Incident Photon-to-current Conversion Efficiency Research Articles

Thinned g-C3N4 nanosheets with microdopants of cucurbit[7]uril to improve photoelectrochemical water-splitting

Utilizing solar energy to generate hydrogen through photoelectrochemical (PEC) water splitting is considered as the most efficient method and sustainable pathway. Graphitic carbon nitride (g-C3N4), as a candidate for photoelectrochemical catalysts, exhibits the drawbacks including small specific surface area and high complexity of photogenerated electron-hole pairs. With supramolecular encapsulation of melamine guest within cucurbit[7]uril, a new process for thinned and nitrogen-doped g-C3N4-0.04 % nanosheets are developed, and the photoelectrocatalytic activity is obviously improved on the surface. A photocathode with the prepared g-C3N4-0.04 % nanosheets produce more than twice efficiency of pristine g-C3N4 for water splitting, and the incident photon-to-current conversion efficiency (IPCE) is increased by a factor of about 10 under simulated conditions of sunlight at AM 1.5 G (100 mW/cm2). The improved performance should be the results of the thinned layers by introduction of the macrocyclic compound in g-C3N4 nanosheets, which reduce the charge transfer resistance, and inhibit the complexation of the photogenerated electron pairs, to prolong the lifetime of the electron, and facilitate the ability of the electron transport with an increase in current. On the other hand, the specific surface area is improved in the g-C3N4-0.04 % nanosheets to expose more reactive sites, and the microdopant of cucurbit[7]uril provides more active nitrogen sites, to enhance the photocatalysis.

Novel synthesis of reduced PdO-WO3 hybrids for enhanced photoelectrochemical water splitting

In this study, a novel synthesis approach for WO3 nanoparticles and their hybrids is proposed, followed by an investigation of their photoelectrochemical performance for water splitting applications. The surface modification of WO3 nanoparticles is carried out by immersing them in a Pd precursor solution, followed by calcination to obtain PdO-WO3 hybrid nanoparticles. Subsequently, the PdO-WO3 is reduced in a hydrogen (H2) environment to prepare PdOx-WO3-y hybrid material. XPS analysis revealed that H2 reduction converts residual metallic Pd to PdH and simultaneously generates oxygen vacancy defects in WO3 hybrid nanoparticles, as confirmed by EPR analysis. Additionally, TPR analysis further confirms the H2-induced reduction in the PdO-WO3 hybrid at a lowered temperature of 150 °C. The optical band gap energy of PdOx-WO3-y hybrid nanoparticles is slightly reduced (by 0.06 eV) compared to that of the PdO-WO3 reference sample. Photoelectrochemical measurements were conducted to assess the impact of these tailored modifications on the performance of conventional PdO-WO3 nanoparticles. The reduced PdOx-WO3-y catalyst exhibits an approximatly ∼22 % improvement in incident photon-to-current conversion efficiency (IPCE), over the unreduced PdO-WO3. The PEC efficiency improvement was attributed to the composite electronic structure changes introduced during the annealing process. Mott-Schottky measurements confirm that the reductive treatment consolidates the material’s two distinct flat band potentials (Efb) into with a single intermediate energy level and increases the charge carrier concentration. This study presents a straightforward method to generate oxygen vacancy defects in hybrid metal oxides and provides a convenient method for band gap engineering for photoelectrocatalytic applications.

2D/2D heterojunction of SnS2/g-C3N4 nanocomposite photoelectrode for improved photoelectrochemical water splitting performance

This work presents the synthesis of photoelectrode composed of tin disulfide (SnS2) coupled with graphitic carbon nitride (g-C3N4) to improve the efficiency of photoelectrochemical (PEC) water splitting. The SnS2/g-C3N4 nanocomposite was prepared using the chemisorption process, and the photoelectrode was prepared of thin film deposited on fluorine-doped tin oxide (FTO) substrate employing the spray coating technique. Photocurrent density for SnS2/g-C3N4-20 nanocomposite is ∼ 1.0 mA/cm2 at 1.0 V versus the Ag/AgCl reference electrode, which is ∼ 5 times the value for pristine SnS2 photoelectrode. The maximum PEC performance is achieved for 20 wt% of g-C3N4 in SnS2/g-C3N4-20 nanocomposite. The incident photon-to-current conversion efficiency (IPCE) value of the SnS2/g-C3N4 −20 nanocomposite exhibits an enhancement of ∼ 4.3-fold compared to bare SnS2. This enhancement in PEC performance can be due to type-II heterojunction formed at the interface of SnS2 and g-C3N4, which facilitates efficient charge separation and reduces recombination losses. This enhanced photocurrent density is supported by Mott-Schottky studies and electrochemical impedance spectroscopy (EIS) results. This work elucidates the significant potential of SnS2/g-C3N4 heterostructures as efficient and durable photoelectrodes for renewable hydrogen production, contributing towards the advancement of sustainable energy technologies.

Plasmon-induced electron transportation in heterostructure N-rGO/NiFe-LDH@Au with enhanced photoelectrochemical water oxidation

Facile design and fabrication of an ideal heterointerface model is considered as a significant advancement towards photoelectrochemical (PEC) water splitting efficiency. Here, we detail the incorporation of plasmonic Au nanoparticles into N-doped reduced graphene oxide/NiFe-layered double hydroxide (N-rGO/NiFe-LDH) interface by cost-effective coprecipitation-photoreduction method and photoelectrode assemblage via drop casted technique for enhanced PEC water oxidation. Au nanoparticles efficiently harvest the light energy upon plasmonic excitation and transfer the energy towards contacted NiFe-LDH and N-rGO, thereby promoting PEC performances. In comparison to N-rGO/NiFe-LDH, the as-obtained N-rGO/NiFe-LDH@Au composite exhibits 1.46 fold times enhancement in photocurrent density (5.7 mA/cm2 at 1.23 V vs RHE) and considerable cathodic shift of 20 mV at onset potential of 0.18 V for PEC water oxidation. Additionally, N-rGO/NiFe-LDH@Au exhibits incident photon to current conversion efficiency (IPCE) of 10 % and better photostability of more than 6 h for boosted water splitting. The incorporation of Au nanoparticles significantly augmented the photoactivity as apparent from the photocurrent density assessment. The improved PEC performance of N-rGO/NiFe-LDH@Au photoelectrode is accredited to the surface plasmon resonance (SPR) induced electron transfer process and heterostructure configuration holding numerous defect sites for smooth charge transportation. This fabrication approach is quite a simplistic method to enlarge the optical behavior and effective performance of the PEC system and also provide guidance to assemble other sophisticated materials suitable for the energy conversion process.

Structural, spectroscopic and improved photoelectrochemical properties of TiO2/C composites with anatase/brookite matrix, prepared by air-thermolysis of microspherical titanium glycolate

X-ray powder diffraction, Raman spectroscopy, HRTEM, electron diffraction and differential thermal analysis methods were used to study structural and spectroscopic properties and thermal stability of the products obtained by air-thermolysis of Ti-glycolate in the temperature range 300–450°С. TiO2/C composites were obtained, which have anatase/brookite matrix with a variable degree of crystallinity and contain different contents of brookite and free polymeric-like carbon with COO− groups. It was found that the residual content of carbonaceous component and the intensity of exothermal decomposition of Ti-glycolate have an effect on the formation of brookite-rich TiO2 matrix. Correlations between the phase composition and the free carbon content suggest that during crystallization brookite/carbon nanoparticles are more stable than anatase/carbon nanoparticles. PEC tests demonstrated that the composite photoanode, which has the greatest degree of crystallinity, the optimal carbon content and is most enriched with brookite, exhibits the greatest incident photon-to-current conversion efficiency (IPCE), and its IPCE peak value is twice as great as the IPCE peak value for Degussa P25. The increased IPCE value is associated with the preferable formation of carbon/brookite/anatase heterostructures. The carbon component has an optical gap of approx. 1.1 eV, and at the optimal contents it ensures efficient photogeneration and transfer of electrons into the conduction band of brookite and then into the conduction band of anatase. HRTEM study demonstrated the formation of such heterostructure with anatase/brookite heterojunction.

2D nanosheet SnS2 solution-processed photoanodes: Unveiling enhanced visible light absorption for solar fuels applications

The scale-up of photoelectrochemical water splitting and CO2 reduction is currently hindered by the excessive band gap of metal oxide photoanodes. Metal sulfides 2D nanostructured morphology offer improved optoelectronic properties and catalytic capabilities in the oxygen evolution reaction (OER). This study demonstrates for the first time visible spectra absorption capabilities of SnxSy photoanodes, fabricated by facile non-vacuum techniques and post-annealed in a sulfur atmosphere, yielding SnS2 multilayer nanosheets with visible-light absorption down to 900 nm wavelengths. Optimal annealing (500 °C) resulted in >1 V photovoltages, photocurrents surpassing 1.6 mA/cm2 at 1.23VRHE, incident photon-to-current conversion efficiency (IPCE) of 75% at 330 nm. Photon conversion in the 500–900 nm range (down to 1.37 eV) is correlated with phase transformation from orthorhombic α-SnS to Sn2S3 and further hexagonal SnS2. IPCE is key for describing effective phase transformation and photon conversion at wavelengths below the dominant direct band gap for the SnS2, suggesting potential indirect transitions or confinement in the low-dimensional nanosheets. SnS2 nanosheets fabricated by solution-processed means, hold great potential for large-scale, cost-effective, and efficient photoelectrochemical devices.

Ideal Structures of Isolated BiVO4 Nanoparticles on WO3 Nanocorals to Enhance Photoelectrochemical Hydrogen Evolution

Metal oxide nanoparticles (NPs) of n-type semiconductors have recently garnered significant attention in the photoelectrochemical (PEC) field. In this study, isolated BiVO4 NPs on anodized WO3 nanocorals are investigated with respect to the formation mechanism of the NPs and the correlation between particle size and PEC efficiency. The sizes and distances of the BiVO4 NPs on the WO3 nanocorals are controlled via spin-coating and heat-treatment. The optimized BiVO4 NPs, with ideal sizes of 10 nm and distances of 100 nm between them, exhibit satisfactory electron and hole diffusion lengths, suppressing electron–hole recombination and promoting the exposure of WO3 to ultraviolet light. Furthermore, high-quality BiVO4, without the formation of by-products due to the optimized concentrations of Bi and V in the precursor solution, results in a 2.3-fold higher photocurrent density and H2 production, and a 6-fold higher incident photon-to-current conversion efficiency (IPCE) compared to those of pristine WO3 nanocorals.

Scaling-Up of Solution-Processable Tungsten Trioxide (WO3) Nanoparticles as a Hole Transport Layer in Inverted Organic Photovoltaics

We reported the comparative studies of the optimization of solution-processable tungsten trioxide (WO3) as a hole transporting layer (HTL) in inverted organic photovoltaics (OPVs) using spin coating, slot-die coating, and spray coating technologies for scaling-up applications. To facilitate the technology’s transition into commercial manufacturing, it is necessary to explore the role of scalable technologies for low-cost and efficient device fabrication. We investigated the role of diluting WO3 with isopropanol as an HTL in inverted OPVs to solve the issue of poor wettability of the hydrophobic surface of the PBDB-T: ITIC bulk heterojunction layer. The optimal dilution ratios of WO3 with isopropanol were 1:4, 1:4 and 1:8 with spin coating, slot-die coating and spray coating techniques, respectively. We evaluated the device performance by conducting a current density–voltage (J-V) analysis, incident photon-to-current conversion efficiency (IPCE) measurements, and ultraviolet–visible (UV-Vis) absorbance spectra for various WO3 concentrations. The J-V characteristics revealed that slot-die coating resulted in the highest performance, followed by the spray coating technology. We further investigated the impact of the annealing temperature on device performance for both slot-die- and spray-coated diluted WO3. The highest device performance was achieved at an annealing temperature of 120 °C for both coating technologies. This research offers valuable insights into the scalable fabrication of inverted OPV devices, paving the way for cost-effective and efficient large-scale production.

1,1'-Bis-(diphenylphosphino)ferrocene appended d8- and d10-configuration based thiosquarates: the molecular and electronic configurational insights into their sensitization and co-sensitization properties for dye sensitized solar cells.

Three new d8- and d10-configuration based 1,1'-bis-(diphenylphosphino)ferrocene (dppf) appended thiosquarates complexes with general composition [M(mtsq)2dppf] (M = Ni2+ (NiL2); Zn2+ (ZnL2) and Cd2+ (CdL2)) (mtsq = 3-ethoxycyclobutenedione-4-thiolate) have been synthesized and characterized spectroscopically as well as in case of NiL2 by single crystal X-ray diffraction technique. The single crystal X-ray analysis reveals square planar geometry around Ni(II) in NiL2, where Ni(II) coordinates with two sulfur centres of two mtsq ligands in monodentate fashion and two phosphorus of a dppf ligand in chelating mode. The supramolecular architecture of NiL2 is sustained by intermolecular C-H⋯O interactions to form one-dimensional chain. Further, the application of these newly synthesized complexes as sensitizers and co-sensitizers/co-absorbents with ruthenium based N719 sensitizer in dye-sensitized solar cells (DSSCs) have been explored. The DSSC set-up based on NiL2 offers best photovoltaic performance with photovoltaic efficiency (η) 5.12%, short-circuit current (Jsc) 11.60 mA cm-2, open circuit potential (Voc) 0.690 V and incident photon to current conversion efficiency (IPCE) 63%. In co-sensitized DSSC set-up, ZnL2 along with state-of-the-art N719 dye displays best photovoltaic performance with η 6.65%, Jsc 14.47 mA cm-2, Voc 0.729 V and IPCE 69%, thereby showing an improvement by 15.25% in photovoltaic efficiency in comparison to the photovoltaic efficiency of N719 sensitized DSSC set-up. Variation in co-sensitization behaviour have been ascribed to the differences in the excited state energy level of co-sensitizers. The ZnL2 and CdL2 have a higher energy level position than N719 dye, allowing efficient electron transfer to N719 during light irradiation, while excited state of NiL2 is lower than N719 dye, preventing photoexcited electron transfer to N719, resulting in its lowest overall efficiency among the three co-sensitized DSSC setups.

Enhancing photoelectrochemical performance and stability of Ti-doped hematite photoanode via pentanuclear Co-based MOF modification.

Modifying photoanodes with metal-organic frameworks (MOFs) as oxygen evolution reaction (OER) cocatalysts has emerged as a promising approach to enhance the efficiency of photoelectrochemical (PEC) water oxidation. However, designing OER-active MOFs with both high photo- and electrochemical stability remains a challenge, limiting the advancement of this research. Herein, we present a facile method to fabricate a MOF-modified photoanode by directly loading a pentanuclear Co-based MOF (Co-MOF) onto the surface of a Ti-doped hematite photoanode (Ti:Fe2O3). The resulting Co-MOF/Ti:Fe2O3 modified photoanode exhibits an enhanced photocurrent density of 1.80mA∙cm-2 at 1.23V, surpassing those of the Ti:Fe2O3 (1.53mA∙cm-2) and bare Fe2O3 (0.59mA∙cm-2) counterparts. Additionally, significant enhancements in charge injection and separation efficiencies, applied bias photon-to-current efficiency (ABPE), incident photon to current conversion efficiency (IPCE), and donor density (Nd) were observed. Notably, a minimal photocurrent decay of only 5% over 10h demonstrates the extraordinary stability of the Co-MOF/Ti:Fe2O3 photoanode. This work highlights the efficacy of polynuclear Co-based MOFs as OER cocatalysts in designing efficient and stable photoanodes for PEC water splitting applications.

Amorphous cobalt boride exploring as the first first-row transition-metal-based metallic photocatalyst for efficient water splitting over 800 nm

Semiconductors often have limited photocatalytic water-splitting performances owing to the narrow light absorption and low effective carrier density. In response to these challenges, we report the discovery of metallic amorphous cobalt boride (Co2B) as the first first-row transition metallic photocatalyst. It was prepared via a simple chemical reduction method and performs efficient water splitting spanning the UV, visible light and near-infrared region (NIR) via interband transitions. It achieves bifunctional water splitting activities with H2 evolution rate of 202.3 μmol h−1 g−1 and O2 evolution rate of 74.8 μmol h−1 g−1, superior to the existing (semi-)metallic photocatalysts. The material shows over 1 % apparent quantum efficiency (AQE) and 20 % incident photon to current conversion efficiencies (IPCE) at the NIR region >800 nm. Theoretical and photophysical experimental studies synergistically confirm that the metallic nature with high carrier concentrations and amorphous structure with abundant active sites contribute to the good water splitting performance of Co2B. This research sets the foundation for the utilization of highly efficient transition metal-based metallic photocatalysts in photocatalysis across the entire solar spectrum.

Fabrication of ambient processed carbon-based inorganic silver bismuth iodide solar cells without any expensive hole transport materials

Recently, tremendous progress has been made in inorganic–organic hybrid lead halide perovskite solar cells (PSCs). Still, most of the reported high-efficiency PSCs were made with harmful lead (Pb), which is one of the major obstacles to large-scale adoption. Silver bismuth iodide (AgBiI4) light absorbers have been identified as promising lead-free and low-toxic metal-halide materials for solar cell applications. Here, we present hole transport material (HTM) and lead-free carbon-based inorganic Rudorffite (AgBiI4) solar cells, which can be prepared by simple spin-coating using silver iodide and bismuth iodide precursors under ambient conditions. Powder X-ray diffraction (XRD), UV–visible absorption, and field emission scanning electron microscopy (FESEM) studies were used to characterize the deposited films. The performance of the fabricated device was studied using incident photon-to-current conversion efficiency (IPCE) and current density–voltage (J-V) characteristics. Electrochemical impedance spectroscopy (EIS) was used to investigate the charge transfer process at the interface of the fabricated device. Under standard illumination test conditions, the fabricated device showed a photoelectric conversion efficiency (PCE) of 1.04%. The devices also have good stability and retained 96% of their initial PCE after 200 hrs of storage in ambient conditions. This work demonstrates the potential of HTM-free, ambient processable, and lead-free Rudorffite stable solar cells.

MoO3/BiVO4 heterojunction modified with cobalt-manganese layered double hydroxide cocatalyst for photoelectrochemical water oxidation

To improve the charge recombination and poor oxygen evolution reaction (OER) kinetics of BiVO4, in this paper, a high-performance CoMn-LDH/MoO3/BiVO4 photoanode was synthesized by a simple electrodeposition and calcination method. CoMn-LDH/MoO3/BiVO4 shows a photocurrent density of 3.78 mA cm−2 at 1.23 V vs. RHE, which is 3.78 times higher than that of pure BiVO4 with negative shift onset potentials of 330 mV. The maximum applied bias photon-to-current efficiency (ABPE) and incident photon-to-current conversion efficiency (IPCE) are 1.24 % and 55.5 %, respectively, which are 13.8 and 12.5 times higher than those of pure BiVO4. In-depth studies demonstrate that the MoO3/BiVO4 heterojunction can better drive the transfer of photogenerated carriers and suppress bulk charge recombination, CoMn-LDH improves the OER kinetics and broadens the absorption of visible light, their synergistic effect significantly enhances charge separation and light harvesting of BiVO4. This work provides a facile electrodeposition method to fabricate highly efficient photoanodes for solar-driven water splitting.

Photoelectrocatalytic based simultaneous removal of multiple organic micro-pollutants by using a visible light driven BiVO4 photoanode

In this research, photoelectrocatalytic (PEC) based advanced oxidation process (AOP) was studied for the removal of multiple OMPs through an oxidative mechanism. This study investigated the application of a BiVO4 photoanode in simultaneous removal of three selected OMPs: acetaminophen (ACT), benzotriazole (BTA) and propranolol (PRO). This study was carried out in demineralized water with a starting concentration of each organic micro-pollutant (OMP) at 45 μg L−1. In order to fabricate BiVO4 photoanodes, a facile and effective dip-coating method was used to deposit BiVO4 photocatalytic layers on fluorine doped tin oxide (FTO) substrate. UV–vis diffusive reflectance spectroscopy, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) confirmed the successful fabrication of porous BiVO4 photoanode having an absorbance edge at around 526 nm. The fabricated photoanode showed incident photon to current conversion efficiency (IPCE) of 9.23% (λmax=445 nm) under 1 Sun standard illumination. Application of the fabricated photoanodes for the simultaneous removal of ACT, PRO and BTA at an applied voltage of 1 V (vs Ag/AgCl) under solar simulated light resulted in 99% removal of both ACT and PRO, and 70% removal of BTA. The first order rate coefficients and half-life times of ACT and PRO were about three times higher than those of BTA.

Heterojunction of TiO2 nanotubes arrays/Bi2Se3 quantum dots as an effective and stable photoanode for photoelectrochemical H2 generation

The use of semiconductor materials to split water through photoelectrochemical (PEC) processes is a remarkable technique that can transform solar energy into chemical energy, such as H2, in one step. For enhanced H2 generation, efficient separation of electron–hole (e−/h+) pairs and high photogenerated electron conductivity are required for photoanode substrates. In this study, an effective type II heterojunction between Bi2Se3 quantum dots (QDs) and TiO2 nanotube arrays (TNTAs) was constructed by depositing Bi2Se3 QDs on the TNTAs surface. The performance for PEC H2 generation was also investigated. The TNTAs/Bi2Se3 QDs demonstrated the highest photocurrent density of 1.75 mA cm−2, which is 3.8 times greater than bare TNTAs (0.46 mA cm−2) at 1.23 V vs. RHE. They also achieved a high hydrogen generation quantity of 355.8 μmol after 5 h, which is 3.3 times greater than bare TNTAs (105.3 μmol) at 1.23 V vs. RHE. TNTAs and TNTAs/Bi2Se3 QDs photoanodes both exhibited excellent stability for over 7 h. Compared with bare TNTAs, the TNTAs/Bi2Se3 QDs photoanode demonstrated a higher incident photon-to-current conversion efficiency (IPCE) in the UV region and expanded the light response to the visible region due to its lower charge recombination and larger visible light absorption. The exceptional performance of the TNTAs/Bi2Se3 QDs photoanode is due to its proper bandgap energy, which improves the visible light absorption, and its effective charge carrier transfer, which alleviates the recombination of e−/h+ pairs. The modification of TNTAs with Bi2Se3 QDs as a promising metal chalcogenide for improving visible light absorption and PEC water splitting performance has not yet been studied. Therefore, this work paves the way for a facile approach to construct a stable and high-performance photoanode for PEC H2 generation.

Stable metal-organic framework (MOF) integrated BCZT for improved photo-electrochemical water splitting

We report enhancement in the photo-electrochemical properties of Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) coupled with a copper-based metal–organic framework (Cu-MOF). The optical bandgap (Eg) of BCZT reduces to 2.2 eV from 2.8 eV after Cu-MOF coupling, leading to increased visible light absorption in the Cu-MOF/BCZT composite. The photo-current was enhanced from 20 μA/cm2 to 80 μA/cm2(∼4 times higher) in the Cu-MOF/BCZT composite under visible light illumination. The enhancement in the photo-current was well supported by enhancement in incident photon to current conversion efficiency (IPCE), electrochemical impedance spectroscopy (EIS), and Mott-Schottky measurements, respectively. The porous structure of the Cu-MOF enhances change transfer properties in the Cu-MOF/BCZT composite,which is a critical factor for the observed enhancement in the photo-electrochemical properties. This work provides a novel strategy for combining MOFs with photo-absorbing materials to design future solar-to-hydrogen conversion devices.

CuFeO2/Cu Photoelectrode Modified with SrTiO3 Perovskite for Efficient Hydrogen Generation from Sanitation Water

We prepared a perovskite material, copper-doped strontium titanate (Cu-SrTiO3), using the chemical bath deposition method and cast it on a CuFeO2/Cu photoelectrode to generate hydrogen from sanitation water splitting. This preparation method considers a simple mass product and does not depend on complex techniques. The prepared perovskite materials had a compact nano-/microstructure. Both CuFeO2 and Cu-SrTiO3/CuFeO2 exhibited excellent optical properties, with bandgap values of 1.4 and 1.26 eV, respectively. Here, the prepared CuFeO2 and Cu-SrTiO3 thin films are used as photoelectrodes for hydrogen generation, and their current-voltage relationship is analyzed under various conditions, such as different light intensities, wavelengths, and temperatures. This approach is promising for using wastewater as a source of hydrogen gas without requiring any additional electrolyte, making it a dual-purpose approach for both hydrogen generation and wastewater treatment. Through the electrochemical study, increasing the light intensity from 25 to 100 mW.cm-2 resulted in a corresponding increase in the produced J ph values from -1.02 to -1.292 mA.cm-2. Similarly, the J ph values increased from -1.25 to -1.91 mA.cm-2 as the temperature increased from 30 to 70°C. We also calculated all thermodynamic parameters, the quantum efficiency (QE), and incident photon to current conversion efficiency (IPCE). For the Cu-SrTiO3/CuFeO2/Cu photoelectrode, the activation energy ( E a ) value was 14.14 kJ mol-1, while the Δ H ∗ and Δ S ∗ values were 11.46 kJ·mol-1 and 34.9 kJ-1·mol-1, respectively. Additionally, the IPCE value was 3.31%. The prepared photoelectrode showed high stability and low cost, making it a potential candidate for industrial applications.

Fabrication of Hematite Photoanode Consisting of (110)-Oriented Single Crystals.

In this work, α-Fe2 O3 photoanode consisted of (110)-oriented α-Fe2 O3 single crystals were synthesized by a facile hydrothermal method. By using particular additive (C4 MimBF4 ) and regulation of hydrothermal reaction time, the Fe-25 consisted of a single-layer of highly crystalline (110)-oriented crystals with fewer grain boundaries, which was vertically grown on the substrate. As a result, the charge separation efficiency and photoelectrochemical (PEC) performance of Fe-25A (Fe-25 after dehydration treatment) have been greatly improved. Fe-25A yields a photocurrent of 1.34 mA cm-2 (1.23 V vs RHE) and an incident photon-to-current conversion efficiency (IPCE) of 31.95 % (380 nm). With the assistance of cobalt-phosphate water oxidation catalyst (Co-Pi), the PEC performance could be further improved by enhancing the holes transfer at electrode/electrolyte interface and inhibiting surface recombination. Fe-25A/Co-Pi yields a photocurrent of 2.67 mA cm-2 (1.23 V vs RHE) and IPCE value of 50.8 % (380 nm), which is 3.67 times and 2.39 times as that of Fe-2A/Co-Pi. Our work provides a simple method to fabricate highly efficient Fe2 O3 photoanodes consist of characteristic (110)-oriented single crystals with high crystallinity and high quality interface contact to enhance charge separation efficiencies.

Synthesis of CuInS2 thin film photocathode with variation of sulfurization sources and Pt-In2S3 modification for photoelectrochemical water splitting

CuInS2 thin films have been successfully synthesized from the electrodeposition of copper (Cu), indium (In), and sulfurization on a molybdenum glass substrate as a water splitting photocathode. The effect of various sources of sulfurization with thiourea, sulphur, and H2S and modification with Pt-In2S3 on the character and performance of the material was observed. The success of the synthesis was confirmed by the typical peaks of 28.2, 46.8, and 55.4° on XRD, the presence of Cu, In, S elements on SEM-EDX analysis, the appearance of peaks of 298 cm−1 on Raman analysis, and the detection peaks of Cu 2p, In 3d, and S 2p with XPS analysis. Meanwhile, performance effectiveness and photoelectrochemical properties were analysed with photocurrent linear sweep voltammetry (LSV), applied bias photon-to-current efficiency (ABPE), and incident photon-to-current conversion efficiency (IPCE). Variations of sulfurization sources give different character and photocurrent results due to differences in the existing reaction mechanisms. While the modification treatment with Pt-In2S3 increased the resulting photocurrent. Sulfurization with H2S and modification of Pt-In2S3 gave the best results with a photocurrent of 18 mA cm−2, an efficiency of 3% ABPE, 47.2% IPCE, was evolved 467 μmol H2 and 230,1 μmol O2. This shows good potential as a water splitting material to produce environmentally friendly hydrogen fuel.

Titanium dioxide (TiO2) and gel-polymer solar cells

This research focuses on the study of semiconductor-based solar cells utilizing titanium dioxide (TiO2) and gel-polymer electrolytes. The technology for preparing the electrolytes used in these solar cells has been developed, encompassing both liquid and gel polymer electrolyte compositions. The electrochemical impedance method is employed to determine important parameters such as diffusion coefficient, mobility, and charge carrier concentration in both liquid and gel-polymer electrolytes. Experimental results are compared with theoretical calculations utilizing the electrochemical impedance spectroscopy graph. Moreover, the photon-to-current conversion efficiency of the semiconductor-based solar cells is determined using the Incident Photon to Current Conversion Efficiency (IPCE) method, covering a wavelength range of 300 nm to 900 nm.