Photoconversion Efficiency Research Articles

Nitrogen and chlorine co-doped carbon dots to enhance the efficiency of dye-sensitized solar cells

A novel and facile hydrothermal route is reported for preparing the phthalocyanine supported on nitrogen and chlorine doped carbon dots ([email protected]/Cl-CDs) with extraordinary stability in water. Two types of [email protected]/Cl-CDs are synthesized using green carbon, nitrogen, and chlorine sources. Using N/Cl-CDs to support phthalocyanines led to high stability of these phthalocyanines in water. The computational studies of the [email protected]/Cl-CDs suggest their application as sensitizing systems in dye-sensitized solar cells (DSSCs). Following this, the usability of [email protected]/Cl-CDs systems in DSSCs was studied. The obtained data indicated that good photoconversion efficiencies were extracted from the devices containing [email protected]/Cl-CDs. The prepared [email protected]/Cl-CDs showed effective sensitizing ability; it confirmed that N/Cl-CDs can act as an effective co-sensitizer in phthalocyanine-sensitized solar cells (Pc-SSCs). Based on the computational results, adding the N/Cl-CDs is lowering the band gap. For example, in the case of NiPc, the band gap was reduced from 2.22 eV to the 0.014 eV. This phenomenon is causing to easier transfer of electron from valance band to conducting band. In addition, presence of CO2H moieties is causing the lower band gap. Computational studies are revealed that the Ni2+ and Zn2+ do not contribute in the isosurfaces of orbitals. In addition, it was found that the transfer of electron between dyes and CDs could be occurred. In another word, transfer of electron from CDs to the dye can be observed. Based on the partial density of states (PDOSs) results, the contribution of metal ions in orbitals in most of the cases are negligible; although in cases such as NiPc and NiTCPc the metal ion is showing some contributions in HOMO/LUMO orbitals. The results showed that N/Cl-CD is playing an important role on the properties of orbitals such as HOMO and LUMO.

Highly efficient photocatalytic degradation of hazardous organic and inorganic contaminants by heterogeneous nZVI-doped Al2ZnTiO6 double perovskite/g-C3N4 photocatalyst under visible light irradiation

Among the hazardous organic and inorganic pollutants, organic dyes, nitrate (NO3-), carbon dioxide (CO2), and toxic heavy metals (THMs) are four types of hazardous contaminants that have become a serious global problem. Recently, perovskite photocatalysts have shown high efficiency in removing water and air contaminants. In this research, zero-valent iron nanoparticles (nZVI)- doped Al2ZnTiO6 (AZTO) double perovskite/graphitic carbon nitride (g-C3N4(gCN)) nanocomposite (NC) was firstly synthesized by the sol-gel method as a new high-efficiency perovskite photocatalyst. Also, the influence of the main factors such as solution pH, reaction time, photocatalyst dosage, and contaminants concentration on the photocatalytic performance of the nZVI-doped Al2ZnTiO9/g-C3N4 nanocomposite was evaluated. Due to the unique features of the nZVI-doped Al2ZnTiO6/g-C3N4 structure and suitable band gap position, which is suitable for the efficient migration e-/h+ charges dissociation and the enhancement of photocatalytic activity, this nanocomposite showed effective performance to the elimination of methyl orange (MO) anion, and methylene blue (MB) cation dye, NO3-, CO2, and THMs contaminants. The UV–visible spectra showed the elimination efficiency of 88%, 87%, 80%, 72%, and 90% for methyl orange anion dye, methylene blue cation dye, nitrate, carbon dioxide, and toxic heavy metals in optimal experiment conditions, respectively. Also, IEC and GC analysis showed an efficiency of 60% for the photoconversion of nitrate to harmless nitrogen gas (N2) and 42% for the photoconversion efficiency of CO2 to Methane (CH4) gas fuel. Eventually, the nZVI-doped Al2ZnTiO6/g-C3N4 nanocomposite displayed good recyclability and high photocatalytic activity compared to recently synthesized photocatalysts by testing its photocatalytic property after five repetitions.

Design and Synthesis of Novel NIR‐Sensitive Unsymmetrical Squaraine Dyes for Molecular Photovoltaics

Two novel near‐infrared (NIR)‐sensitive unsymmetrical squaraine dyes, SQ‐258 and SQ‐259, for their suitability as a sensitizer in dye‐sensitized solar cells (DSSCs) are designed and synthesized, followed by photophysical and photovoltaic characterizations. It is demonstrated that introducing a 1,3‐indandione acceptor unit in the central squaric acid core of SQ‐259 leads to the suppression of dye aggregation owing to its nonplanar molecular geometry and the broadening of the optical absorption and photon‐harvesting window up to 800 nm. Owing to the extended wavelength photon harvesting, SQ‐259 improves the photoconversion efficiency (PCE) compared to its SQ‐258 dye counterpart. However, despite its wide wavelength photon harvesting, the improvement in the PCE of SQ‐259 is less pronounced, and this is attributed to the small driving force for injection of electrons (0.29 eV), hampered electronic coupling, and decreased electron lifetime for resistance to recombination (7.9 ms), which is confirmed by the cyclic voltammetry, quantum chemical calculation, and electrochemical impedance spectroscopic investigations, respectively.

Controlled crystallization and surface engineering of mixed-halide γ-CsPbI2Br inorganic perovskites via guanidinium iodide additive in air-processed perovskite solar cells

In this report, we demonstrate enlarged grain size (up to ∼3 μm) in ambient-stable black γ-phase CsPbI2Br thin films through the regulated addition of guanidinium iodide (GAI) as an effective volatile additive. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) measurements indicate the complete sublimation of GAI following annealing, with no inclusion inside the final γ-CsPbI2Br perovskite lattice. GAI is found to participate by retarding the cation–anion reaction via the Cs+ and GA+ cation-exchange process. We find that inorganic perovskite solar cells (IPSCs) devices made from (CsPbI2Br)0.925 + 0.075 GAI and a phenyltrimethylammonium chloride (PTACl) passivation retain a solar-friendly band-gap of 1.91 eV and excellent device performance, with the best open-circuit voltage reaching as high as 1.34 V, with highly reproducible and stable photo conversion efficiencies of 16.88% (for 0.09 cm2) and 15.60% (large area 1 cm2) under ambient conditions. Photostability analysis further demonstrated negligible efficiency loss over 1000 h under continuous one-sun equivalent illumination, indicating GAI additive as a promising approach toward ambient stable, all-inorganic high-efficiency solar cells.

PtSe2 outperforms Pt as a counter electrode in dye sensitized solar cells

In the present study, we show that PtSe2 films, prepared by soft selenization of pre-deposited Pt, is a very efficient counter electrode (CE) in dye sensitized solar cells (DSSCs). Devices based on PtSe2 achieve better photoconversion efficiency (9.5 ± 1.2%) than those employing bare Pt CE (9.18 ± 0.21%), even if the latter use three times more Pt loading than that used to prepare the PtSe2 CE. Films with of various Pt loadings have been prepared by electrodeposition and their catalytic properties have been investigated and compared with films of corresponding Pt loading which have been transformed to PtSe2 by low-temperature selenization. The improved performance of the PtSe2 CEs has been assigned to the higher availability of catalytic active sites and the more effective mechanism of interfacial electron transfer. This is a first attempt to explore the role of PtSe2 as the CE in DSSCs. The strong advantages of PtSe2 in relation to catalytic activity, stability, efficiency, combined with cost reduction, due to the lower mass loading required for a given performance, renders this noble-transition metal dichalcogenide a promising candidate to boost the performance of third generation photovoltaics, opening-up possibilities, at the same time, for other applications where Pt is used as the catalyst.

Review on Separation Processes of End-of-Life Silicon Photovoltaic Modules

Solar energy has gained prominence because of the increasing global attention received by renewable energies. This shift can be attributed to advancements and innovations in solar cell technology, which include developments of various photovoltaic materials, such as thin film and tandem solar cells, in addition to silicon-based solar cells. The latter is the most widely commercialized type of solar cell because of its exceptional durability, long-term stability, and high photoconversion efficiency; consequently, the demand for Si solar cells has been consistently increasing. PV modules are designed for an operation lifespan of 25–30 years, which has led to a gradual increase in the number of end-of-life PV modules. The appropriate management of both end-of-life and prematurely failed PV modules is critical for the recovery and separation of valuable and hazardous materials. Effective methods for end-of-life PV waste management are necessary to minimize their environmental impact and facilitate transition to a more sustainable and circular economy. This paper offers a comprehensive overview of the separation processes for silicon PV modules and summarizes the attempts to design easily recyclable modules for sustainable solar module development. Based on the studies summarized in this paper, suggestions are provided for future research.

Metallophtalocyanine Used Interface Engineering for Improving Long‐Term Stability of Methylammonium Lead Triiodide Perovskite

CH3NH3PbI3 perovskite solar cells using metal phthalocyanines (MPcs) with decaphenylcyclopentasilane (DPPS) are fabricated and characterized. The effect of addition of MPcs on the photovoltaic properties is investigated by changing the central element of the MPc and depositing MPc and DPPS successively on the perovskite layer. When silicon phthalocyanine is used to the cell, the microstructure of the perovskite film improves, which results in improvement of the open‐circuit voltage, fill factor, and photoconversion efficiency. For cells with only MPcs as the hole‐transport layer, the conversion efficiency increases by passivation with the phthalocyanine and crystal growth at room temperature.

Laser-induced graphene as a sustainable counter electrode for DSSC enabling flexible self-powered integrated harvesting and storage device for indoor application

Dye-sensitized solar cells (DSSCs) are gaining a newfound interest thanks to their superior ability to harvest indoor light with efficiency higher than other photovoltaic technologies. This study reports, for the first time, the possibility of using laser-induced graphene (LIG) as a flexible counter electrode material for DSSCs. A flexible LIG (F-LIG) electrode was fabricated by direct laser writing of a polyimide film, without the need of a starting conductive substrate. The prepared electrodes showed a higher catalytic activity towards the reduction of I3−/I−with respect to a more expensive Pt-based counter electrode. Moreover, the F-LIG electrodes outperformed electrodeposited PEDOT as a catalytic material for reduction of a copper bipyridyl complex (Cu(II/I)(tmby)2TFSI2/1) electrolyte. The F-LIG based DSSCs showed an open circuit voltage as high as 0.94 V and an increase in photoconversion efficiency higher than 60% with respect to the PEDOT-based counterpart, stepping from 3.08% to 4.96%. Thanks to the easy one-step laser-based fabrication process, the LIG-based DSSC was integrated with a LIG-based supercapacitor (SC), obtaining a flexible energy harvesting and storage system that was able to self-charge both under simulated solar illumination and under indoor artificial illumination, appearing to be a promising energy source for the next generation of self-powered connected Internet of Things devices.

Analysis of Si Back‐Contact for Chalcogenide Perovskite Solar Cells Based on BaZrS3 Using SCAPS‐1D

AbstractBarium zirconium sulfide (BaZrS3), a chalcogenide perovskite, is attracting a lot of attention for thin‐film photovoltaic (PV) application. Unlike the lead halide perovskites, it is stable and does not contain toxic elements. Herein, PV devices incorporating barium zirconium sulfide (BZS) are investigated numerically as a photoabsorber with a back‐contact layer of both crystalline and amorphous p+ type silicon, using a Solar Cell Capacitance Simulator software‐1D. The titanium (Ti) alloyed BZS, which has an electron‐energy bandgap close to optimum for a single junction PV device, is also investigated. A systematic study is carried out by varying the thickness, doping density, and defect density in the BZS layer. Among the two phases of Si, the amorphous one results in higher photoconversion efficiency (PCE) due to a favorable energy band alignment with BZS. The corresponding best PCEs predicted from the study are 19.7% for BZS films and 30% for Ba(Zr0.95Ti0.05)S3 films with the amorphous Si as back‐contact.

Enhanced photo conversion efficiency of Nb2O5/TiO2 bilayer photoanode for Dye-Sensitized Solar Cells

This work is focused to improve the photovoltaic parameters in DSSC by introducing a bilayer photoanode. Nb2O5/TiO2 bilayer photoanodes were prepared by screen printing method. The microstructural, crystalline nature, and morphological properties were analysed. Charge transfer processes in Nb2O5/TiO2 bilayer photoanode and TiO2 photoanode were analysed. The electron behavior in the device was investigated by electrochemical impedance spectroscopy (EIS) measurement. It was inferred that charge transfer resistance significantly lowered in the Nb2O5/TiO2 bilayer photoanode. In addition, the effective electron lifetime was significantly improved, and the recombination rate was reduced. DSSCs devices were fabricated using Nb2O5/TiO2 bilayer and TiO2 unilayers as photoanode, N719 dye, iodide-based electrolytes and platinum counter electrode. Highest efficiency of 5.4% was achieved in the bilayer photoanode system for an optimum thickness of Nb2O5.

2D Ti3C2 MXene interfaced ZnO/WO3 thin film nanostructures towards improved photoelectrochemical water splitting

We explored the morphology evolution approach for sustained photoelectrochemical (PEC) water splitting by developing dual heterojunction. Herein, novel ZnO/WO3/Ti3C2 photoelectrode has been developed for the first time by the integration of flake-like ZnO, nanocrystal featured WO3, and layer-structured two-dimensional (2D) Ti3C2 MXene morphologies towards PEC activity under simulated solar light. By adjusting the radio frequency (RF) magnetron sputtering and post-annealing, flake-like/nanocrystals featured ZnO/WO3 heterostructure observed with uniform growth of WO3 nanocrystals over the flake-like ZnO. Further, efficient integration of layer-structured 2D Ti3C2 MXene on ZnO/WO3 was provided through spin-coating. Utilizing robust surface interface between ZnO, WO3, and Ti3C2, optical transmittance and band gap have been modified. Accordingly, ZnO/WO3/Ti3C2 improved the photocurrent generation about 1.4 × 10−3 A/cm2 compared to pure ZnO (7.8 × 10−4 A/cm2) and ZnO/WO3 (1.1 × 10−3 A/cm2) at +0.4 V. These findings further provided a photoconversion efficiency of 1.16 % by the ZnO/WO3/Ti3C2 at +0.4 V. The PEC studies proved that electrically conductive Ti3C2 MXene can significantly separate the charge carriers from ZnO/WO3. On the other hand, this morphology-induced architecture proved sustainable surface interaction with KOH electrolyte than Na2SO3 and Na2SO4 media. Overall, the above developments suggest a robust interface in ZnO/WO3/Ti3C2 under controlled surface morphology and PEC water splitting activity.

Controlling the electrocatalytic activities of conducting polymer thin films toward suitability as cost-effective counter electrodes of dye-sensitized solar cells

Role dopant anions and solvents in electropolymerized conducting polymers (CPs) on controlling the morphology of thin films and electrocatalytic activities to judge their suitability as low-cost counter electrodes (CE) of dye-sensitized solar cells ( DSSCs) was systematically investigated. Amongst various CPs such as polyaniline (PANI), polypyrrole (PPy), and PEDOT with sodium dodecyl sulfate (SDS) as a dopant, PEDOT was found to exhibit the best photovoltaic performance with a photoconversion efficiency (PCE) of 6.99 %. This was attributed to the best electrocatalytic activity due to the smallest ΔEp, most minor R1, and nano-morphology-assisted high surface area, as confirmed by CV, EIS, and FE-SEM investigations. Using PEDOT as CP, the nature of dopants such as SDS, TFSI, and ClO4 has also been found to control the electrocatalytic activities and the morphology of the fabricated thin films affecting overall photovoltaic performance DSSCs. Amongst the various CP-based CE fabricated using different dopants and solvents, PEDOT:TFSI thin films prepared in acetonitrile solvent and used as CE exhibited not only the best electrocatalytic activity as CE but also demonstrated the best photovoltaic performance with PCE of 7.0 %, which almost similar to that of DSSC utilizing Pt as CE with PCE of 7.1 %. Therefore, it was concluded that the nature of CP and dopant ions were vital factors in governing the electrocatalytic activities of the thin films to ensure their suitability as CE for optimal functioning and controlling the DSSC performance.

Environmentally benign synthesis of TiO2-ZnO nanocomposite for efficient dye-sensitized solar cell

This work presents betanin dye-loaded TiO2-ZnO thin film solar cells for solar energy harvesting. The TiO2-ZnO nanocomposite was prepared by the one-step microwave-assisted technique. Structural studies exhibit mixed phases of rutile and wurtzite structure of TiO2 and ZnO respectively. The morphological investigations of deposited TiO2-ZnO nanocomposite showed interconnected many-fold nanoflakes morphology. EDS confirms the formation of stoichiometric TiO2-ZnO nanocomposite films. An optical study demonstrates electronic transition with a bandgap energy range of 2.72 to 2.94 eV. Photovoltaic performance shows photocurrent from 1.62 to 2.73 mA cm–2 with the photovoltage of 659–795 mV in the range with a 3.25% photo-conversion efficiency for the sample of TZO3 dye-sensitized solar cell (DSSCs).

High Performance Photorechargeable Li‐Ion Batteries Based on Nanoporous Fe2O3 Photocathodes

AbstractIn recent years, photorechargeable Li‐ion batteries (Li‐PRBs) are investigated as potential energy devices to supply continuous power to remote IoT or electronic devices. These Li‐PRBs, due to their lightweight and low‐cost, offers various advantages compared to conventional combination of solar cells and a battery. Single active material‐based PRBs have gained attention due to the use of multifunctional materials which perform both solar energy harvesting and storage, however most of the PRBs studied so far are based on ion intercalation. Herein, the use of conversion type active material α‐Fe2O3 for efficient and stable operation of Li‐PRBs is demonstrated. Cost‐effective solution processing method is used to synthesize α‐Fe2O3 nanorods (NRs), which form nanoporous morphology when blended with Multi‐walled carbon nanotubes / Phenyl‐C61 butyric acid methyl ester (MWCNT/PCBM) conducting additives to form photocathodes. α‐Fe2O3 NRs shown simultaneous solar energy harvesting in visible region of spectra, owing to its energy bandgap Eg ≈ 2.1 eV, and efficient Li‐ion storage via conversion reaction mechanism. Li‐PRB has shown photoconversion and storage efficiency of ≈1.988% when illuminated with blue LED (λex ≈ 470 nm) for large voltage window (0.8–2.57 V). The use of conversion type material like Fe2O3 in PRBs opens up new pathways to explore new materials and mechanisms for these emerging devices.

High efficiency Cu2MnSnS4 thin film solar cells with SnS BSF and CdS ETL layers: A numerical simulation

The quaternary compound copper manganese tin sulfide Cu2MnSnS4 is a potential absorber semiconductor material for fabricating thin film solar cells (TFSC) thanks to their promising optoelectronic parameters. This article numerically investigated the performance of Cu2MnSnS4 (CMTS)-based TFSC without and with tin sulphide (SnS) back surface field (BSF) thin-film layer. First, the impact of several major influential parameters such as the active material's thickness, doping concentration of photoactive materials, density of bulk and interface defect, working temperature, and metal contact, were studied systematically without a BSF layer. Thereafter, the photovoltaic performance of the optimized pristine cell was further investigated with an SnS as BSF inserted between the absorber (CMTS) with a Platinum back metal of an optimized heterostructure of Cu/ZnO:Al/i-ZnO/n-CdS/p-Cu2MnSnS4/Pt. Thus, the photoconversion efficiency (PCE) of 25.43% with a JSC of 34.41 mA/cm2 and VOC of 0.883 V was achieved under AM1.5G solar spectrum without SnS BSF layer. Furthermore, an improved PCE of 31.4% with a JSC of 36.21 mA/cm2 and VOC of 1.07 V was achieved with a quantum efficiency of over 85% in the wavelengths of 450–1000 nm by the addition of SnS BSF layer. Thus, this obtained systematic and consistent outcomes reveal immense potential of CMTS with SnS as absorber and BSF, respectively and provide imperious guidance for fabricating highly a massive potential efficient solar cell.

PbSe nanorod-quantum dot bulk nano-heterojunction solar cells generating multiple excitons with record photo conversion efficiencies

Multi-exciton-generation (MEG) process is critical due to its potential to push solar cell photoconversion efficiencies (PCEs) beyond theoretical limits. However, cells with this feature are rare, as the demonstration of this characteristic property in a working cell is challenging. Herein, a donor-acceptor type bulk nano-heterojunction layer, prepared by blending two nanostructures known to have high MEG yields, i.e., PbSe quantum dot-QDs and PbSe nanorods-NRs, is utilized as the light absorbing active layer. Transmission electron microscopy images show that NR-donors are surrounded by QD-acceptors, indicating the formation of optimal donor-acceptor interfaces that allow efficient dissociation of photo-generated excitons. Effective charge separation across the NR/QD interface is also demonstrated with valence and conduction band offsets measured in the range of 0.20–0.25 eV. It is found that the type of the hole transport layer has a profound effect in reducing the electron back injection and increasing the MEG efficiency/yield. Cells with 0.97 eV NR-donor band gap exhibit a PCE of 4.09% with a peak internal quantum efficiency greater than 100%. Cells, outperforming the previously reported MEG-based cells comprising PbSe QDs or NRs, demonstrate a staircase-like response in external quantum efficiency, which is considered as the most obvious indicator of an ideal MEG system.

Assessment of Photosynthetic Carbon Capture versus Carbon Footprint of an Industrial Microalgal Process

It is often read that industrial microalgal biotechnology could contribute to carbon capture through photosynthesis. While technically accurate, this claim is rarely supported by sound figures nor put in regard to the carbon emissions associated with said processes. In this view, this work provides a quantitative assessment of the extent microalgal processes compensation for their carbon dioxide emissions. To do so, microalgae were cultivated under photolimited conditions. Their growth dynamic and photosynthetic apparatus status were monitored by daily cell density measurement and fluorescence assays. Ultimate analyses were used to determine microalgal carbon content. Simultaneously, the power consumption of the process was recorded, and the associated carbon dioxide emissions were computed using European electrical production carbon intensity. All in all, the recorded values confirmed microalgae growth under good physiological conditions and allowed computing the carbon capture rate, the energy storing rate, and the carbon dioxide emissions of the process. The process captured 0.72 ± 0.19 gCO2/day while emitting 182 gCO2/day, on average (over 15 days). The photoconversion efficiency was 4.34 ± 0.68%. Even if it were highly optimized (red/blue LED instead of white, for example), the process could only capture 1.02 ± 0.40% of its emissions. From these figures, the claim stating that a biotechnological microalgal production process could partly compensate for its emission seems rather bold. Authors should, therefore, emphasize other ecosystemic benefits of microalgal cultivation, such as phosphorous intake. Finally, we were also able to evaluate Chlorella vulgaris light and dark respiration (0.0377 ± 0.042 day−1 and 7.42 × 10−3 ± 3.33 × 10−3 day−1), which could help to assess carbon emission by biomass respiratory activity.

Review of Luminescence-Based Light Spectrum Modifications Methods and Materials for Photovoltaics Applications.

The dynamic development of photovoltaic and photo-sensitive electronic devices is constantly stimulated by material and technological advances. One of the key concepts that is highly recommended for the enhancement of these device parameters is the modification of the insulation spectrum. Practical implementation of this idea, although difficult, may be highly beneficial for photoconversion efficiency, photosensitivity range extension, and their cost reduction. The article presents a wide range of practical experiments leading to the manufacturing of functional photoconverting layers, dedicated to low-cost and wide-scale deposition methods. Various active agents, based on different luminescence effects as well as the possible organic carrier matrixes, substrate preparation and treatment procedures, are presented. New innovative materials, based on their quantum effects, are examined. The obtained results are discussed in terms of the application in new generation photovoltaics and other optoelectronic elements.

Green solvent exfoliation of few layers 2D-MoS2 nanosheets for efficient energy harvesting and storage application

In this study, a facile, cost-effective, and green solvent exfoliation route with bio extract was derived from Cissus quadrangularis (MP) and it was used to exfoliate to get the few layers of MoS2. Compared to conventional chemical exfoliation, the green solvent exfoliation method showed quick delamination from the bulk MoS2. To compare the effectiveness of the exfoliation in green solvents, the exfoliation analysis of the bulk MoS2 was conducted in N-Methyl-2-pyrrolidone and another bio-extract with low Hansen properties was derived from Mussa acuminate. The MP-derived green extract showed excellent delamination of the few layers of MoS2 nanosheets with a minimal processing time of 2 h. It was confirmed that the layered structure with a lateral size of 150 nm and a d-spacing was 0.63 nm by HRTEM, and also Raman spectrum revealed the minimum frequency difference (24.6 cm−1) for MP, which confirmed the presence of the few-layer MoS2. The obtained few-layered MoS2 nanosheets were further examined as an electrode material for dye-sensitized solar cells (DSSC) and supercapacitor applications. The fabricated DSSC with MP-electrode showed increased Voc with a photo conversion efficiency (PCE) of 5.14 %. As a supercapacitor electrode, it exhibited a significant potential window expansion of 0.1 V with a specific capacitance of 183 F/g at a scan rate of 5 mVs−1. This work opens up a simple, inexpensive, and eco-friendly green solvent exfoliation methodology to obtain the layers of 2D materials.

Exploiting the complete efficacy of 3D-nitrogen-doped ZnO nanowires photoanode via type-II ZnS core-shell formation toward highly stable photoelectrochemical water splitting

The hierarchical 3D-zinc oxide (ZnO) nanowires (NWs) photoanode promises high cost-to-efficiency ratios toward photoelectrochemical (PEC) water splitting owing to their enthralling characteristics. However, minimal visible light harvesting, and sluggish surface oxidation kinetics severely hinder the water-splitting efficiencies along with the resistance to photo-corrosion. We report a unique strategy of constructing type-II heterostructure of N-doped ZnO NWs with ultrathin zinc sulfide (ZnS) layer to form a core-shell structure that provides dual benefits of accelerating the charge transfer process and significantly enhancing the resistance to photo-corrosion of N-doped ZnO NWs. The PEC water splitting analyses showed that the optimal ZnS/N:ZnO core-shell NWs photoanode exhibited a photocurrent density of 0.85 mA cm−2 at 1.23 Vs RHE which was 3-fold higher than N:ZnO NWs photoanode. The ZnS shell encapsulation effectively protects the N:ZnO NWs core over a period of ∼16 h from detrimental photo-corrosion with 76% photocurrent density retention. Additionally, the integration of multilateral tactics of staggered heterojunction and core-shell formation provided higher photoconversion efficiencies over N:ZnO NWs. The reported approach may provide an alternative to address the sluggish surface kinetics that bothers the chemical stability, prolong the charge lifetime, and thus open up wide opportunities in the construction of efficient and highly stable PEC water-splitting devices.