Amount Of Dye Loading Research Articles

Fabrication and Enhanced Performance Evaluation of TiO2@Zn/Al-LDH for DSSC Application: The Influence of Post-Processing Temperature.

A sequence of dye-sensitized solar cells is proposed, utilizing TiO2@Zn/Al-layered double hydroxide (LDH) as their starting materials, in which Ruthenizer N719 was used as a photon absorber. The anticipated system was turned into sheet-like TiO2@mixed metal oxide (MMO) via post-processing treatment. The crystal quality indicated a relation to power conversion efficiency (PCE); this was combined with a comparable morphology profile. In detail, the optimum DSSC device exhibited average sheet-like thickness and a dye loading amount of 43.11 nm and 4.28 ×10-3 mM/cm-2, respectively. Concurrently, a considerable PCE enhancement of the optimum DSSC device (TiO2@MMO-550°) was attained compared to pristine MMO (0.91%), which could be due to boosted electron transfer efficiency. Of the fabricated devices, DSSC fabricated at 550° exhibited the highest PCE (1.91%), with a 35.6% enhancement compared to that obtained at 450°, as a result of its increased open-circuit voltage (3.29 mA/cm2) and short-circuit current (0.81 V). The proposed work delivers an enhanced efficiency as compared to similar geometries.

Dye-sensitized solar cells with efficiencies exceeding 10% engineered based on La2MnTiO6 double perovskite and MOF-derived Cr2O3/C nanocomposites in bi-layered photoanodes

To improve the photoanode performance of dye-sensitized solar cells (DSSCs), developing double-layered photoanodes have been proposed consisting of La2MnTiO6 + Cr2O3/C nanocomposites in diverse ratios to find the optimal amount. The (x%) La2MnTiO6 + (y%) Cr2O3/C nanocomposites were coated as the overlayer and TiO2 nanoparticles as the underlayer in photoelectrodes. La2MnTiO6, Cr2O3/C, and La2MnTiO6 + Cr2O3/C nanocomposites have been synthesized using sol-gel method, MIL-101(Cr), and hydrothermal method, respectively, and applied as effective light-absorbing photoelectrode layers on the top of TiO2 photoanode in DSSC and compared to TiO2 monolayer film. Numerous analyses and photocurrent density-voltage (J-V) plots were taken to evaluate nanocomposites characteristics. Because of superior light absorbing as well as light-scattering abilities, high amount of dye loading, porous surfaces with high electron transport capacity, and less electron-hole recombination at the 70%La2MnTiO6 + 30%Cr2O3/C film/TiO2/electrolyte interface, the champion cell based on TiO2/20% (70%La2MnTiO6 + 30%Cr2O3/C) photoanode showed a 2.19-fold higher power conversion efficiency (PCE = 9.00%) than the traditional TiO2 monolayer based photoanode (PCE = 4.11%). The amount of the 70%La2MnTiO6 + 30%Cr2O3/C composite loading in the second layer film on the TiO2 layer was also varied in photoanodes. By optimizing the percentage of composite loaded in the second layer, champion device with optimal TiO2/15% (70%La2MnTiO6 + 30%Cr2O3/C) nanocomposite unveiled the largest PCE = 10.07%, enhancing the PCE by about 11.8% and 145% in comparison with TiO2/20% (70%La2MnTiO6 + 30%Cr2O3/C) and monolayer TiO2 photoanodes, respectively.

Efficient Solar Cells Based on Porphyrin and Concerted Companion Dyes Featuring Benzo 12-Crown-4 for Suppressing Charge Recombination and Enhancing Dye Loading.

In recent years, various porphyrin dyes have been designed to develop efficient dye-sensitized solar cells (DSSCs). Based on our previously reported porphyrin dye XW43, which contains a phenothiazine donor with two diethylene glycol (DEG)-derived substituents, we herein report a porphyrin dye XW89 by introducing a benzo 12-crown-4 (BCE) unit onto the N atom of the phenothiazine donor. On this basis, XW90 and XW91 have been synthesized by replacing a DEG chain in XW89 with two DEG chains and a 12-crown-4 unit, respectively. For iodine electrolyte-based DSSCs, dyes XW89-XW91 exhibit VOC values of 765-779 mV, higher than that of XW43 (755 mV), which may be related to the strong capability of the BCE group in binding Li+ and thus suppressing the downward shift of the TiO2 conduction band and interfacial charge recombination. Moreover, the smaller size of 12-crown-4 than the DEG unit enables higher adsorption amounts of the dyes than XW43, contributing to an enhanced JSC value. Due to the presence of two BCE units, dye XW91 exhibits the highest dye loading amount and JSC of 1.86 × 10-7 mol cm-2 and 19.79 mA cm-2, respectively, affording a high PCE of 11.1%. To further enhance the light-harvesting ability, a concerted companion (CC) dye XW92 has been constructed by linking the two subdye units corresponding to the porphyrin dye XW91 and an organic dye. As a result, XW92 affords an enhanced JSC and efficiency. Further coadsorption of XW92 with chenodeoxycholic acid achieved the highest efficiency of 12.1%. This work provides an effective approach for fabricating efficient DSSCs sensitized by porphyrin and CC dyes based on the introduction of crown ether units with smaller sizes and stronger Li+ affinities.

Double Fence Porphyrins Featuring Indacenodithiophene Group as an Effective Donor for High‐Efficiency Dye‐Sensitized Solar Cells (Adv. Energy Mater. 20/2023)

Dye-Sensitized Solar Cells In article number 2300353, Tzu-Chien Wei, Chen-Yu Yeh, and co-workers report new porphyrin dyes for dye-sensitized solar cells. The indacenodithiophene unit is used for improving the light-harvesting ability of dyes, and appropriate alkoxyl chains are chosen to balance dye loading amount and molecular aggregation, and retard the approach of the electrolyte to the surface of TiO2.

Preparation and Photovoltaic Evaluation of CuO@Zn(Al)O-Mixed Metal Oxides for Dye Sensitized Solar Cell.

In this manuscript, a series of dye-sensitized solar cells (DSSCs) were fabricated as a function of post-processing temperature based on mesoporous CuO@Zn(Al)O-mixed metal oxides (MMO) in conjunction with dye N719 as the main light absorber; the proposed CuO@Zn(Al)O geometry was, in turn, attained using Zn/Al-layered double hydroxide (LDH) as a precursor via combination of co-precipitation and hydrothermal techniques. In particular, the dye loading amount onto the deposited mesoporous materials was anticipated via regression equation-based UV-Vis technique analysis, which evidently demonstrated a robust correlation along with the fabricated DSSCs power conversion efficiency. In detail, of the DSSCs assembled, CuO@MMO-550 exhibited short-circuit current (JSC) and open-circuit voltage (VOC) of 3.42 (mA/cm2) and 0.67 (V) which result in significant fill factor and power conversion efficiency of 0.55% and 1.24%, respectively. This could mainly be due to the relatively high surface area of 51.27 (m2/g) which in turn validates considerable dye loading amount of 0.246 (mM/cm-2).

New A3B-type naphthyl Zn(II) porphyrins as DSSC dyes: Effect of anchoring group and co-adsorption for enhanced efficiency

Two new Zn(II) porphyrin dyes ZnNPCA and ZnNPHy bearing three naphthyl groups and one carboxyphenyl/hydroxyphenyl anchoring group in an A3B meso substitution pattern was synthesized utilizing a mixed condensation approach. The redshifted absorption bands to 427 nm as impacts on the extended conjugation with three naphthyl substituents. Similarly, the emission spectrum also exhibits a redshift than ZnTPP-COOH dye. The anodic shift was found in the reduction potential of the naphthyl dyes with the carboxylic acid anchor (ZnNPCA), facilitating the more favourable electron injection. Moreover, the naphthyl porphyrin dyes positively interacted with semiconducting TiO2, whose binding mode was further established using FT-IR. While interacting with titania, the more broadening absorption spectra exhibit strong electronic coupling and will benefit the electron injection. The high dye loading amount obtained for ZnNPCA dye was 13.1 × 10−8 mol cm2, which is more significant towards light harvesting. DSSC devices were fabricated using porphyrin-sensitized photoanodes. ZnNPCA showed better efficiency than ZnNPHy owing to higher dye loading onto the titania surface. Furthermore, the influence of co-adsorbent DCA on the photovoltaic performance of the fabricated DSSC devices was investigated. As a result, a maximum efficiency of 1.85% was achieved for ZnNPCA/DCA device. In addition, electrochemical impedance spectroscopy results revealed a higher electron lifetime (6.14 ms) for this device, supporting better suppression of back reactions.

Enhanced photovoltaic performance of D-π-A organic sensitizers by simple fluorination of acceptor unit

A simple and facile molecular modification method is presented to enhance the photovoltaic and photoelectrochemical properties of D- π -A organic sensitizers. This modification is obtained by incorporating fluorine as an additional acceptor unit. By the electron-withdrawing ability of fluorine, the electron transfer to the anchoring group is promoted, which ultimately leads to a decrease in the HOMO-LUMO energy gap. In addition, the incorporated fluorine also induces prominent J -aggregation, resulting in an increase in the dye loading amount on the photoanode. Because of these positive effects, the additional fluorine acceptor enhances both the photocurrent and photovoltage of dye-sensitized solar cells (DSSCs). In particular, electrochemical impedance study reveals that the electron lifetime in the dye-sensitized photoanode also increases by the incorporation of fluorine in the dye molecules, mostly because of enhanced dye loading. • Simple fluorination leads to enhanced photovoltaic property of organic sensitizer. • Electron-withdrawing ability of fluorine extends light absorption range. • Fluorine also induces prominent J -aggregation, resulting in an increased dye loading. • Fluorine greatly enhances the conversion efficiency of DSSCs by about 29%.

Enhancement in Photovoltaic Performance of Solar Cells by Electrostatic Adsorption of Dyes on ZnO Nanorods.

ZnO nanorods were formed by chemical bath deposition on fluorine–doped tin oxide (FTO) glass and the photovoltaic performance of ZnO-based dye-sensitized solar cells (DSCs) was investigated. A DSC with 8 h-grown ZnO nanorods showed a higher power conversion efficiency (PCE) than devices with 4, 6, and 10 h-grown ones. Further improvement in PCE was achieved in a cell with a silver-ion-deposited ZnO/FTO electrode. By deposition of Ag+ on the surface of the 8 h-grown ZnO nanorods, the dye-loading amount increased by approximately 210%, compared to that of pristine ZnO nanorods, resulting in a 1.8-times higher PCE. A DSC with the pristine ZnO/FTO electrode showed a PCE of 0.629%, while in a device with the silver-ion-deposited ZnO/FTO, the PCE increased to 1.138%. In addition, interfacial resistance at the ZnO/dye/electrolyte was reduced to approximately 170 Ω from 460 Ω for the control cell with the pristine ZnO/FTO. We attributed the higher dye-loading amount in the silver-ion-deposited ZnO/FTO to the electrostatic attraction between the positively charged ZnO and carboxylate anions (–COO−) of the N719 dyes.

In-Depth Thermal, Microstructural and Photoluminescence Analysis of Mesoporous ZnO/ZnAl2O4-MMO: The Effect of Molar Ratio

This manuscript reports a detailed preparation and characterization of mesoporous ZnO/ZnAl2O4 mixed metal oxide (MMO) through a two-step solution procedure utilizing Zn/Al layered double hydroxide (LDH) as starting materials. The influence of the molar ratio was comprehensively explored via a number of characterization techniques. Field emission scanning electron microscopy analysis revealed the occurrence of a sheet-like morphology with thickness of 65 nm at molar ratio (r = 6). Simultaneously, a mesoporous nature of the deposited film was observed through the surface area analysis. A considerable value of surface area was obtained (53.3 m2 g−1) through which a high amount of dye was loaded on the deposited film (3.3 × 10−4); the latter was evaluated via a regression equation in conjunction with the ultraviolet visible light analysis. This in turn led to a robust correlation between the anticipated surface area, pore size, and the estimated dye loading amount. Moreover, the optical and photoluminescence (PL) features were investigated using UV–vis and PL techniques, wherein the near-band emission (was observed at around 380 nm. The proposed work may provide an alternative eco-friendly approach for future visible light photodetector application.

Improvement in photovoltaic efficiency of solar cells with ZnO nanorods and electrophoretically-adsorbed dyes

ZnO nanorods grown on the F-doped tin oxide glass by a chemical bath deposition were sensitized by the electrophoretic technique or the conventional soaking method, and the resulting electrodes were applied to photoanodes of dye-sensitized solar cells (DSSCs). The DSSC with an electrophoretically-sensitized ZnO layer showed an increase in both the short-circuit current (Jsc ) and the open-circuit voltage (Voc ), resulting in a 220% enhancement of photovoltaic performance, when compared to that of the reference cell with a conventionally-sensitized ZnO layer. By applying the electrophoresis to dye adsorption, dye-loading amount was considerably increased, and thereby enhancing the light harvesting efficiency and reducing the interfacial charge recombination between photoinjected electrons and I3 −. This led to the enhancement in Jsc and Voc , compared to those of the reference cell.

ZIF-8 and three-dimensional graphene network assisted DSSCs with high performances

Dye sensitization solar cells (DSSCs) have attracted more and more attention because of the increasing energy demand and their environmental-friendly property. ZIF-8 and three-dimensional graphene network (3DGN) are adopted to modify photoanode to improve the resulting photovoltaic performances. The dye loading amount enhances significantly after adding ZIF-8 because of its large BET area and proper aperture, while the presence of 3DGN booms the fast electron transport ability based on its continuous 3D structure and high conductivity. The adsorption amount of dye molecules reaches 2.26 ​× ​10−7molcm−2, which is 2.6 times higher than that of pure TiO2 photoanode. On the other hand, the improved full factor, decreased dark current and electron impedance spectrum further confirm the function of 3DGN. After optimizing the mass fractions of ZIF-8 and 3DNG, the energy conversion efficiency reaches 8.77%, indicating the synergy between the ingredients and the feasibility of the as-prepared composite photoanode.

Cu-BTC-Assisted DSSCs with Improved Photovoltaic Performances

MOF-based composite material is adopted to modify photoanode, and the obtained large BET area is found meaningful to the dye loading amount, which brings about a high short circuit current and incident photon to current conversion efficiency. Meanwhile, three-dimensional graphene networks (3DGNs) are employed to provide a fast transport channel for photo-induced electrons. The morphology is analyzed by SEM, TEM, XRD and Raman spectrum, and the photovoltaic performances are recorded to reveal the specific functions of MOF and 3DGNs. The synergy between MOF, 3DGNs and TiO2is achieved by adjusting their mass fraction. Moreover, the average size of MOF exerts a significant influence on the resulting properties resulting from the scattering ability to incident light. After corresponding optimizing, the short circuit current, open circuit voltaic, fill factor and energy conversion efficiency reach 20.5[Formula: see text]mAcm[Formula: see text], 680[Formula: see text]mV, 0.619% and 8.63%.

Photocatalysts for H2 Generation from Starburst Triphenylamine/Carbazole Donor-Based Metal-Free Dyes and Porous Anatase TiO2 Cube.

A series of novel triphenylamine/carbazole-based D-D-π-π-A dyes DH1-4 and a mesoporous anatase cubic "microcage" TiO2 material (denoted as MC-TiO2 ) were synthesized and combined to obtain dye-sensitized photocatalysts (denoted as DHn/Pt/MC-TiO2 , n=1-4). These catalysts showed better performances in visible-light-driven H2 evolution from water than DHn/Pt/P25-TiO2 catalysts based on commercial P25-TiO2 bulk semiconductor under similar conditions. Compared with P25-TiO2 particles, the porous MC-TiO2 had a large Brunauer-Emmett-Teller surface area, porosity, and exposed {0 0 1} crystal plane, which greatly contributed to the photocatalytic activity. The optimized DH2/Pt/MC-TiO2 photocatalyst exhibited an attractive H2 production rate (16.28 mmol g-1 h-1 based on catalyst mass), and the optimized DH4/Pt/MC-TiO2 photocatalyst showed good stability [turnover number (TON) of 16 699 in 105 h based on dye number], which represents one of the best performances among all reported visible-light-driven heterogeneous catalytic systems. Compared with the other dyes in this series, the high H2 production rate of DH2 on Pt/MC-TiO2 can be attributed to its size-matching effect and thus high dye loading amount, whereas the high TON and durability of DH4/Pt/MC-TiO2 are probably related to the rapid regeneration kinetics of DH4.

Synthesis of mesoporous TiO2 with colloidal gas aphrons, colloidal liquid aphrons, and colloidal emulsion aphrons for dye-sensitized solar cells

High surface area mesoporous titanium dioxide (TiO2) particles have been prepared by three different kinds of colloidal aphrons: colloidal gas aphrons, colloidal liquid aphrons, and colloidal emulsion aphrons (CEAs). The precipitate of amorphous TiO2 was prepared by hydrolysis, condensation, and polycondensation reaction of the precursor. The reaction took place under the effect of coulombic repulsion and electrostatic layers of multilayer surfactant molecules. TiO2 particles with various sizes were prepared with different molar ratio of titanium ion to surfactants, which were sodium lauryl sulfate (SDS), cetyltrimetyhlammonium bromide, triblock copolymer Pluronic P123, and triblock copolymer Pluronic F127. The synthesized samples were characterized by X-ray diffraction, Brunauer-Emmett-Teller analysis, N2 adsorption/desorption, and transmission electron microscopy. The mesoporous TiO2 prepared by CEAs method showed a high specific surface area of 224 m2/g with the total pore volume of 0.7751 cm3/g by using SDS as the membrane phase surfactant due to electrostatic attraction favors of anionic surfactant. The solar conversion efficiency of the cell made from TiO2 increases with the combination of increased surface area and total pore volume for higher amount of dye wetting and loading.

Dyes Amount and Light Scattering Influence on the Photocurrent Enhancement of Titanium Dioxide Hierarchically Structured Photoanodes for Dye-Sensitized Solar Cells

In this study, we prepared and analyzed the properties of hill-like hierarchically structured titanium dioxide (TiO2) photoanodes for dye-sensitized solar cells (DSSCs). We expected that the presence of appropriately aggregated TiO2 clusters in the photoanode layer would translate to relatively strong light scattering and dye loading, increasing the photovoltaic efficiency. A detailed light-harvesting study was performed by employing polyvinyl alcohol (PVA) polymers of different molecular weights as binders for the aggregation of the TiO2 nanoparticles (P-25 Degussa). Hence, we obtained a series of TiO2 films, presenting a variety of morphologies. Their reflection, as well as absorbance of light by the attached dye, the amount of dye loading, and the performance of the fabricated DSSC devices were investigated. Our optimized device, with a relatively high dye loading and good light harvesting ability, was able to enhance the short-circuit current (Jsc) in the DSSCs by 23%.

Photovoltaic Performance of Dye-Sensitized Solar Cells Containing ZnO Microrods.

At an elevated temperature of 90 °C, a chemical bath deposition using an aqueous solution of Zn(NO3)2·6H2O and (CH2)6N4 resulted in the formation of both nanoflowers and microrods of ZnO on F-doped SnO2 glass with a seed layer. The nanoflowers and microrods were sensitized with dyes for application to the photoelectrodes of dye-sensitized solar cells (DSSCs). By extending the growth time of ZnO, the formation of nanoflowers was reduced and the formation of microrods favored. As the growth time was increased from 4 to 6 and then to 8 h, the open circuit voltage (Voc) values of the DSSCs were increased, whilst the short circuit current (Jsc) values varied only slightly. Changes in the dye-loading amount, dark current, and electrochemical impedance were monitored and they revealed that the increase in Voc was found to be due to a retardation of the charge recombination between photoinjected electrons and I3− ions and resulted from a reduction in the surface area of ZnO microrods. A reduced surface area decreased the dye contents adsorbed on the ZnO microrods, and thereby decreased the light harvesting efficiency (LHE). An increase in the electron collection efficiency attributed to the suppressed charge recombination counteracted the decreased LHE, resulting in comparable Jsc values regardless of the growth time.

Green synthesis of TiO2 nanoparticles using Bixa orellana seed extract and its application for solar cells

Mesoporous anatase TiO2 nanoparticles are the best photoanode materials for high performance DSSC. Chemical and physical methods used for the preparation of TiO2 nanoparticles suffer with environment related issues e.g. use of toxic solvents, hazardous by-products and consumptions of high energy. We have synthesized mesoporous anatase TiO2 nanoparticles from Titanium (IV) butoxide solution using Bixa orellana seed extract and further used it for making DSSC photoanode. The method offers environment friendly, cheaper and efficient DSSC. Structure, morphology, size and porosity of TiO2 nanoparticles were characterized using XRD, SEM, TEM and N2 sorption measurements. The amount of dye loading by TiO2 was obtained using desorption technique which revealed much higher dye loading for the plant seed grown nanoparticles (G-TNP). TNP and G-TNP demonstrated photovoltaic conversion efficiencies 1.03% and 2.97% respectively. This study therefore demonstrates that the synthesized mesoporous anatase TiO2 naoparticles can serve as promising photoanode materials for DSSC applications.

Au/TiO2 nanotube array based multi-hierarchical architecture for highly efficient dye-sensitized solar cells

Control over balanced high light-harvesting and efficient charge transport is of crucial importance for photoelectrochemical applications but still remains great challenge. We develop here single-wall TiO2 nanotube array with in-situ deposited Au nanoparticles. Based on this Au–TiO2 hybrid, we further build a “cigar-like” Au/TiO2-nanotube-array/TiO2-nanoparticles multi-hierarchical architecture through a novel vacuum-assisted colloid-filling approach for dye-sensitized solar cell application. In this elaborate structure, Au nanoparticles welding on nanotube walls play dual roles of direct injecting hot electrons into TiO2 to elevate the conductivity of TiO2 film by about 4 times (under illumination) for fast electron transport, and introducing a plasmonic effect to improve light-harvesting as well. Meanwhile, the thick TiO2 nanoparticulate decoration provides the photoanode vast surface area for ~3.2 times the dye-loading amount of the pristine TiO2 nanotube array based electrode, which will further boost the light-harvesting remarkably. The resulting dye-sensitized solar cell yields an impressively high power conversion efficiency of 8.93%, which is 190.4% that of the pristine TiO2 nanotube array based device. The technology presented in this work provides also a promising prospect for the preparation of multi-hierarchical structures for a wide range of applications, such as photocatalysis and gas sensors.

Pyridyl/hydroxyphenyl versus carboxyphenyl anchoring moieties in Zn - Thienyl porphyrins for dye sensitized solar cells.

For developing efficient DSCs, anchoring moieties need to be understood in detail with respect to a particular dye. Herein, we have synthesized new Zn-thienyl porphyrin dyes based on pyridyl and hydroxyphenyl anchors and compared with traditional carboxyphenyl anchoring group. The effect of such variation in anchoring groups was investigated with UV-vis and fluorescence spectroscopy as well as electrochemical studies. The hydroxyphenyl appended dye showed higher molar extinction coefficient and red shifted emission bands. Both pyridyl and hydroxyphenyl dyes showed adsorption over TiO2 semiconductor. The dye loading amount was found to be greater for carboxyphenyl dye due to stronger bidendate coordination of the carboxy group, as revealed by FT-IR studies. The electrochemical potentials were found to be strongly influenced by the anchoring functionality and all the dyes showed positive driving force for electron injection to the conduction band of TiO2 and regeneration of oxidized dye by the redox electrolyte. DSC devices were fabricated for each of the dyes and characterized well. Hydroxyphenyl dye showed higher Voc as a result of lower back reactions. Transient photovoltage decay measurments indicated lower recombination rate in hydroxyphenyl and pyridyl than the carboxyphenyl anchored thienyl porphyrins offering potential for further dye optimization.

The investigation of novel D-π-A type dyes (MK-3 and MK-4) for visible light driven photochemical hydrogen evolution

Two novel donor-π-acceptor (D-π-A) semiconductor organic dyes have been synthesized for the photochemical hydrogen evolution reaction (HER) to sensitize TiO2 for the first time. The molecular structures of D-π-A semiconductor organic dyes, which are entitled as MK-3 and MK-4, have been characterized by NMR spectroscopy method; and also electrochemical and optical properties have been investigated by cyclic voltammetry and UV–Vis absorption techniques, respectively. Amount of dye loading on TiO2 surface has been investigated by EDX method. The HER activities have been explored in the presence of triethanolamine (TEOA) as a electron donor reagent under sunlight (solar simulator illumination limited by cut-off filter λ ≥ 420 nm) in the absence and presence of co-catalysts (Pt and Cu2WS4). Transient photocurrent densities of MK-3/TiO2 and MK-4/TiO2 electrodes have been reached to 110 μA cm−1 and 275 μA cm−1, respectively. The photocatalytic HER activities have been relatively enhanced in the presence of the Pt or Cu2WS4 co-catalysts (dye/TiO2/Cu2WS4 or dye/TiO2/Pt) when compared to only dye/TiO2. The HER rates have been found as 427, 1277, 675, 682, 1027 and 795 μmolg−1h−1 for the MK-3/TiO2, MK-3/TiO2/Pt, MK-3/TiO2/Cu2WS4, MK-4/TiO2, MK-4/TiO2/Pt and MK-4/TiO2/Cu2WS4, respectively. The differences of photochemical activities of MK-3/TiO2 and MK-4/TiO2 have been stated taking into account dye molecule structures. Moreover, the HER mechanism have been described by using electrochemical band energy levels of dyes, TiO2 and Cu2WS4 co-catalyst.