Nanocomposite Photoanode Research Articles

Barium titanate nanorods/nanoparticles embedded reduced graphene oxide nanocomposite photoanode for dye-sensitized solar cell

Perovskite barium titanate nanorods/nanoparticles (BaTiO3 NRs/NPs) and reduced graphene oxide loaded barium titanate nanocomposite (BaTiO3 NRs/NPs-rGO NC) were synthesized by hydrothermal method and applied as photoanode materials in dye-sensitized solar cell (DSSC). The prepared perovskite nanomaterials were characterized by SEM, HRTEM, EDAX, XRD, XPS, PL and Raman techniques. The photovoltaic performance of DSSC fabricated using BaTiO3 NRs/NPs-rGO NC photoanode delivered a highest PCE of 5.92 %, which was almost twofold higher than the PCE of BaTiO3 NRs/NPs photoanode based DSSC (3.07 %). This improved photovoltaic performance could be attributed to superior light-harvesting and charge transportation behaviour of BaTiO3 NRs/NPs-rGO NC photoanode.

Fabrication of ternary zinc-nickel-copper oxide microsphere nanocomposite photoanode material for boosting dye-sensitized solar cell efficiency

The present study focuses on the development of cost-effective and efficient energy conversion material for fossil-fuel free society. In this context, ternary ZnO-NiO-CuO nanocomposite (NC) prepared using a facile chemical co-precipitation method was used as a photoanode material in dye-sensitized solar cell (DSSC). Concurrently, ZnO nanoparticles (NPs), binary ZnO-NiO and ZnO-CuO NCs were also prepared, characterized and employed as photoanode materials in DSSC. XRD diffraction analysis disclosed successful formation of nanomaterials with relevant structural parameters. SEM investigation displayed spherical and microsphere morphology of ternary ZnO-NiO-CuO NC. EDAX examination confirmed its purity. TEM and HRTEM analysis revealed that the morphology of ternary ZnO-NiO-CuO NC exhibits microspheres with porous nature, whose size ranges from 150 nm to 400 nm. Less intense PL peaks suggested anticipation of relatively low charge recombination, better charge separation and fast electron transport in ternary ZnO-NiO-CuO NC photoanode based DSSC. Consequently, photovoltaic behavior of DSSC integrated with ternary ZnO-NiO-CuO NC photoanode exhibited significantly higher PCE (η) of 4.96 % when compared to DSSC fabricated using pristine ZnO NPs (2.48 %), ZnO-NiO (3.18 %) and ZnO-CuO NC (4.35 %) photoanodes.

Investigating the effect of ZrO2 nanofibers in ZnO-based photoanodes to increase dye-sensitized solar cells (DSSC) efficiency: Inspecting the porosity and charge transfer properties in ZnO/ZrO2 nanocomposite photoanode

This study is aimed to improve the performance of zinc oxide (ZnO) photoanodes in dye-sensitized solar cells (DSSCs) by exploiting the superior charge transport properties in electro-spun zirconium dioxide (ZrO2) nanofibers in ZnO/ZrO2 nanocomposite photoanodes. The fabricated photoanodes were analyzed by a variety of analyses. The XRD results show that photoanodes are a mixture of two different phases of ZnO and ZrO2 without any additional impurity phase. FESEM images and BET analysis show changes in porosity and effective surface area in the synthesized photoanodes. UV–Vis analysis confirms this conclusion by measuring adsorbed dye molecules on the photoanode surface. In addition, using the photoanodes, DSSCs are prepared for which J-V characterization results show an increase in efficiency from 1.68 to 3.31 %. The addition of ZrO2 nanofiber to the ZnO network increases the porosity and effective surface area and makes it possible to control the dye-loading as well as electrolyte species transport. Furthermore, the results of EIS analysis show that the charge transport in the ZnO/ZrO2 network is carried out more efficiently compared to the bare ZnO photoanode. Although, increasing ZrO2 nanofibers to a certain level can help improve the efficiency, it tends to reduce the efficiency with ZrO2/ZnO ratios of over 10 %.

Nanostructured g-C3N4-decorated TiO2 for superior photoanode performance in dye-sensitized solar cells

This article explores the potential of a novel photoanode material, g-C3N4 doped TiO2 in improving the photon-to-current conversion efficiency of standard dye-sensitized solar cells. The hybrid nanocomposite photoanode shows a higher light conversion efficiency compared to traditional sintered anatase TiO2 (T400). A novel solvothermal method is used to synthesize and assess the performance of the g-C3N4 doped TiO2 as a photoanode for electron collection in dye-sensitized solar cells (DSSC). The results indicate an optimal efficiency of 9% for the fabricated DSSC with g–C3N4/TiO2 (g-TO) nanocomposite photoanode, surpassing the efficiency of DSSCs with TiO2 (T400) as a photoanode. The research presented here highlights that g-C3N4/TiO2 exhibits outstanding properties and holds great potential for implementation in photo energy conversion devices for practical applications.

Structural, optical and photovoltaic properties of V2O5/ZnO and reduced graphene oxide (rGO)-V2O5/ZnO nanocomposite photoanodes for dye-sensitized solar cells

Structural, optical and photovoltaic properties of V2O5/ZnO and reduced graphene oxide (rGO)-V2O5/ZnO nanocomposite photoanodes for dye-sensitized solar cells

Barium titanate perovskite nanoparticles integrated reduced graphene oxide nanocomposite photoanode for high performance dye-sensitized solar cell

Nanocomposites comprised of barium titanate perovskite nanoparticles decorated reduced graphene oxide (BaTiO3-RGO NC) were formed through facile hydrothermal method. X-ray diffractometer profile confirmed crystallite and tetragonal phase of BaTiO3. Identification of D and G bands in Raman investigation and XPS spectra disclosed existence of graphene in the prepared BaTiO3-RGO NC. FE-SEM examination indicates small sized BaTiO3 NPs are obviously decorated on the graphene sheets by strong binding forces between graphene and BaTiO3 NPs. Among graphene of different wt%, BaTiO3-RGO NC with 1.5 wt% showed lowest PL intensity, indicating effective reduction of photogenerated charge carrier recombination. Dye-sensitized solar cell fabricated using BaTiO3-RGO NC photoanode having 1.5 wt% graphene displays high efficiency of 4.93% associated with high photocurrent density.

Li sensitized CdS/TiO2 nanocomposite photoanode for solar water splitting, hydrogen generation and photoelectrochemical (PEC) performance

Li–CdS/TiO2 nanocomposite with different composition 10Li–CdS/TiO2, 20Li–CdS/TiO2, 30Li–CdS/TiO2, 40Li–CdS/TiO2, 50Li–CdS/TiO2 were coated on FTO surface by using doctor blade followed by successive ionic layer adsorption and reaction (SILAR) method. As synthesized Li–CdS/TiO2 photoanode is characterized with field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (UV-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). FE-SEM analysis suggests that, Li–CdS/TiO2 film is 10.2 μm thick, porous, spongy and uniformly covered on FTO surface. The HR-TEM images reveal that the CdS nanoparticles are in intimate contact with the TiO2 nanocrystal shells with the CdS/TiO2 interfaces and the particle size of CdS and Li2S lies in the range of 20 nm–50 nm. UV-DRS analysis shows that, as the loading of Li in CdS/TiO2 films increases, there is decrease in band gap energy. The XPS analysis supports the presence of Li+ in Li–CdS/TiO2 nanocomposite. The PL spectra suggest that, with the increase in extend of Li+ ions into Li–CdS/TiO2, intensity of green emission band increases and it is shifted to higher wavelength. This reflects the low recombination rate of photo generated charge carrier in Li–CdS/TiO2 which is responsible for higher photocatalytic H2 production. The visible light photoanodic performance of Li–CdS/TiO2 was investigated for H2 evolution using aqueous Na2SO3 and Na2S solution under natural sunlight. Among the all-synthesized nanocomposite material, the highest amount of hydrogen produced over 20Li–CdS/TiO2 was found to be 38.61 ml/g/h in natural sunlight. Photoelectrochemical (PEC) performance of Li–CdS/TiO2 was examined. A possible mechanism for photocatalytic hydrogen generation is also discussed.

Tuning the Properties of Reduced Graphene Oxide-Sr0.7Sm0.3Fe0.4Co0.6O3 Nanocomposites as Potential Photoanodes for Dye-Sensitized Solar Cells

The generation of electricity using solar energy is an effective system to overcome the current global energy crisis. In this regard, developing new semiconductor materials can be of great interest in overcoming the challenge of charge carrier recombination and, hence, improving the power conversion efficiency (PCE) in photovoltaic devices, particularly dye-sensitized solar cells (DSSCs). Here, reduced graphene oxide-Sr0.7Sm0.3Fe0.6Co0.4O3 (RGO-SSFC) nanocomposites were synthesized using the hydrothermal method and characterized with the aid of microscopic and spectroscopic techniques, as well as a vibrating sample magnetometer, and further tested for application as photoanodes in DSSCs. Scanning electron microscopy revealed the presence of RGO nanosheets that were fully decorated by irregular- and spherical-shaped SSFC nanoparticles. Fourier-transform infrared spectroscopy confirmed the strong synergistic interaction of the RGO-SSFC nanocomposites. The large surface area of RGO-SSFC nanocomposite photoanodes facilitated effective dye loading, high photon absorption, and efficient electron transfer, resulting in better device performance. Compared to RGO-SSFC-0.1 and RGO-SSFC-1.0, the RGO-SSFC-0.5 nanocomposite showed an enhanced open-circuit voltage (Voc) of 0.84 V, short-circuit current density (Jsc) of 14.02 mA cm−2 , and a PCE of 7.25%. Eosin B and MK-2 organic dyes used as photosensitizers coated on the RGO-SSFC semiconductors resulted in low-cost DSSC photoanodes.Graphical

Preparation and Characterization of ZnO NWs/Graphene Nanocomposite as an Effective Photoanode Electrode for Improving the Performance of the Dye-Sensitized Solar Cells

In the present study, DSSCs were fabricated using pure ZnO NWs and ZnO NWs/Graphene nanocomposite as photoelectrodes. Graphene was incorporated into pure ZnO NWs through a cost-effective Hydrothermal Process to act as an electrical charge carrier. J-V curve of prepared nanocomposite was recorded with a light intensity of 100 mW.cm-2. The created nanocomposites were thoroughly investigated by using different electrical and structural characterization techniques such as SEM, XRD, and J-V characteristics. According to SEM examination, the ZnO NWs/graphene composite-based electrode has more porosity than the electrode made using pure ZnO NWs, which will increase the surface area and the amount of dye that can be absorbed. From the graphene advantages the reduced internal resistance and electron recombination loss, these properties allow electrons to transfer to the collection electrode efficiently. Based on these benefits, the ZnO NWs/Graphene nanocomposite photoanode with thickness of 965.11 nm that was used in the DSSC2 was demonstrated a Jsc of 19.50 mA.cm-2 and conversion efficiency of 9.829053%, which opposite to the result of the DSSC1 without graphene. These results can be encouraged for future improved optoelectronic devices.

Thermoelectric voltage triggered self-biased photoelectrochemical water splitting utilizing visible light active Ag/NaNbO3 nanocomposite photoanode

Nanostructure semiconductor photoactive materials are often used as working photoelectrodes to absorb solar light in conventional photoelectrochemical (PEC) cells for water splitting to demonstrate enhanced PEC performance. However, an external bias is required to start PEC water splitting reactions for the generation of hydrogen. Here, we demonstrate a novel way of designing a self-biased hybrid system that combines a darkened thermoelectric device (TE) and a photoelectrochemical cell with a visible light-active n-type Ag/NaNbO3 photoanode to produce hydrogen via water splitting by utilizing the entire solar spectrum. This method can combine utilization of a visible light photon energy from the Ag/NaNbO3 photoanode with thermal energy from the darkened TE device to overcome the overpotential requirements. Upon light illumination, the photoactive behaviour of the Ag/NaNbO3 photoanode and the voltage generated from the darkened TE device in our hybrid system modifies the band positions of an Ag/NaNbO3 photoanode and spontaneously provide the external overpotential requirement for the PEC process and enhances the H2 production. Compared to the stand-alone PEC device, the TE-coupled PEC hybrid system exhibited ∼17 times enhancement in the photocurrent density and H2 production at zero bias. The electrochemical impedance spectroscopy analysis also shows that the charge transfer process gets significantly enhanced in the hybrid PEC system compared to the PEC cell alone. This finding indicates the synergistic coupling between TE and PEC cells, where a single light energy source can increase H2 production in the hybrid systems without needing an external bias.

Expression of Concern: Solid-state dye-sensitized solar cells based on Zn1-xSnxO nanocomposite photoanodes.

Expression of Concern for 'Solid-state dye-sensitized solar cells based on Zn1-xSnxO nanocomposite photoanodes' by Ayat Nasr El-Shazly et al., RSC Adv., 2018,8, 24059-24067, DOI: https://doi.org/10.1039/c8ra02852d.

Efficient Ti3C2Tx MXene/TiO2 Hybrid Photoanodes for Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) remain a promising technology for clean energy conversion due to their low cost, simple manufacturing, and high scalability. However, to keep these devices competitive against other photovoltaics like organic (OSCs) and perovskite solar cells (PSCs), it is necessary to enhance their efficiency. These improvements can be achieved by optimizing the charge transport and non-radiative carrier recombination within the operating device. Here, we show the design, fabrication, and subsequent characterization of Ti3C2Tx MXene/TiO2 nanocomposite hybrid photoanodes, supported by computational modeling. Ti3C2Tx MXene/TiO2 hybrid photoanodes containing 0.050, 0.075, and 0.100 wt % two-dimensional (2D) Ti3C2Tx flakes were prepared and investigated. The power conversion efficiency (PCE) of the device is found to be enhanced by 20% when only 0.075 wt % Ti3C2Tx was added to TiO2 due to the increase of electron transport in the photoanode. The density functional theory (DFT) calculations of the MXene–TiO2 interface indicate that the anatase potential is lowered, thus increasing the energy difference between the conduction bands of the N719 dye and the nanocomposite and favoring the migration of electrons toward the output terminal. Moreover, DFT results suggest a better separation of the photocarriers at the nanocomposite–N719 interface, which is supported by the measurement of longer electron lifetimes in the photoanode. These features demonstrate that the introduction of Ti3C2Tx into the photoanode is relevant to promote the energy-to-current conversion of DSCCs. Future approaches shall focus on the implementation of different 2D MXene structures to further improve the performance of these class of materials for direct applications in photovoltaic devices and photochemistry.

A TiO2@MWCNTs nanocomposite photoanode for solar-driven water splitting.

A TiO2@MWCNTs (multi-wall carbon nanotubes) nanocomposite photoanode is prepared for photoelectrochemical water splitting in this study. The physical and photoelectrochemical properties of the photoanode are characterized using field emission-scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and linear sweep voltammetry. The results show that the TiO2@MWCNTs nanocomposite has an optical bandgap of 2.5 eV, which is a significant improvement in visible-light absorption capability compared to TiO2 (3.14 eV). The cyclic voltammograms show that incorporating TiO2 with the MWCNTs leads to a decrease in the electrical double layer, thereby facilitating the electron transfer rate in the TiO2@MWCNTs electrode. Moreover, the current density of the photoelectrochemical electrode formed by TiO2@MWCNTs under solar irradiation is significantly higher than that prepared by TiO2 (vs Ag/AgCl). The low charge capacity of the TiO2@MWCNTs electrode-electrolyte interface hinders the recombination of the photogenerated electrons and holes, which contributes to the enhancement of the solar-to-hydrogen (STH) conversion efficiency. The average STH conversion efficiency of the TiO2@MWCNTs electrode under solar exposure from 6 AM to 5 PM is 11.1%, 8.88 times higher than that of a TiO2 electrode. The findings suggested TiO2@MWCNTs is a feasible nanomaterial to fabricate the photoanode using photoelectrochemical water splitting under solar irradiation.

Fabrication of TiO2-ZnO nanocomposite photoanodes to enhance the dye-sensitized solar cell efficiency

Fabrication of TiO2-ZnO nanocomposite photoanodes to enhance the dye-sensitized solar cell efficiency

Investigations of Zr/TiO2-based nanocomposites for efficient plasmonic dye-sensitized solar cells

Renewable energy resources have a wide range of materials to fulfill the energy demand. All developed countries are trying to adopt renewable energy resources to overcome the energy crises. Recent research showed that dye-sensitized solar cells (DSSCs) are optimistic and cheap customers for energy purposes. Most used materials in DSSCs are environment-friendly. Zirconium/titanium dioxide-based nanocomposite photoanodes are mostly stable and efficient for DSSCs. SEM, XRD, UV-visible spectroscopy and Raman spectroscopy were employed to check the morphological, structural and optical properties of Cu and Ag-doped Zr/TiO2, respectively. IV measurements investigation showed that due to the Cu and Ag contents’ effects, the power regeneration efficiency was enhanced by 8.18% by using [Formula: see text] of 0.73 V, [Formula: see text] of 8.78 mA cm[Formula: see text], FF 59.03% and IPCE of 62.43%, due to a shortage in recombinations of charge carrier. The carrier transporting mechanism (EIS) was done at a frequency range of 100 mHz to 1 MHz.

Perovskite zinc titanate-reduced graphene oxide nanocomposite photoanode for improved photovoltaic performance in dye-sensitized solar cell

The current generation of solar cells are playing a predominant role in energy storage industries due to their economic cost, abundant, and compact design for photovoltaic applications. In this context, composite materials based on perovskite zinc titanate nanoparticles (ZnTiO3 NPs) and perovskite zinc titanate-reduced graphene oxide nanocomposite (RGO-ZnTiO3 NC) were prepared by a simple sol-gel technique. The ZnTiO3 NPs and RGO-ZnTiO3 NC were subjected to X-ray diffraction analysis for calculating crystal structure, crystallite size, microstrain, and dislocation density. The band gap energy of the ZnTiO3 NPs and RGO-ZnTiO3 NCs was found to be 2.9 and 3.1 eV, respectively. X-ray photoelectron spectroscopy was used to determine elemental species of the RGO-ZnTiO3 NC. The photovoltaic performance of the dye-sensitized solar cell (DSSC) with RGO-ZnTiO3 NC photoanode exhibited strong dye adsorption to facilitate considerable light absorption and efficient electron transport, due to less surface trapping sites compared to unmodified ZnTiO3NPs photoanode based DSSC. The RGO-ZnTiO3 NC photoanode demonstrated best photovoltaic performance with a short-circuit current density of 4.27 mA cm−2 and better photoelectric conversion efficiency of 1.11%, which is ∼2.6 folds higher than the DSSC with ZnTiO3 NPs photoanode.

Spinel-type ferrites decorated ZnO for enhanced photoelectrochemical water splitting

Among numerous semiconductor photoanodes, ZnO has been widely touted for its high electron mobility in the realm of Photoelectrochemical water splitting. However, some inevitable problems have limited its widening applications, such as narrow light photoresponse range and many surface defects. To this end, we first time demonstrate a novel strategy for CoFe2O4/ZnO and NiFe2O4/ZnO photoanodes by uncomplicated and inexpensive spin-coating and calcination stratagem. The optimal nanocomposite photoanodes showed excellent photocurrent density (2.3 folds higher than bare ZnO photoanode) and a negatively shifted onset potential of 75 mV. Moreover, due to the construction of Type-II heterojunction, the surface trap state of ZnO is reduced, the separation of photoproduced carriers is enhanced, the active sites are increased, and the interface reaction dynamics are accelerated.

Structural effect of Low-dimensional carbon nanostructures on Long-term stability of dye sensitized solar cells

A major challenge in upscaling and commercializing dye-sensitized solar cells (DSSC) is to simultaneously rely on a robust photoconversion efficiency (PCE) along with long-term device stability. Two-dimensional (2D) nanocarbon materials are known to improve the PCE and stability of devices made of hybrid nanocomposite photoanodes. However, there is inadequate knowledge on how the morphology of 2D nanocarbon materials plays an important role in improving photovoltaic (PV) performance and stability. Here we report the comparative effect on the PV performance and the long-term stability of DSSCs made of optimal loadings of few-layer graphene (FLG) flakes and graphene nanoribbons (GNR) into the mesoporous TiO2 active layer. DSSCs were fabricated by using standard nanocrystalline TiO2, GNR-TiO2 and FLG-TiO2 hybrid mesoporous films as anodes and subjected to continuous visible light irradiation to monitor their long-term stability. Results show that the optimized incorporation of GNR (0.005 wt%) and FLG (0.010 wt%) in the mesoporous TiO2 active layer enhances the PCE by 34% and 21% compared to pristine TiO2, respectively. Moreover, the operational stability of hybrid devices shows a 51.6% (for GNR-TiO2) and a 10% (for FLG-TiO2) sustained higher PCE than the device based on bare TiO2, after 273 h of continuous one sunlight soaking. The electrochemical impedance spectroscopy (EIS) and transient photovoltage decay were studied to investigate how GNR strikingly reduces degradation of device performance as compared to its counterpart FLG-TiO2 and TiO2 based cells. This significant enhancement can be attributed to the structural modifications induced by GNR within the TiO2 photoanode, which improves the electron lifetime and reduces non-radiative carrier recombination.

Plasmonic Ag nanoparticles anchored ethylenediamine modified TiO2 nanowires@graphene oxide composites for dye-sensitized solar cell

Proficient photoanode is always vital for obtaining high efficiency in dye-sensitized solar cell (DSSC). Herein, ethylenediamine functionalized TiO2 nanowires graphene oxide (TiO2 NW-NH2/GO) has been synthesized and incorporated with Ag nanoparticles. The prepared plasmonic nanocomposites are characterized by various techniques, such as, diffused reflectance, Raman and X-ray photoelectron spectroscopies, X-ray diffraction, and Scanning/transmission electron microscopies (SEM and TEM). The amine functionalized TiO2 NW-NH2/GO/Ag plasmonic nanocomposites exhibit strong light harvesting and better dye loading, leading to high efficiency. The DSSC integrated with TiO2 NW-NH2/GO/Ag nanocomposite photoanode exhibits remarkable photovoltaic performance (short-circuit current density (Jsc) of 15.09 mA cm−2 and an overall power conversion efficiency (ɳ) of 8.76%) which is double that of the DSSC with pure TiO2 NW photoanodes (4.05%). The enhancement of efficiency, mainly due to the increased current density, is attributed to the improved electron transfer at the photoanode/electrolyte interface. Ethylenediamine gives binding interaction between TiO2 and GO/Ag.

In-situ grown nanoscale p-n heterojuction of Cu2S-TiO2 thin film for efficient photoelectrocatalytic H2 evolution

Nanoscale heterojuction thin film of Cu2S-TiO2 has been grown by sol-gel technique and has been employed for efficient H2 production through water splitting. This nanoscale heterojunction has been grown in three steps which include ion conducting Li4Ti5O12 thin film deposition and ion-exchange (Li+↔Cu+) followed by a sulfurization process. To study the photoelectrochemical performance of this Cu2S-TiO2 heterojunction thin film, photoanodes were fabricated on TiO2 coated FTO substrate. The TiO2 film was deposited by two different methods - the sol-gel method and colloidal TiO2 nanoparticles (TiO2NP). Highest photocurrent of ∼36 mAcm−2 was obtained by Cu2S-TiO2/TiO2NP/FTO photoanode under 0.5 V potential (E Vs. RHE, 1 M KOH). The photocurrent is ∼103 times higher compared to that of the bare TiO2 photoanode and stable for several hours. The photoelectrochemical (PEC) behavior is much higher with respect to previous reports on Cu2S (NP)-TiO2 nanocomposite photoanodes, which is due to the significant reduction in carrier recombination at the electronically coupled Cu2S-TiO2 heterojunction interface.