Photoelectrochemical Properties Research Articles

Simple synthesis of K/P co-doped graphitic carbon nitride to enhance photocatalytic performance under simulated solar irradiation

The doping or co-doping of graphitic carbon nitride (g-C3N4) with other elements is a useful modification technique that overcomes the disadvantages of the base material and enhances its photocatalytic performance. In this study, K and P were successfully incorporated into g-C3N4 using a one-step, single-precursor (K2HPO4) synthesis method. The incorporation of K and P was confirmed using energy-dispersive X-ray spectrometry and wavelength-dispersive X-ray fluorescence spectrometry. Oxytetracycline (OTC) degradation rates were compared with and without elemental doping and with variation in the precursor content. In contrast to the low OTC degradation rate exhibited by pristine g-C3N4 (29.52 ± 0.03%), incorporating K and P into g-C3N4 greatly improved OTC degradation, with the sample produced using 100 mg of the precursor K2HPO4 (KPCN-100) achieving the highest degradation rate (99.43 ± 0.53%). The effects of the co-dopants K and P on the optical, photoelectrochemical properties, and band position of g-C3N4 were also investigated. Scavenging and N2 purging tests confirmed that reactive species, including O2•- (87.25%) and 1O2 (56.53%), played an important role in the degradation of OTC. In addition, several experimental parameters, including the presence of co-existing ions and humic acid, the pH level, the initial OTC concentration, and the photocatalyst dosage, were varied to better understand the photodegradation mechanisms at work within the KPCN-100 system. The stability of KPCN-100 and the toxicity assessment of the OTC intermediate were also conducted to evaluate their potential for environmental applications. Overall, this study demonstrates a simple synthesis method for the elemental co-doping of g-C3N4, offering an effective photocatalytic strategy that can greatly enhance the efficiency of OTC degradation.

The Influence of Dye Stimulation on Etched TiO2/ENR/PVC for Elevating Photocatalytic Activity and Photoelectrochemical Properties

AbstractThe application of polymer blends such as epoxidized natural rubber (ENR) and polyvinyl chloride (PVC) in immobilizing titanium dioxide (TiO2) photocatalysts has enticed many researchers. However, the presence of polymer limits the photocatalytic activity by hindering the surface‐active site of the immobilized TiO2. In this study, photoetching treatment with the presence of dye was successfully applied on the immobilized TiO2/ENR/PVC (TEP) to enhance the photocatalytic and photoelectrochemical (PEC) performance. Priorly, a dip coating technique was used to immobilize the TEP. The dye photoetching treatment was performed for several cycles to determine the reusability of the immobilized TEP. Furthermore, it demonstrated a significant enhancement of photocatalytic activity at which the best performance with the pseudo‐first‐order rate constant, k value of 0.1483 min−1 at the 13th cycle. The nonetched, photoetched TEP without dye and dye photoetched TEP have been characterized by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), X‐ray diffraction (XRD), thermal gravimetric analysis (TGA), and PEC. It is believed that the dye photoetched TEP will produce a good photocatalytic activity and PEC performance due to the presence of dye stimulant during the photoetching treatment.

Visible light-activated signal amplification PEC aptasensor for ultrasensitive zearalenone detection based on double Z-type BiOI/g-C3N4@Au/Bi2S3 heterojunctions

Zearalenone (ZEN), also known as F-2 toxin, can enter the body through the food chain and accumulate, leading to DNA break and an abnormal number of chromosomes. Therefore, it is crucial to develop a facile and sensitive method for detecting ZEN. Herein, a visible light-activated signal amplification photoelectrochemical (PEC) aptasensor for ultrasensitive detection of ZEN has been successfully constructed, exploiting the synergistic effect of the Z-type BiOI/g-C3N4/Au heterojunctions, Bi2S3 as a signal enhancer, and the remarkable affinity and specificity of aptamers. The PEC properties and electron transfer mechanism of the double Z-type heterojunctions were thoroughly investigated. When the aptamers captured the ZEN molecules, Bi2S3 and cDNA departed from the electrode, resulting in a reduction in the photocurrent signal. Therefore, the concentration of ZEN can be quantitatively analyzed by measuring the change in the photocurrent response. The constructed PEC aptasensor exhibited exceptional sensitivity and selectivity for ZEN in the concentration range of 0.1 fg⋅mL−1 ––1.0 ng⋅mL−1, with a detection limit of 0.087 fg⋅mL−1 (S/N = 3). Finally, the PEC aptasensor was successfully applied to detect ZEN in actual coix seed samples, providing some guidance for the development of PEC aptasensors for practical medicine monitoring.

Hierarchical Ordered Mesoporous Sr2Bi4Ti5O18 Microflowers with Rich Oxygen Vacancies In Situ Assembled by Nanosheets for Piezo-Photocatalysis.

The Aurivillius phase layered perovskite ferroelectric material Sr2Bi4Ti5O18 (SBTO) exhibits spontaneous polarization and piezoelectric properties, which confer significant potential for piezo-photocatalysis. Its ability to enhance electron-hole separation while providing excellent fatigue resistance positions it as a promising candidate in this field. Defects were introduced to improve the structural polarization and photoelectrochemical properties of SBTO. SBTO nanocrystals, featuring a mixed structure of hierarchically ordered mesoporous microflowers and nanosheets, were successfully synthesized via the hydrothermal method. The SBTO sample synthesized at a lower hydrothermal temperature displayed optimal oxygen vacancy concentration and exhibited superior piezoelectric-photo synergistic degradation activity for organic pollutants. Additionally, corona polarization increases the macroscopic polarization of the SBTO photocatalyst, promoting the separation of photogenerated carriers. Finite element simulations confirmed that a single flower-like SBTO structure generates a higher piezoelectric potential compared to a sheet-like morphology. In conclusion, integrating self-assembled hierarchical structure design, ferroelectric polarization, and defect engineering forms an effective strategy for achieving high-performance SBTO-based layered perovskite piezo-photocatalysts.

Structural and photoelectrochemical properties of fibrous silica-titania (FST) photocatalyst for water splitting

Photoelectrochemical (PEC) water splitting is an ecologically friendly technique that uses effective photoanodes to generate hydrogen (H2). The microemulsion approach was used to develop a distinctive form displaying fibrous silica-titania (FST) photoanode. We examined the photocatalytic attributes of FST, hematite (Fe2O3), and zinc oxide (ZnO). XRD, N2 adsorption-desorption, FESEM, TEM, FTIR, XPS, UV–vis/DRS, and EIS were used to investigate the FST, Fe2O3, and ZnO. By using these techniques, a bicontinuous concentric lamellar arrangement with an ample surface area has been developed within FST. Characterization results demonstrate that FST has superior catalytic activity when compared to Fe2O3 and ZnO. The FST photoanode has an improved photocurrent density of 11.75 mA/cm2 and a 14.1% Solar-to-hydrogen (STH %) efficacy, which is greater than ZnO and Fe2O3, which performed at 4.7 mA/cm2 and 2.8 mA/cm2 with 5.6% and 3.36% STH efficiency, respectively. Moreover, we also compared the Solar-to-hydrogen (STH %) effectiveness of FST with different of TiO2 photoanodes. We absorbed that the band gap is decreased when Ti is added to the silica matrix, which facilitates the formation of Si–Ti bonds. FST displays a remarkable closeness of its conduction band (CB) to the hydrogen reduction potential in comparison to ZnO and Fe2O3, allowing for quick electron transfer and rapid production of H2. The geometry of FST design provides a novel way for producing robust and exceptionally productive photoanodes for PEC water splitting.

Rapid Assembly of Ultrafine Palladium Nanoparticle-Decorated HOF-101 Triggered by Guest Enzyme Encapsulation.

Rapid enzyme immobilization is essential for enzyme catalysis and sensing applications, yet constructing effective immobilization systems is challenging due to the need to balance enzyme activity with the properties of the surrounding framework. Herein, taking glucose oxidase (GOx) as a model, a rapid and straightforward approach was presented for synthesizing palladium nanoparticles (PdNPs)-decorated GOx encapsulated in HOF-101 nanocomposite materials (designated as PdNPs/GOx@HOF-101) through an in situ photoreduction and enzyme-triggering HOF-101 encapsulation. The enzyme's surface residues trigger the nucleation of HOF-101 around it through the hydrogen-bonded bio interface, completing the self-assembly of HOF-101 in 0.5 h. Furthermore, the biocomposites loaded with ultrafine PdNPs show satisfactory photoelectrochemical (PEC) properties. As a proof-of-concept, a PEC biosensor was constructed by utilizing PdNPs/GOx@HOF-101 as a photoactive probe, which can quickly and sensitively detect glucose and simultaneously remain stable within the circumstance of 30-60 °C and pH 4-8. These attributes pave the way for diverse applications, including improved enzyme immobilization techniques, advanced biosensors, and more efficient biocatalytic processes.

Comparative Analysis of Anodized TiO2 Nanotubes and Hydrothermally Synthesized TiO2 Nanotubes: Morphological, Structural, and Photoelectrochemical Properties.

This study presents a comparative analysis of anodization and hydrothermal techniques for synthesizing TiO2 nanotubes directly on titanium foil. It emphasizes its advantages as a substrate due to its superior conductivity and efficient charge transfer. Optimized synthesis conditions enable a thorough evaluation of the resulting nanotubes' morphology, structure, and optical properties, ultimately assessing their photoelectrochemical and photocatalytic performances. Scanning electron microscopy (SEM) reveals differences in tube diameter and organization. An X-ray diffraction (XRD) analysis shows a dominant anatase (101) crystal phase in both methods, with the hydrothermally synthesized nanotubes exhibiting a biphase structure after annealing at 500 °C. UV-Vis and photoluminescence analyses indicate slight variations in band gaps (around 0.02 eV) and recombination rates. The anodized TiO2 nanotubes, exhibiting superior hydrophilicity and order, demonstrate significantly enhanced photocatalytic degradation of a model pollutant, amido black (80 vs. 78%), and achieve a 0.1% higher photoconversion efficiency compared to the hydrothermally synthesized tubes. This study underscores the potential advantages of the anodization method for photocatalytic applications, particularly by demonstrating the efficacy of direct TiO2 nanotube growth on titanium foil for efficient photocatalysis.

Anodic Synthesis of Highly Ordered TiO2 Nanotube Arrays: Role of Electrolyte Composition on the Structural, Morphological, Optical, and Photo-electrochemical Properties

The fluoride species present in two different anodizing electrolytes were used to produce TiO2 nanotube arrays (TiO2 NTAs) by simultaneous anodic reaction and chemical dissolution. In this investigation, two different electrolytes were used for the preparation; [Eth-TiO2 NAs: 95 ml ethylene glycol+0.5% NH4F+5 ml DI water] and [Gly-TiO2 NAs: 75 ml glycerine+0.5% NH4F+25 ml DI water]. The effects of the prepared electrolytes used in the synthesis of TiO2 nanotube arrays on structural element composition, morphology, and optical properties are the focus of this study and are characterized by X-ray diffraction (XRD), scanning electron microscopy field emission (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and UV-vis diffusion reflection spectroscopy (DRS), respectively. The photoelectrochemical properties of TiO2 NTAs prepared in different electrolytes were investigated. The photoelectrochemical performance of TiO2 NTAs in Na2SO3 (0.1 M) and Na2S (0.1) was examined under the light of 100 mW/cm2 from a xenon lamp. Comparing the photoelectrochemical (PEC) results of both electrolytes, we find that Eth-TiO2 NTAs contribute a wide surface area resulting in an enhanced PEC response. TiO2 NTs, which were prepared with Eth-TiO2 NTAs, exhibited the highest photocurrent density, 0.326 mA cm–2, and photoconversion efficiency (0.22%).

Role of Morphology on Zinc Oxide Nanostructures for Efficient Photoelectrochemical Activity and Hydrogen Production.

Energy generation today heavily relies on the field of photocatalysis, with many conventional energy generation strategies now superseded by the conversion of solar energy into chemical or thermal energy for a variety of energy-related applications. Global warming has pointed to the urgent necessity of moving away from non-renewable energy sources, with a resulting emphasis on creating the best photocatalysts for effective solar conversion by investigating a variety of material systems and material combinations. The present study explores the influence of morphological changes on the photoelectrochemical activity of zinc oxide nanostructures by exploiting electrodeposition and capping agents to control the growth rates of different ZnO facets and obtain well-defined nanostructures and orientations. A zinc nitrate (Zn (NO3)2) bath was used to electrodeposit ZnO nanostructures on an indium tin oxide glass (ITO) substrate at 70 °C with an applied potential of -1.0 V. Ethylenediamine (EDA) or ammonium fluoride (NH4F) were added as capping agents to the zinc nitrate bath. Extensive evaluation and characterization of the photoelectrochemical (PEC) capabilities of the resulting morphology-controlled zinc oxide nanostructures confirmed that altering the ZnO morphology can have positive impacts on PEC properties.

Preparation of PbS/TiO2 nanotube films for enhanced photoelectrochemical response and cathodic protection performance

Anodic oxidation method and sonication-assisted successive ionic layer adsorption and reaction (S-SILAR) process were used to prepare TiO2 nanotube films and PbS/TiO2 nanotube films. The effects of impregnation times on photoelectrochemical (PEC) performance of PbS/TiO2 nanotube films were systematically studied. The PEC properties were evaluated by UV–vis DRS, I-t, EIS and coupling potential. When PbS nanoparticles were impregnated for 15 times, the bandgap of PbS/TiO2 was narrowed to 1.4 eV, and the photocurrent density could reach 4.14 mA﹒cm−2, which increased by 12.8 times compared with TiO2. PbS nanoparticles loading onto TiO2 nanotube films is a simple and effective way to enhanced PEC response and cathodic protection performance.

Modification of solar energy and photoelectrochemical water splitting properties: using FTO/Er-TiO2/MAPbI3/CuPc/Au as modified photoelectrode

In the past decades, converting solar energy into hydrogen through photoelectrochemical water splitting has been attracted. Here, we designed a new FTO/Er-TiO2/MAPbI3/CuPc/Au photoanode with n-i-p structure for using in solar water splitting. Accourding to obtained PEC results, the FTO/Er-TiO2/MAPbI3/CuPc/Au photoanode has a photocurrent density of ∼9.8 mA cm−2 ( under a visible lamp with intensity of 100 mW cm−2 irradiation) compared to FTO/Er-TiO2/Au and FTO/Er-TiO2/MAPbI3/Au photoanodes with photocurrent density of 0.7 and 6.12 mA cm−2, respectively. This important enhancement is refered to the light absorption feature of Er-TiO2/MAPbI3 and a fast electron and hole transfer process in the Er-TiO2 and CuPc, respectively. The photoelectrochemical action of the photoelectrode is increased using erbium doping due to creation of oxygen vacancies and titanium (III) ions. Furthermore, in this research, we studided the power conversion efficiency (PCE) of FTO/Er-TiO2/MAPbI3/Au and FTO/Er-TiO2/MAPbI3/CuPc/Au solar cells. The results shown that the significant enhancement in photovoltaic properties can be observed by utilizing spin-coated CuPc nanoparticles (as hole transport layer) at least by 1.39% compared to the FTO/Er-TiO2/MAPbI3 perovskite solar cell.

An S-scheme TiO2/g-C3N4 nanocomposite effectively degrades phenanthrene under visible light

It is a challenge to effectively degrade phenanthrene (PHE) pollutants, which are widely present in aquatic environments, in order to reduce harm to humans and ecosystems. In this study, an S-scheme TiO2/g-C3N4 photocatalytic system is constructed using 0D TiO2 nanospheres and 2D g-C3N4 nanosheets for the removal of PHE from water under sunlight irradiation. The effects of irradiation time, quality ratio of TiO2 to g-C3N4, and cycle time on the performance of the TiO2/CN photocatalyst are investigated. The experimental results show that the ratio of TiO2 to g-C3N4 significantly affects the photocatalytic activity of the photocatalyst. Under the optimal ratio of TiO2 to g-C3N4 (50 % TiO2/CN), the apparent reaction rate constant for phenanthrene reached 0.00796 min−1, which is 11.5 times higher than that of pure TiO2 (0.00069 min−1). The tests of optical performance and photoelectrochemical properties further confirmed that the construction of the TiO2/g-C3N4 S-type photocatalyst successfully enhanced the spatial separation efficiency of photogenerated carriers and ensured a continuous supply of energy during the redox reaction process. Converting highly toxic phenanthrene into a non-toxic green degradation product provides an practical strategy for the safe treatment of PHE in aqueous environments through the use of visible-light-driven heterojunction photocatalysts. Additionally, the data collected on phenanthrene degradation in this study will provide valuable references for developing degradation methods for other PAHs, such as naphthalene, anthracene, and pyrene.

Low-cost fabrication methods of ZnO nanorods and their physical and photoelectrochemical properties for optoelectronic applications

Zinc Oxide (ZnO) nanorods have great potential in several applications including gas sensors, light-emitting diodes, and solar cells because of their unique properties. Here, three low cost and ecofriendly techniques were used to produce ZnO nanorods on FTO substrates: hydrothermal, chemical bath deposition (CBD), and electrochemical deposition (ECD). This study explores the impact of such methods on the optical, structural, electrical, morphological, and photoelectrochemical properties of nanorods using various measurements. XRD analysis confirmed the hexagonal wurtzite structure of ZnO nanorods in all three methods, with hydrothermal showing a preferred orientation (002) and CBD and ECD samples showing multiple growth directions, with average particle sizes of 31 nm, 34 nm, and 33 nm, respectively. Raman spectra revealed hexagonal Wurtzite structure of ZnO, with hydrothermal method exhibiting higher E2 (high) peak at 438 cm−1 than CBD and ECD methods. SEM results revealed hexagonal ZnO nanorods became more regular and thicker for the hydrothermal method, while CBD and ECD led to less uniform with voids. UV-vis spectra showed absorption lines between 390 nm and 360 nm. Optical bandgap energies were calculated as 3.32 eV, 3.22 eV, and 3.23 eV for hydrothermal, CBD, and ECD samples, respectively. PL spectra revealed UV emission band with a small intensity peak around 389 nm and visible emission peaks at 580 nm. Temperature dependent PL measurements for ZnO nanorods indicated that the intensities ratio between bound exciton and free exciton decreases with temperature increases for the three methods. Photocurrent measurements revealed ZnO nanorod films as n-type semiconductors, with photocurrent values of 2.25 µA, 0.28 µA, and 0.3 µA for hydrothermal, CBD, and ECD samples, and photosensitivity values of 8.01, 2.79, and 3.56 respectively. Our results suggest that the hydrothermal method is the most effective approach for fabricating high-quality ZnO nanorods for optoelectronic applications.

Study on the Electrochemiluminescence Emission Mechanism of HOF-14 and Its Multimode Sensing and Imaging Application.

A novel hydrogen-bonded organic framework (HOF-14) has attracted much attention due to its excellent biocompatibility and low toxicity, but its research in the electrochemiluminescence (ECL) field has not been reported. In this work, the annihilation-type and coreactant-type ECL emission mechanisms of HOF-14 were studied systematically for the first time. It was found that the ECL quantum efficiency of HOF-14/TEA coreactant system was the highest, which was 1.82 times that of Ru(bpy)32+/TEA. Further, the ECL emission intensity of HOF-14/TEA system could achieve colorimetric (CL) imaging of mobile phone. We also discovered that HOF-14 had superior photoelectrochemical (PEC) performance. Based on the above research results, a unique HOF-14-based multimode sensing and imaging platform was constructed. The antibiotic Enrofloxacin (ENR) was selected as the detection target, and the Cu-Zn bimetallic single-atom nanozyme (Cu-Zn/SAzyme) with excellent peroxidase (POD)-like activity was used to prepare quenching probes. When the target ENR was present, Cu-Zn/SAzyme quenching probes were introduced to the surface of HOF-14 by the dual-aptamer sandwich method. Cu-Zn/SAzyme could catalyze diaminobenzidine (DAB) to produce brown precipitations to quench the ECL, PEC, and CL signals of HOF-14, realizing multimode detection of ENR. This work not only discovered excellent ECL and PEC property of new HOF-14 material but also systematically studied the ECL emission mechanism of HOF-14, and proposed a novel multimode sensing and imaging platform, which greatly improved the detection accuracy of target and showed great contributions to the field of ECL analysis.

ZnS and Reduced Graphene Oxide Nanocomposite-Based Non-Enzymatic Biosensor for the Photoelectrochemical Detection of Uric Acid.

In this work, we report a study of a zinc sulfide (ZnS) nanocrystal and reduced graphene oxide (RGO) nanocomposite-based non-enzymatic uric acid biosensor. ZnS nanocrystals with different morphologies were synthesized through a hydrothermal method, and both pure nanocrystals and related ZnS/RGO were characterized with SEM, XRD and an absorption spectrum and resistance test. It was found that compared to ZnS nanoparticles, the ZnS nanoflakes had stronger UV light absorption ability at the wavelength of 280 nm of UV light. The RGO significantly enhanced the electron transfer efficiency of the ZnS nanoflakes, which further led to a better photoelectrochemical property of the ZnS/RGO nanocomposites. The ZnS nanoflake/RGO nanocomposite-based biosensor showed an excellent uric acid detecting sensitivity of 534.5 μA·cm-2·mM-1 in the linear range of 0.01 to 2 mM and a detection limit of 0.048 μM. These results will help to improve non-enzymatic biosensor properties for the rapid and accurate clinical detection of uric acid.

Fabrication of a 2D/2D g-C3N4@ZnTDA nanosheets catalyst for highly efficient degradation of 2,4-dibromophenol and improved flame retardancy of polyurethane foam

High charge separation and transfer efficiency are considered as key factors of photocatalysts in wastewater treatment applications. In this work, a high performance photocatalyst g-C3N4@ZnTDA was designed and applied through a facile solvothermal strategy. The microstructural, morphological, physicochemical, and photoelectrochemical properties of g-C3N4@ZnTDA were fully characterized. The photocatalytic activity of g-C3N4@ZnTDA nanoparticles under visible light source in degrading the 2,4-dibromophenol(2,4-dB) contaminants was also successfully studied. Additionally, the g-C3N4@ZnTDA composite demonstrates easy operation and good regeneration ability, making it highly promising for the efficient removal of phenolic pollutants from wastewater. Besides, a novel reutilization method for used catalyst as flame retardant and for PU foams was successfully testified. The MCN-3 as a fire-safety coating could reduce the heat release and improve flame retardancy of PU composites. This work opens a new window for valuable inspiration and structural design of reutilized MOF composites.

Complementary photoelectrochemical performances between dual heterojunctions and homojunction to achieve efficient solar water splitting of ZnIn2S4-based photoanode

The broken verge of carrier separation efficiency is invaluable factor to enhance photoelectrochemical performances of ZnIn2S4-based dual heterojunction. Hence, additional internal electric field is introduced when hexagonal/cubic ZnIn2S4 homojunction interface is used as medium to tandem Sb2S3/hexagonal-ZnIn2S4 and cubic-ZnIn2S4/Cu2S heterojunctions. The enhanced photoelectrochemical properties of Sb2S3/hexagonal/cubic ZnIn2S4/Cu2S are initiated through complementary properties of heterojunctions and homojunction components: (i) carrier separation efficiency verge of heterojunctions is broken to 56.29 % due to cooperation of homojunction, (ii) photoinduced carrier excitation energy homojunction is reduced to 2.06 eV with the modification of heterojunctions, (iii) built-in electric field is reinforced and electron delocalization of homojunction is enhanced by heterojunction, (iv) photoelectrochemical reaction sites of homojunction are increased through optimizing surface states effect of heterojunctions. As a result, the upgraded to 31.80 times higher water oxidization photocurrent density of 4.77 mA/cm2 is achieved by Sb2S3/hexagonal/cubic ZnIn2S4/Cu2S with decreased reaction overpotentials to 0.60 V. This work raises new thoughts on modified PEC performances of ZnIn2S4 via composite methods.

Effects of the phase transition on the photoelectrochemical properties of CuFe2O4 composite photoelectrode

In this study, CuFe2O4 was grown using various Cu:Fe source molar ratios. The morphological, structural, electrical, and photoelectrochemical properties of CuFe2O4 photoelectrodes with different structural phases based on molar ratios were analyzed. XRD and XPS were performed to systematically analyze the relationship between the structural and photoelectrochemical properties of the photoelectrode. XRD analysis revealed the phase transformation of CuFe2O4 from cubic to tetragonal phase and back to cubic phase as the Cu:Fe source molar ratio was varied. The crystallinity of Cu-rich cubic-CuFe2O4 was found to be superior to that of tetragonal-CuFe2O4. XPS analysis showed that the Cu-rich cubic-CuFe2O4 sample has higher Cu and Fe binding energies and more oxygen vacancies than the tetragonal-CuFe2O4 sample, which helps reduce carrier recombination. Additionally, cubic-CuFe2O4 samples prepared in Cu-rich conditions demonstrated high flat-band potential and low charge transfer resistance values. As a result, the cubic-CuFe2O4 photoelectrode sample under the Cu-rich condition exhibited a relatively high photocurrent density value. The highest photocurrent density value (-0.38mA/cm2 at -0.55 VSCE) was obtained with cubic-CuFe2O4 samples prepared under the Cu:Fe 3:1 condition.

In-situ synthesis of Fe phosphate layer on the porous hematite nanocube for efficient photoelectrochemical water splitting

Hematite (α-Fe2O3) is considered as an ideal photoanode material in photoelectrochemical (PEC) water splitting system due to its suitable band gap, excellent stability and abundant reserves. However, the actual PEC water oxidation performance of α-Fe2O3 is greatly limited by its severe charge recombination and sluggish water oxidation kinetics. Here, an in-situ generated Fe phosphate (Fe-Pi) coating strategy is applied on the surface of porous hematite nanocube (Fe2O3 NC) to realize PEC water oxidation effectively. The obtained Fe-Pi/Fe2O3 NC photoanode exhibits a remarkable PEC property with a photocurrent density of 2.7mAcm-2 at 1.23V vs. RHE, which was about 5.7-fold enlarged compared to the pristine nanorod-like hematite (Fe2O3 NR) photoanode. Detailed studies have shown that the porous Fe2O3 NC possesses an enhanced ability in light absorption and charge separation than the traditional Fe2O3 NR photoanode. In addition, the in-situ loading of Fe-Pi layer as a co-catalyst can not only effectively passivate the surface trapping states of Fe2O3 NC and suppress interfacial charge recombination, but also quickly extract the holes to participate in the water oxidation reaction. Our study suggests that the further surface modification based on morphological engineering is an effective strategy to improve the PEC performance of hematite.

Characterization of ZnSe Thin Film Electrodeposited at Room Temperature in Aqueous Medium without Complexing Agents

This study includes a simple electrodeposition technique for the fabrication of ZnSe thin film at room temperature and in an aqueous medium without additional complexing agents. Comprehensive analysis of the optical, structural, and morphological characteristics of the ZnSe thin film electrodeposited onto an ITO substrate was conducted using UV-Vis spectrometry, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and field emission–scanning electron microscopy (FE–SEM). Furthermore, the photoelectrochemical properties were evaluated through current-time (I-t) measurements and electrochemical impedance spectroscopy (EIS) under light on/off conditions. Mott-Schottky analysis was also performed to determine the conductivity type, carrier concentration, and flat band potential of the ZnSe thin film. Structural investigations revealed that the ZnSe thin film has a hexagonal structure, the longitudinal optical (LO) phonon mode, stretching and bending vibration modes of Zn-Se. The carrier type of the ZnSe thin film was identified as n- type semiconductor and photoelectrochemical measurements exhibited a photoresponse under the light illumination