical (PEC) biosensing combines traditional PEC analysis with high bioconjugation specificity, rendering a prospective avenue for disease biomarker analysis. However, the performance of sensors often falls short due to inadequate photoelectric materials. Hence, designing heterojunctions with proper band alignment, effective transport and separation of photogenerated carriers is highly expected for PEC sensors. Meanwhile, doping as a synergistic strategy to tune the energy band edges and improve carrier transport in heterojunctions, can also enhance the sensing performance. In this work, bismuth-doped tin oxide and tin disulfide heterojunction (Bi–SnOS) was prepared via a simple one-step hydrothermal method and utilized as a highly sensitive platform. Integrating copper sulfide-coated nano-gold (Au@CuS), a yolk-shell shaped nanocomposites, as the double quenching probe, an excellent PEC biosensor was fabricated to assay cTnI via sandwich immunorecognition. Under optimal conditions, the proposed biosensor displayed a high-performance for cTnI in the range from 0.1 pg/mL to 5.0 ng/mL with a low detection limit (44.7 fg/mL, 3σ). The strong photocurrent response, high stability and suitable selectivity point out that the synergistic effect between heterojunction and doping provides a promising prospect for the design of new PEC materials.

Molecular Photoelectrochemical Energy Storage Materials for Coupled Solar Batteries.

ConspectusSolar-to-electrochemical energy storage is one of the essential solar energy utilization pathways alongside solar-to-electricity and solar-to-chemical conversion. A coupled solar battery enables direct solar-to-electrochemical energy storage via photocoupled ion transfer using photoelectrochemical materials with light absorption/charge transfer and redox capabilities. Common photoelectrochemical materials face challenges due to insufficient solar spectrum utilization, which restricts their redox potential window and constrains energy conversion efficiency. In contrast, molecular photoelectrochemical energy storage materials are promising for their mechanism of exciton-involved redox reaction that allows for extra energy utilization from hot excitons generated by superbandgap excitation and localized heat after absorption of sub-bandgap photons. This enables more efficient redox reactions with a less restricted redox potentials window and, thus, better utilization of the full solar spectrum. Despite these advantages, practical application remains elusive due to the mismatch between the short lifetime of the charge separation state (<ns) and the slower redox reaction rate (>μs). This mismatch results in a significant portion of the photogenerated charges recombining before participating in desired electrochemical energy storage reactions, leading to diminished overall efficiency. It is therefore highly important to develop molecular materials with intrinsic prolonged charge separation state and extrinsic effective mass-electron transfer to enable efficient coupled solar batteries for practical applications.In this Account, we begin with an introduction of the general solar-to-electrochemical energy storage concept based on molecular photoelectrochemical energy storage materials, highlighting the advantages of periodic oxidative donor-reductive acceptor porous aggregate structures that have synergistic implications on charge separation state lifetime extension and mass-electron transfer. We then present our earliest trial on the design and application of molecular photoelectrochemical energy storage materials, which stimulated our subsequent studies on tuning electron donor and acceptor structures for enhanced charge separation and diverse photoelectrochemical redox reactions. Moreover, we introduce the best practices in the design and assembly of various coupled solar battery devices, along with our literature contributions and progresses in solar-to-electrochemical energy storage efficiency (ηSES) over nearly the past decade. Finally, we conclude by highlighting the universality of our strategies as essential design principles, spanning from regulating long-lived charge separation states and photocoupled ion transfer processes in molecular materials to the construction of efficient coupled solar batteries. We offer perspectives on the synergy between photovoltage and redox potentials and the practical significance of 3D printing, providing key evaluation indicators for large-scale application. This Account provides molecular level insights for the construction of high-efficiency photoelectrochemical energy storage materials and guidance for practical solar-to-electrochemical energy storage applications.

Investigating BiMeVOx compounds as potential photoelectrochemical and electrochemical materials for renewable hydrogen production

In this study, BiMeVOx compounds (where Me: Co, Mo, Ce, Zr) were synthesized and characterized as potential photoelectrochemical materials for solar water splitting, the hydrogen evolution reaction (HER), and oxygen evolution reaction (OER). The analysis confirmed the successful formation of phase BiMeVOx compounds with the desired crystal structure. Among the tested materials, BiCoVOx(800) showed the highest photocurrent density (674 μA cm−2) and HER/OER activity (Tafel slope: HER = 100 mV dec−1 and OER = 75 mV dec−1), followed by BiMoVOx(800), BiCeVOx(800), and BiZrVOx(800). The superior photoelectrochemical performance of BiCoVOx(800) can be attributed to its unique electronic structure and optimized band alignment, which promote efficient charge separation and facilitate the water splitting and hydrogen evolution processes. The findings of this study highlight the promising potential of the synthesized BiMeVOx materials, particularly BiCoVOx, as efficient photoelectrochemical catalysts for water splitting. These results contribute to the advancement of renewable energy technologies and provide valuable insights for the design and development of novel photoactive materials.

Analysis of the Inhomogeneous Growth of Sputtered Black TiO2 Thin Films.

Black titanium dioxide (B-TiO2) is a highly active photoelectrochemical material compared to pure titanium dioxide due to its increased light absorption properties. Recently, we presented the deposition of thin-film B-TiO2 using an asymmetric bipolar reactive magnetron sputter process. The resulting samples exhibit excellent photoelectrochemical properties, which can be fine-tuned by varying the process parameters. In this article, results of morphological, electrical, and photoelectrochemical measurements are discussed to better understand the surprisingly high electrochemical activity of the films. In order to study the influence of the dynamic process on film formation, we use static sputtering with a fixed substrate covering the entire chamber area in front of the two targets. This allows the material composition of the sputtered film to be analyzed depending on its relative position to the targets. The results lead to the conclusion that the asymmetric bipolar sputtering mainly produces two phases, a transparent, nonconductive crystalline phase and a black, conductive amorphous phase. As a consequence, the dynamically sputtered samples are multilayers of these two materials. We discuss that the significantly better electrical and photoelectrochemical properties emerge from the inhomogeneous nature of the laminates, like also found in core-shell nanoparticles of B-TiO2.

The high-efficiency PEC material prepared by porphyrin grafted with Au nanoparticles embedded in porous carbon for PTK-7 detection

Photoelectrochemical (PEC) analysis has attracted accumulated attention on diagnosis of diseases and high-efficiency photosensitizers are urgently needed. In this work, N-doped sheet-like porous carbon (N-PC) was prepared by thermal stripping of Zn2+ from zeolitic imidazole framework-8 (ZIF-8), followed by in situ formation of gold nanoparticles (Au NPs) embedded in the N-PC (termed Au NPs@N-PC). Also, the zinc meso-tetra (4-carboxyphenyl) porphine (ZnP) behaved as photosensitizer, which was covalently linked with Au NPs@N-PC (ZnP-Au NPs@N-PC), achieving the 9.2-fold enhancement in the photocurrents by using dopamine (DA) as donor. Next, the PEC mechanism was strictly discussed by UV–vis diffuse reflectance (DLS) spectroscopy, fluorescence (FL) and density functional theory (DFT) calculations. By virtue of the excellent PEC property, a label-free “signal off” PEC aptasensor was constructed based on the ZnP-Au NPs@N-PC for ultrasensitive detection of protein tyrosine kinase (PTK-7). The established biosensor showed a wider linear range of 10.00 pg mL−1 to 1.00 μg mL−1 (R2 = 0.99) and a lower limit of detection (LOD, 1.42 pg mL−1), coupled by showing acceptable results for diagnosis of gliomas. Hence, this research opens a valuable avenue for synthesis of advanced photosensitizer and holds huge potential in biomedical field.

(Invited) Mulitjunction III-V Semiconductors for Photo-Electrochemical Hydrogen Production: Recent Progress in Efficiency, Durability, and Cost

Photo-electrochemical (PEC) hydrogen production is a route to carbon-free fuel that combines light absorption and water electrolysis into one device. Challenging targets for solar-to-hydrogen (STH) efficiency, durability, and semiconductor absorber costs must be realized for this approach to be economically competitive with other hydrogen production pathways. Research on PEC hydrogen production at the National Renewable Energy Laboratory (NREL) has focused on III-V semiconductor absorber materials because their tunable bandgaps, high photon conversion efficiencies, and ability to make multi-junction structures have resulted in the highest STH efficiencies yet demonstrated. This talk will focus on recent NREL results showing progress toward PEC hydrogen production efficiency, durability, and cost targets. Specifically, we have been able to improve theoretically achievable STH efficiency through bandgap engineering in multijunction devices. Photon management strategies to close the gap between theoretical and measured STH efficiency will also be discussed. Durability remains a significant challenge for III-V materials in a PEC environment. We will describe modifications to the semiconductor surface and the electrolyte constitution that can make the photoabsorber less susceptible to photocorrosion during operation. Finally, we will present preliminary results on III-V PEC materials synthesized via hydride vapor phase epitaxy, an alternative route to high-efficiency photoelectrodes that could potentially have much lower costs than the metalorganic vapor phase epitaxy method traditionally used. These improvements have yielded III-V PEC devices that are close to the STH efficiency target (17% vs. 25%) while the demonstrated durability and cost are still considerably far from their target values.

Fe Cluster Modified Co9 S8 Heterojunction: Highly Efficient Photoelectrocatalyst for Overall Water Splitting and Flexible Zinc-Air Batteries.

Designing bifunctional low-cost photo-assisted electrocatalysts for converting solar and electric energy into hydrogen energy remains a huge challenge. Herein, a heterojunction (Fe cluster modified Co9 S8 loaded on carbon nanotubes, Co9 S8 -Fe@CNT)for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is demonstrated. Benefiting from the good electronic conductivity and spatial confinement of the carbon skeleton, as well as the electronic structure regulation of the Fe cluster, Co9 S8 -Fe@CNT exhibits excellent catalytic performance with a low overpotential of 150mV for OER and 135mV for HER at 10mAcm-2 . Upon light irradiation, holes and electrons are generated in the valence band and conduction band of the Co9 S8 , respectively. Part of the charges are transferred to the interface to facilitate the catalytic reaction, while the remaining are transferred by the electrode. When working as a bifunctional catalyst for overall water splitting, the performance can reach 1.33V at under light conditions, which is significantly better than 1.52V in a dark environment. Theoretical calculations revealed lowered Gibbs free energy (∆GH *) of the heterojunction with the effect of Fe modification of Co9 S8 . This work sheds a new light in designing novel photoelectrochemical materials to convert solar and electric energy into chemical energy.

G-Quadruplex/Hemin-Mediated Polarity-Switchable and Photocurrent-Amplified System for Escherichia coli O157:H7 Detection.

The contamination of food by pathogens is a serious problem in global food safety, and current methods of detection are costly, time-consuming, and cumbersome. Therefore, it is necessary to develop rapid, portable, and sensitive assays for foodborne pathogens. In addition, assays for foodborne pathogens must be resistant to interference resulting from the complex food matrix to prevent false positives and negatives. In this study, hemin and reduced graphene oxide-MoS2 sheets (GMS) were used to design a near-infrared (NIR)-responsive photoelectrochemical (PEC) aptasensor with target-induced photocurrent polarity switching based on a hairpin aptamer (Hp) with a G-quadruplex motif. A ready-to-use analytical device was developed by immobilizing GMS on the surface of a commercial screen-printed electrode, followed by the attachment of the aptamer. In the presence of Escherichia coli O157:H7, the binding sites of Hp with the G-quadruplex motif were opened and exposed to hemin, leading to the formation of a G-quadruplex/hemin DNAzyme. Crucially, after binding to hemin, the charge transfer pathway of GMS changes, resulting in a switch of the photocurrent polarity. Further, G-quadruplex/hemin DNAzyme enhanced the cathodic photocurrent, and the proposed sensor exhibited a wide linear range ((25.0-1.0) × 107 CFU/mL), a low limit of detection (2.0 CFU/mL), and good anti-interference performance. These findings expand the applications of NIR-responsive PEC materials and provide versatile PEC methods for detecting biological analytes, especially for food safety testing.

Photodegradation of CuBi2 O4 Films Evidenced by Fast Formation of Metallic Bi using Operando Surface-sensitive X-ray Scattering.

CuBi2 O4 has recently emerged as a promising photocathode for photo-electrochemical (PEC) water splitting. However, its fast degradation under operation currently poses a limit to its application. Here, we report a novel method to study operando the semiconductor-electrolyte interface during PEC operation by surface-sensitive high-energy X-ray scattering. We find that a fast decrease in the generated photocurrents correlates directly with the formation of a metallic Bi phase. We further show that the slower formation of metallic Cu, as well as the dissolution of the electrode in contact with the electrolyte, further affect the CuBi2 O4 activity and morphology. Our study provides a comprehensive picture of the degradation mechanisms affecting CuBi2 O4 electrodes under operation and poses the methodological basis to investigate the photocorrosion processes affecting a wide range of PEC materials.

Photodegradation of CuBi2O4 Films Evidenced by Fast Formation of Metallic Bi using Operando Surface‐sensitive X‐ray Scattering

CuBi2O4 has recently emerged as a promising photocathode for photo‐electrochemical (PEC) water splitting. However, its fast degradation under operation currently poses a limit to its application. Here, we report a novel method to study operando the semiconductor‐electrolyte interface during PEC operation by surface‐sensitive high‐energy X‐ray scattering. We find that a fast decrease in the generated photocurrents correlates directly with the formation of a metallic Bi phase. We further show that the slower formation of metallic Cu, as well as the dissolution of the electrode in contact with the electrolyte, further affect the CuBi2O4 activity and morphology. Our study provides a comprehensive picture of the degradation mechanisms affecting CuBi2O4 electrodes under operation and poses the methodological basis to investigate the photocorrosion processes affecting a wide range of PEC materials.

A photoelectrochemical sensor based on CdTe NPs decorated copper‐tetramine phthalocyanine covalently grafted graphene oxide for p‐aminophenol determination

AbstractObjectivePara‐aminophenol (PAP) is a critical intermediate widely used in medicine, pharmaceutical, rubber, antioxidant, petroleum, and other fields, but it is harmful to the environment. A novel photo electrochemical (PEC) sensor was synthesized and applied to detect PAP based on the composite material of cadmium telluride nanoparticle (CdTe NPs)–decorated copper–tetramine phthalocyanine covalently grafted graphene oxide (CuTAPc‐Gr).Materials &amp; MethodsCopper–tetramine phthalocyanine (CuTAPc) has an excellent PEC conversion effect and narrow band. Graphene (Gr) has high mechanical stability and suitable bandgap. CuTAPc‐Gr was synthesized by chemical covalent bonding. And CdTe NPs@CuTAPc‐Gr composite was prepared by ultrasonic mixing method using CuTAPc‐Gr and CdTe NPs. The morphology and structure of the PEC materials were characterized using scanning electron microscopy and fourier transform infrared spectrometer. PAP contents were evaluated by the Time‐Current method. And the electron transfer rate of the PEC sensor was studied by electrochemical impedance spectroscopy methods.Results &amp; DiscussionCdTe NPs@CuTAPc‐Gr has excellent PEC properties. In the PAP analysis, distinct regular changes in the photocurrent within a linear range of 33.3–1330.0 nM were noted. The limit of detection was 15.5 nM. Acetaminophen, phloroglucin, and other substances did not affect PAP content determination. The water samples were analyzed using the proposed PEC sensor. The results show that the recoveries were in the range of 97.85%–99.58%, and relative standard deviations (RSDs) were less than 2%.ConclusionsThe PEC sensor exhibited excellent sensitivity, selectivity, and stability. The proposed method provides an effective strategy for constructing PEC sensors to detect PAP in water samples and a promising PEC platform for analyzing other small molecules.

WITHDRAWN: Editorial for a special issue on: (Photo) Electrochemical Materials and Devices

WITHDRAWN: Editorial for a special issue on: (Photo) Electrochemical Materials and Devices

Editorial for a special issue on: (Photo) electrochemical materials and devices

Editorial for a special issue on: (Photo) electrochemical materials and devices

Biomimetic sandwich assay of proteins with a photoelectrochemical sensor using molecularly imprinted targeting and self-ratiometric signaling

A novel photoelectrochemical (PEC) sensor based on dual-molecularly imprinted polymer (MIP) and self-ratiometric strategy was developed for measuring disease marker. The human papillomavirus 16 (HPV16) L1 protein was selected as a target model. The sensing elements contain TiO2 @Au as the PEC material, the MIP film as the primary artificial recognizer, and the alkaline phosphatase-labelled MIP nanoparticles (ALP-nanoMIPs) as the secondary artificial recognizer. Both MIPs were fabricated with a tailored and controllable process using merely a tiny epitope of the target protein as the templates. With the addition of L1 protein, a sandwich structure was formed and based on the dual-MIPs recognition. Ascorbic acid as the electron donor was produced and promoted the transient photocurrent response. Meanwhile, the steady photocurrent response decreased, arising from hinderance effect of the target protein rebinding for MIP film. This MIP sensor exhibited superior limit of detection (∼0.1 pg mL−1) and a broad linear range (0.28 pg mL−1 to 28 ng mL−1) for L1 protein. Good performance in terms of robustness, stability, selectivity, and repeatability was also confirmed. The designed MIP sensor has significant potential in extensive fields of low-cost antigen marker tests and healthcare screening.