Electrocatalyst For Dye-sensitized Solar Cells Research Articles

Synthesis of nitrogen-doped carbon dot/ tin disulfide nanosheet composite electro-catalysts for dye-sensitized solar cells.

Nitrogen-doped carbon dots (N-CDs) and vertically-grown tin disulfide (SnS2) nanosheets are synthesized via hydrothermal method and chemical vapor deposition (CVD) technique, respectively. The SnS2 nanosheets are directly fabricated on flexible carbon cloth (CC), and then their basal planes are decorated with N-CDs. The as-prepared composite electrodes are used as the counter electrode for the application in dye-sensitized solar cells (DSSCs). The characterizations of N-CDs and SnS2 nanosheets are studied by high resolution transmission electron microscopy (HR-TEM), scanning electron microscopic (SEM), energy dispersive X-ray spectrometer (EDS), Raman spectrometer and X-ray photoelectron spectroscopy (XPS) ect. Moreover, the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and photocurrent-density voltage (J-V) are utilized to understand the electro-catalytic performance of N-CDs/SnS2/CC composite counter electrode. The N-CDs/SnS2/CC composite electrode shows higher cathodic reduction current density and lower charge transfer resistance in CV and EIS measurements, respectively, as compared to those of the electrodes with N-CDs or SnS2 alone. Meanwhile, the DSSC using N-CDs/SnS2/CC exhibits cell efficiency (η) of 7.68%, which is higher than those of cells having SnS2/CC (η=7.54%) and N-CDs/CC (η=5.66%) counter electrodes, repectively; it also reaches 94% cell efficiency of the cell using Pt/CC counter electrode (η=8.15%). The design concept of the modification of the basal planes by defect-rich carbon dots (i.e., N-CDs) and highly-exposed edge sites (i.e., vertically-grown SnS2 nanosheets) makes promising route to enhance the performance of two-dimensional electro-catalysts.

A composite electrocatalytic poly(3,4-ethylenedioxythiophene) film incorporated with silver nanowires for bifacial dye-sensitized solar cells

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a superior electrocatalyst for dye-sensitized solar cells (DSSCs). The porous PEDOT film, however, lacks directional conduction paths, resulting in slower electron transfer and lower cell efficiency. In this study, silver nanowires (Ag NWs) are incorporated into a PEDOT film to construct a PEDOT-coated Ag NW composite film, wherein the Ag NWs serve as highways for charge transport. The composite film is constructed by spreading Ag NWs on tin-doped indium oxide (ITO) glass via a three-step process (dip coating, brush painting, and thermal compression), followed by coating a PEDOT film via electropolymerization. The DSSC catalyzed by the PEDOT-coated Ag NW exhibited an efficiency of 9.22 % under one-sun illumination, outperforming platinum (9.09 % efficiency) and PEDOT (8.33 % efficiency) by increasing the short-circuit current density. Chemical state analyses were performed to determine the interactions between the Ag NWs and PEDOT. Impedance measurements and quantum chemical calculations were conducted to rationalize the functionality of the PEDOT-coated Ag NWs. Owing to its high transparency, the resulting DSSC achieves an efficiency of 6.74 % under rear illumination, demonstrating its high feasibility as a bifacial DSSC. The DSSC also exhibited high efficiencies ranging from 14.05 % to 19.69 % under front-side illumination at low intensities of 300–1000 lux.

Anion Effect on the CuII-Neocuproine Mediator and Its Electrocatalysts for Dye-Sensitized Solar Cells: Polymeric Chalcogenides of PEDOT-PEDTT and [Ag2(SePh)2]n.

The synthetical methodology for the [Cu(dmp)2]2+/1+ (dmp = 2,9-dimethyl-1,10-phenanthroline; neocuproine) complexes has been systematically investigated by using various copper precursors, including CuCl2, Cu(NO3)2, and Cu(ClO4)2. After an anion exchange to trifluoromethanesulfonimide (TFSI), the tetra-coordinated CuII(dmp)2(TFSI)2-Cu(ClO4)2 (7.43%) outperformed the penta-coordinated CuII(dmp)2(TFSI)(NO3)-Cu(NO3)2 (4.30%) and CuII(dmp)2(TFSI)(Cl)-CuCl2. Polymeric chalcogenides, including a conducting copolymeric electrode of PEDOT-PEDTT [PEDOT = poly(3,4-ethylenedioxythiophene); PEDTT = poly(3,4-ethylenedithiothiophene)] and a coordination polymeric electrode of silver bezeneselenolate ([Ag2(SePh)2]n; mithrene), are introduced as the electrocatalysts for [Cu(dmp)2]2+/1+ for the first time. After optimization, dye-sensitized solar cells (DSSCs) based on carbon cloth (CC)/AgSePh-30 (10.18%) showed superior electrocatalytic ability compared to the benchmark CC/Pt (7.43%) due to numerous active sites provided by electron-donating Se atoms, high film roughness, and bottom-up 2D charge transfer routes. The DSSC based on CC/PEDTT-50 (10.38%) also outperformed CC/Pt due to numerous active sites provided by electron-donating S atoms and proper energy band structure. This work sheds light on the future design and synthesis in Cu-complex mediators and functional polymeric chalcogenides for high-performance DSSCs.

Laser-induced nitrogen and boron co-doped graphene film for dye-sensitized solar cell applications

Heteroatom-doped graphenes play a crucial role in developing metal-free electrocatalysts for dye-sensitized solar cells (DSSCs). This work demonstrates an approach to synthesizing nitrogen and boron dual-doped porous graphene as an efficient DSSC counter electrode (CE) by one-step laser induction technology. The morphologies, crystal structure, and chemical composition of N and/or B-doped laser-induced graphene were characterized and confirmed by SEM, XRD, and XPS measurements. Electrochemical results indicate that the conductivity and electrocalalytic activity of the nitrogen and boron co-doped graphene (BN-LIG) for triiodide reduction were enhanced after B-doping. Hence, the DSSC based on BN-LIG CE achieved a power conversion efficiency of 4.99%, which is 90.9% of a DSSC with Pt CE.

Bi-metallic [Cu/Co(6mna)2]n metal organic chalcogenolate frameworks as high-performance electro-catalysts for dye-sensitized solar cells: a ligand-assisted bottom-up synthesis

Superior electro-catalytic activity of a heterogeneous bi-metallic [Cu/Co(6mna)2]n MOF was established by synergistic effects between conductive [Cu2(6mna)(6mn)NH4]n with 2D (–Cu–S–)n planes and porous [Co2(6mna)2]n with helical (–Co–S–)n chains.

Polyoxovanadate derived VN@C composite catalysts by different synthesis routes as Pt-free counter electrode for dye-sensitized solar cells

Vanadium-based nitrides have been applied as Pt-free counter electrodes (CEs) electro-catalysts for dye-sensitized solar cells (DSSCs) due to inexpensive cost and easy doping and modification. Herein, polyoxovanadate (NH4)2V6O16 assisted by melamine to prepare VN@C composites by five different synthesis routes, including solvothermal, sol–gel, hydrothermal, ball milling, and chemical mixing method. And then, five VN@C composites were assembled as CEs in the encapsulated DSSCs, and yielded power conversion efficiencies of 4.47, 5.04, 5.35, 5.49 and 6.11% for regenerate traditional I3−/I− shuttles by the photocurrent-photovoltage (J-V) test, respectively. The catalytic performances of VN@C composites CEs were assessed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization experiments, and the significant effects of different synthetic routes were confirmed. The results revealed that VN@C composite CEs prepared by chemical mixing method had higher catalytic performance in DSSCs, which is due to the improvement of conductivity and the high concentration of active sites.

VC@C composites derived from polyoxovanadate assisted by dicyandiamide as low-cost platinum-free counter electrode electrocatalyst for dye-sensitized solar cells

Vanadium-based carbides have been applied as Pt-free counter electrodes (CEs) electro-catalysts for dye-sensitized solar cells (DSSCs) due to the advantages of earth-abundant reserves, diverse composition, ease modification, and low cost. Herein, the polyoxovanadate (NH4)2V6O16 as V source assisted by dicyandiamide (C2H4N4) as C source via simply physical mixing by ball-milling to assemble VC@C precursors. And then, five different VC@C composites derived from precursors with mass ratios of dicyandiamide to polyoxovanadate of 5:1, 10:1, 15:1, 20:1 and 25:1 at 900 °C, and further achieved power conversion efficiencies (PCEs) of 5.4%, 5.6%, 6.6%, 6.2% and 5.1% as CEs for regenerate traditional I3−/I− couple in the encapsulated DSSCs, respectively. The effects of different mass ratio of dicyandiamide on the catalytic performances of VC@C composite CEs were also assessed using cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization experiments. The photocurrent-photovoltage (J-V) results indicated that VC@C composites CEs had high conductivity and rich number of active sites, which indicated that VC@C composites could be a cost-effective and high-performance alternative Pt-based CEs catalyst for DSSCs.

Photovoltaics literature survey (No. 181)

Photovoltaics literature survey (No. 181)

MoSe2-nanoflowers as bi-functional electro-catalyst: An efficient counter electrode material for dye-sensitized solar cells and electrode modifier for hydrazine sensor

In this study, we reported bi-functional role of molybdenum diselenide (MoSe2)-flowers as electro-catalyst for dye-sensitized solar cells (DSSCs) and electrochemical sensing applications. The counter electrode was fabricated by using MoSe2-flowers as counter electrode material. The highest power conversion efficiency (PCE) of ∼4.8% was obtained. In further studies, we constructed electrochemical sensor (hydrazine) by modifying the surface of glassy carbon electrode (GCE) with prepared MoSe2-flowers via drop casting method. The MoSe2/GCE showed good limit of detection of 1.3 μM including sensitivity of 0.419 μA/μM-cm2. The MoSe2/GCE also demonstrates selective nature for the determination of hydrazine.

MWCNT Aided Cobalt Antimony Sulfide Electrocatalyst for Dye-Sensitized Solar Cells and Supercapacitors: Designing Integrated Photo-Powered Energy System

The objective of this study is to demonstrate low-cost Pt-free Dye-Sensitized Solar Cells (DSSCs) and an electrode for supercapacitor. Cobalt Antimony Sulfide (CoSbS) and Multiwalled Carbon Nanotubes supported CoSbS (CoSbS/MWCNT) composites are synthesized by a simple hydrothermal technique and are used as an electrocatalyst for the reduction of tri-iodide to iodide (). The crystalline structure, morphology, and quantum states of the synthesized samples are analyzed. In a series of electrochemical studies, the CoSbS/MWCNT demonstrated superior electroconductivity and electrocatalytic activity over pristine CoSbS. Notably, the Power Conversion Efficiency (PCE) is reached 6.0% with the CoSbS/MWCNT counter electrode, outpacing the corresponding CoSbS (4.4%) and Co9S8 (1.8%). It is also an effective material for supercapacitors. Moreover, CoSbS/MWCNT has the maximum specific capacity of 382 C g−1 with 3 A g−1 with the acceptable capacitance retention of around 82% over 1000 charge-discharge cycles and excellent rate capability (∼143 C g−1 at 3 A g−1). Through these findings, it can be discovered that CoSbS/MWCNT is not only a feasible substitute for the standard Pt counter electrode in DSSCs but also has the capacity to store energy. The excellent conversion and storage performance highlight the potential of CoSbS/MWCNT for a photo-powered energy system.

Sheet-like porous MoO2/MoP nanoparticles as counter electrocatalysts for dye-sensitized solar cells

The interfacial MoO2/MoP with high power conversion efficiency promotes the development of a low-power environmental-friendly Pt-free counter electrode.

Hierarchical pompon-like cobalt phosphide as a platinum-free electrocatalyst for dye-sensitized solar cells

Hierarchical 3D CoP micro-pompon assembled by 1D-nano-needle-array decorated 2D-micro-sheets provided facile charge transfer and lots of electrocatalytic active sites to deliver decent DSSC performance (8.80% at 1 sun; 17.27% at 7 klux).

Screen-printed carbon black/SiO2 composite counter electrodes for dye-sensitized solar cells

Platinum (Pt)-based counter electrodes (CEs) are promising electrocatalysts for dye-sensitized solar cells (DSSCs). However, replacing the expensive Pt with low-cost materials and comparable catalytic activity still a big challenge. Here, we prepared CB-SiO2 composites by blending various weights of SiO2 (1, 3, and 5 wt%) with carbon black (CB), followed by screen printed onto the FTO substrate to utilized as CEs for DSSCs. In comparison with pure CB, CB-SiO2 composite CEs showed higher transferability and higher electrocatalytic activity toward I3-/I- redox couple. Among all, CB-SiO2-1% composite CE with 4 µm showed the best catalytic performance, and the related DSSC showed a power conversion efficiency of 6.38%. Increasing the CE thickness significantly enhances the catalytic ability and the total performance of the assembled devices, whereas the power conversion efficiency of the DSSC with CB-SiO2-1% composite CE in 8 µm thick was 7.99%, which is close to that achieved by Pt-based device under the same conditions.

Recent Advances on Pt-Free Electro-Catalysts for Dye-Sensitized Solar Cells.

Since Prof. Grätzel and co-workers achieved breakthrough progress on dye-sensitized solar cells (DSSCs) in 1991, DSSCs have been extensively investigated and wildly developed as a potential renewable power source in the last two decades due to their low cost, low energy-intensive processing, and high roll-to-roll compatibility. During this period, the highest efficiency recorded for DSSC under ideal solar light (AM 1.5G, 100 mW cm−2) has increased from ~7% to ~14.3%. For the practical use of solar cells, the performance of photovoltaic devices in several conditions with weak light irradiation (e.g., indoor) or various light incident angles are also an important item. Accordingly, DSSCs exhibit high competitiveness in solar cell markets because their performances are less affected by the light intensity and are less sensitive to the light incident angle. However, the most used catalyst in the counter electrode (CE) of a typical DSSC is platinum (Pt), which is an expensive noble metal and is rare on earth. To further reduce the cost of the fabrication of DSSCs on the industrial scale, it is better to develop Pt-free electro-catalysts for the CEs of DSSCs, such as transition metallic compounds, conducting polymers, carbonaceous materials, and their composites. In this article, we will provide a short review on the Pt-free electro-catalyst CEs of DSSCs with superior cell compared to Pt CEs; additionally, those selected reports were published within the past 5 years.

Rational Design of NiCo2S4 Quantum Dot-Modified Nitrogen-Doped Carbon Nanotube Composites as Robust Pt-Free Electrocatalysts for Dye-Sensitized Solar Cells

Composite materials made of bimetallic sulfide quantum dots and carbon nanotubes are promising electrocatalysts due to the large specific surface area and synergistic effect between sulfides and ca...

MoS2 nanorods anchored reduced graphene oxide nanohybrids for electrochemical energy conversion applications

Herein, the hydrothermal route has been explored to design a novel network of molybdenum sulfide (MoS 2 ) nanorods/reduced graphene oxide (rGO) by varying wt% of MoS 2 (10–30 wt%) for the highly stable and efficient electrochemical energy conversion applications involving dye sensitized solar cells (DSSCs); and direct methanol fuel cells (DMFCs). The MoS 2 /rGO nanohybrids network has been systematically characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). XRD, HRTEM, Raman and XPS investigations confirmed the uniform and homogenous anchoring of MoS 2 nanorods on the rGO sheets in the MoS 2 /rGO nanohybrids. It has been revealed that the wt% of MoS 2 in MoS 2 /rGO nanohybrids strongly affects the anchoring of MoS 2 nanorods on rGO sheets which in turn affects their electrocatalytic behavior. The optimized MoS 2 /rGO nanohybrids with 20 wt% of MoS 2 nanorods exhibited long term stability and highly efficient electrocatalytic behavior. DSSCs assembled with MoS 2 /rGO nanohybrids as CE exhibited comparable power conversion efficiency (PCE) relative to standard DSSC. The optimized anchoring of MoS 2 on rGO sheets resulted in high current density as compared to rGO based electrocatalyst in MORs. Moreover, reproducibility of CV curves revealed high stability of MoS 2 /rGO nanohybrids under harsh electrolyte medium. • Synthesis of novel network of molybdenum sulfide nanorods (MoS 2 )/ reduced graphene oxide (rGO) using hydrothermal method. • Optimized MoS 2 /rGO nanohybrids (20 wt% of MoS 2 ) exhibits long term stability and high electrocatalytic behavior. • MoS 2 /rGO nanohybrids act as effective replacement of Pt electrocatalyst in DSSCs and methanol oxidation reactions in DMFCs.

Rational Design of Hierarchical Structural CoSe@NPC/CoSe@CNT Nanocomposites Derived from Metal-Organic Frameworks as a Robust Pt-free Electrocatalyst for Dye-Sensitized Solar Cells.

Transition-metal compounds/carbon hybrids with high electrocatalytic capability possess attractive potential as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). However, the simple structure and agglomeration always result in poor performance. Herein, cobalt selenides confined in hollow N-doped porous carbon interconnected by carbon nanotubes (CNTs) with cobalt selenides encapsulated inside (denoted as CoSe@NPC/CoSe@CNTs) are formed through in situ pyrolysis and selenization process. In this strategy, ZIF-67 is used as the precursor, structure inducer, and carbon source for the orientated growth of CNTs. Such a rational architecture provides a stable interconnected conductive network and a hierarchically porous structure, with more available active sites and a shortened pathway for charge transport, synergistically enhancing the electrocatalytic activity. Specifically, the DSSCs based on CoSe@NPC/CoSe@CNTs demonstrate a high efficiency of 7.36%, even superior to that of Pt (7.16%). Furthermore, the CoSe@NPC/CoSe@CNT CE also demonstrates a good long-term stability in the iodine-based electrolyte.

Highly Active Carbon-Based Electrocatalysts for Dye-Sensitized Solar Cells: A Brief Review

Dye-sensitized solar cells (DSSCs) have emerged as promising alternatives to traditional silicon-based solar cells due to their relatively high conversion efficiency, low cost, flexibility, and environmentally benign fabrication processes. In DSSCs, platinum (Pt)-based materials used as the counter electrode (CE) exhibit the superior catalytic ability toward the reduction reaction of triiodide ions, which are attributed to their excellent catalytic activity and high electrical conductivity. However, Pt-based materials with high cost and limited supply hinder them from mass production. Developing highly active and stable CE materials without noble metals has been a persistent challenge for the practical application in DSSCs. Recently, a number of earth-abundant catalysts, especially carbon-based materials, display high activity, low cost, and good stability that render them attractive candidates to replace Pt in DSSCs. Herein, we will briefly review recent progress on carbon-based electrocatalysts as CEs in DSSC applications. The strategies of improving the catalytic activity of carbon-based materials such as structural engineering and/or heteroatom doping will be introduced. The active sites toward the reduction reaction of triiodide ions summarized from experimental results or theoretical calculation will also be discussed. Finally, the futuristic prospects and challenges of carbon-based electrocatalysts as CEs in DSSCs will be briefly mentioned.

Metal–organic framework-derived cobalt diselenide as an efficient electrocatalyst for dye-sensitized solar cells

In this paper, cobalt-based metal–organic framework (Co-MOF) precursor is synthesized on fluorine-doped tin oxide (FTO) glass through an electrodeposition and solvothermal process. Then, cobalt diselenide (CoSe2-D) film is directly obtained through a selenization process. Meanwhile, Co-MOF film is also fabricated by spraying Co-MOF solution onto FTO glass, and selenized to form CoSe2 (CoSe2-S) film. It is found that CoSe2-S film is composed of particles with porous structure, which is beneficial to increase electrocatalytic active sites and provide more diffusion channels for the I−/I3− redox couples. As a result, CoSe2-S counter-electrode (CE) displays a higher electrocatalytic performance than those of platinum (Pt) and CoSe2-D CEs. The photoelectric conversion efficiency of the dye-sensitized solar cell (DSC) based on CoSe2-S CE is up to 6.86%, which is larger than that of the DSC based on Pt CE (6.36%). The results indicate the potential of using CoSe2 as low-cost and facile CE for DSCs.

Highly efficient, cost-effective counter electrodes for dye-sensitized solar cells (DSSCs) augmented by highly mesoporous carbons

In dye-sensitized solar cells (DSSCs), the electrocatalyst plays a crucial role in the counter electrode as it appreciably influences the overall efficiency of DSSC. The electrocatalyst enhances the rate of the reduction reaction that converts tri-iodide into iodide ions at the counter electrode-electrolyte interface and prevents the recombination of cations in the electrolyte and the photo-generated electrons in the semiconducting material. In any catalytic process, the surface area of the electro-catalyst in the counter electrode determines the number of sites available for interactions between the reactants and the catalyst, and consequently enhances the rate of the reaction. Here, we demonstrate that electrodes based on highly mesoporous carbon (HMC) can serve as inexpensive alternatives to platinum as the electrocatalyst in DSSC. In addition, we report for the first time a systematic investigation of several materials parameters and correlate to their photovoltaic performance. In the DSSCs experiments, the HMCs display high electrocatalytic activity with power conversion (up to 8.77%) which interestingly not only outperforms other reported porous carbons but also outperforms the conventional DSSCs with Pt catalyst.