An Interconnected Ternary MIn2S4 (M=Fe,Co, Ni) Thiospinel Nanosheet Array: A Type of Efficient Platinum‐Free Counter Electrode for Dye‐Sensitized Solar Cells

The ternary iron‐group thiospinels of metal diindium sulfides (MIn₂S₄, M=Fe, Co, Ni) with a vertically aligned nanosheet array structure are fabricated through an in situ solvothermal method on F‐doped tin oxide (FTO) substrates, which are employed as one type of platinum (Pt)‐free counter electrodes (CEs) in structure‐dependent dye‐sensitized solar cells (DSSCs). A DSSC assembled with ternary CoIn₂S₄ CE achieves an photoelectric conversion efficiency (PCE) of 8.83 %, outperforming than that of FeIn₂S₄ (7.18 %) and NiIn₂S₄ (8.27 %) CEs under full sunlight illumination (100 mW cm⁻², AM 1.5 G), which is also comparable with that of the Pt CE (8.19 %). Putting aside that the interconnected nanosheet array provides fast electron transfer and electrolyte diffusion channels, the highest PCE of CoIn₂S₄ based DSSC results from its largest specific surface area (144.07 m² g⁻¹), providing abundant active sites and the largest electron injection efficiency from CE to electrolyte.     

Enhanced Performance of Organic/Inorganic Hybrid Nanomaterials bearing Impregnated [PdL2] Complexes as Counter‐Electrode Catalyst for Dye‐Sensitized Solar Cells

N‐coordinate Pd²⁺ complexes [PdL₂] (L: N‐N‐quinoline‐8‐yl‐R‐benzenesulfonamides) ( 6–10 ) and [PdL₂] complexes assembled on multi‐wall carbon nanotubes (MWCNTs) hybrid nanomaterials were fabricated and characterized by various techniques. The [PdL₂] impregnated MWCNTs materials ( 11–15 ) were applied as a counter electrode (CE) catalyst for triiodide to iodide reduction reaction in the dye‐sensitized solar cells (DSSC) and investigated electro‐catalytic activities. The MWCNTs‐supported [PdL₂] CEs ( 11–15 ) are exhibits as Pt‐free CE with good power conversion efficiencies (PCEs), and compared to platinum and bare MWCNTs CEs and the PCE of bare MWCNTs was clearly improved by means of [PdL₂] complexes ( 6–10 ). The DSSCs based on the hybrid counter electrodes (CEs) ( 11–15 ) and bare MWCNTs are indicated a relative efficiency ( ? _rel ) of 64.27%, 54.07%, 53.75%, 51.52% 44.82% and 27.27% concerning a Pt CE control device set at 100%. The report emphasizes that [PdL₂] impregnated MWCNTs type counter electrodes (CEs) ( 11–15 ) are promising as effectively catalyst in working device design, particularly taking into account the eco‐friendly approach of the hybrids.     

碳纳米纤维负载Co3S4复合材料的合成及其在染料敏化太阳电池对电极的应用

采用水热法合成四硫化三钴（Co₃S₄）催化材料,并利用球磨和喷涂技术将其制备成对电极,结合新型无碘电解液Co²⁺/Co³⁺用于染料敏化太阳电池（dye-sensitized solar cells,简称DSCs）来研究其光电性能。测试结果显示,基于Co₃S₄对电极,DSCs的能量转化效率（power conversion efficiency,简称PCE）只有6.06%,远远低于Pt对电极（8.05%）。为了提高Co₃S₄的催化能力,采用静电纺丝技术制备碳纳米纤维（electrospun carbon nanofibers,简称ECs）,结合水热法制备出不同负载量的碳纳米纤维负载四硫化三钴（Co₃S₄/ECs）复合催化材料用于对电极,结果表明,Co₃S₄/ECs的PCE最高可达（8.22±0.08）%,优于Pt对电极。     

碳纳米纤维负载Co_3S_4复合材料的合成及其在染料敏化太阳电池对电极的应用

采用水热法合成四硫化三钴(Co_3S_4)催化材料,并利用球磨和喷涂技术将其制备成对电极,结合新型无碘电解液Co~(2+)/Co~(3+)用于染料敏化太阳电池(dye-sensitized solar cells,简称DSCs)来研究其光电性能。测试结果显示,基于Co_3S_4对电极,DSCs的能量转化效率(power conversion efficiency,简称PCE)只有6.06%,远远低于Pt对电极(8.05%)。为了提高Co_3S_4的催化能力,采用静电纺丝技术制备碳纳米纤维(electrospun carbon nanofibers,简称ECs),结合水热法制备出不同负载量的碳纳米纤维负载四硫化三钴(Co_3S_4/ECs)复合催化材料用于对电极,结果表明,Co_3S_4/ECs的PCE最高可达(8.22±0.08)%,优于Pt对电极。     

High‐Performance Platinum‐Free Dye‐Sensitized Solar Cells with Molybdenum Disulfide Films as Counter Electrodes

By using a radio‐frequency sputtering method, we synthesized large‐area, uniform, and transparent molybdenum disulfide film electrodes (1, 3, 5, and 7 min) on transparent and conducting fluorine‐doped tin oxide (FTO), as ecofriendly, cost‐effective counter electrodes (CE) for dye‐sensitized solar cells (DSSCs). These CEs were used in place of the routinely used expensive platinum CEs for the catalytic reduction of a triiodide electrolyte. The structure and morphology of the MoS₂ was analyzed by using Raman spectroscopy, X‐ray diffraction, and X‐ray photoemission spectroscopy measurements and the DSSC characteristics were investigated. An unbroken film of MoS₂ was identified on the FTO crystallites from field‐emission scanning electron microscopy. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel curve measurements reveal the promise of MoS₂ as a CE with a low charge‐transfer resistance, high electrocatalytic activity, and fast reaction kinetics for the reduction of triiodide to iodide. Finally, an optimized transparent MoS₂ CE, obtained after 5 min synthesis time, showed a high power‐conversion efficiency of 6.0 %, which comparable to the performance obtained with a Pt CE (6.6 %) when used in TiO₂‐based DSCCs, thus signifying the importance of sputtering time on DSSC performance.     

Highly Catalytic Carbon Nanotube/Pt Nanohybrid‐Based Transparent Counter Electrode for Efficient Dye‐Sensitized Solar Cells

Low‐cost transparent counter electrodes (CEs) for efficient dye‐sensitized solar cells (DSSCs) are prepared by using nanohybrids of carbon nanotube (CNT)‐supported platinum nanoparticles as highly active catalysts. The nanohybrids, synthesized by an ionic‐liquid‐assisted sonochemical method, are directly deposited on either rigid glass or flexible plastic substrates by a facile electrospray method for operation as CEs. Their electrochemical performances are examined by cyclic voltammetry, current density–voltage characteristics, and electrochemical impedance spectroscopy (EIS) measurements. The CNT/Pt hybrid films exhibit high electrocatalytic activity for I^?/I₃^? with a weak dependence on film thickness. A transparent CNT/Pt hybrid CE film about 100 nm thick with a transparency of about 70 % (at 550 nm) can result in a high power conversion efficiency (η) of over 8.5 %, which is comparable to that of pyrolysis platinum‐based DSSCs, but lower cost. Furthermore, DSSC based on flexible CNT/Pt hybrid CE using indium‐doped tin oxide‐coated polyethylene terephthalate as the substrate also exhibits η=8.43 % with J_sc=16.85 mA cm^?2, V_oc=780 mV, and FF=0.64, and this shows great potential in developing highly efficient flexible DSSCs.     

MnWO4/生物质衍生碳纳米复合催化剂的制备及催化性能

通过共沉淀法合成了双金属氧化物MnWO₄镶嵌生物质衍生碳（MnWO₄/BC）纳米复合催化剂,并将其作为对电极（counter electrode,CE）催化剂组装了染料敏化太阳能电池（dye-sensitized solar cell,DSSC）,探究了MnWO₄/BC在非碘体系中的催化性能和光伏性能。结果表明：在铜氧化还原（Cu²⁺/Cu⁺）电对DSSC中获得的光电能量转换效率（power conversion efficiency,PCE）为3.57%（D35）和1.59%（Y123）,高于Pt电极的PCE（3.12%,1.16%）;50次连续循环伏安测试表明,MnWO₄/BC催化剂具有较好的电化学稳定性。     

Copper doped manganese dioxide as counter electrode for dye-sensitized solar cells

Many materials have been tried as the counter electrode (CE) material as a substitute to the noble metal Pt in dye-sensitized solar cells (DSSCs). The CE property is critical to the operation of a DSSC as it catalyzes the reduction of I₃^- ions and retrieves the electrons from the photoanode. Here we have explored the application of manganese dioxide (MnO₂) and copper-doped manganese dioxide (Cu-MnO₂) nanoparticles as CE candidates for DSSCs mainly as low-cost alternatives to Pt. A simple hydrothermal method was followed to synthesize α-MnO2 and Cu-MnO2 nanoparticles at a temperature of 140 °C for 14 h. The nanoparticles were characterized to prove its electrocatalytic abilities for DSSCs. DSSC devices fabricated with 10 wt% Cu-MnO₂ as CE showed the best V_OC of 781 mV, I_SC of 3.69 mA/cm², FF of 0.50, and %PCE of 1.7 whereas Pt as CE showed V_OC of 780 mV, I_SC of 14.8 mA/cm², FF of 0.43, and %PCE of 5.83 under 0.85 Sun. The low-cost feature of using Cu-MnO₂ is encouraging to further study the factors that can improve the efficiency of DSSCs with alternative CEs to conventional Pt electrodes.     

A study of novel macrocyclic copper complex/graphene‐based composite materials for counter electrodes of dye‐sensitized solar cells

In this study, a newly synthesized macrocyclic copper complex, [Cu(C₁₀H₂₀N₈)(C₄H₈N₄)](BF₄)₂, was used for a reaction with graphene oxide. Macrocyclic copper complex/graphene‐based composite materials were prepared and applied to the counter electrodes (CEs) of dye‐sensitized solar cells (DSSCs). As the level of the macrocyclic copper complex increased, the catalytic sites on the surface of the CE increased. The results showed that the device efficiency of the composite GO/Cu (1:10) CE was 7.61%, which was better than that of the Platinum (Pt) CE (7.04%). The device efficiency of the DSSC was enhanced effectively because the electrocatalytic activity of the CE was enhanced, and the interface impedance of the device was reduced. Therefore, the macrocyclic copper complex/graphene‐based composite materials may have the potential to replace traditional Pt to increase efficiency and reduce the fabrication cost of DSSCs.     

Manipulating Coulombic Efficiency of Cathodes in Aqueous Zinc Batteries by Anion Chemistry

Electrolyte environments, including cations, anions, and solvents are critical for the performance delivery of cathodes of batteries. Most works focused on interactions between cations and cathode materials, in contrast, there is a lack of in-depth research on the correlation between anions and cathodes. Here, we systematically investigated how anions manipulate the coulombic efficiency (CE) of cathodes of zinc batteries. We take intercalation-type V₂O₅ and conversion-type I₂ cathodes as typical cases for profound studies. It was found that electronic properties of anions, including charge density and its distribution, can tune conversion or intercalation reactions, leading to significant CE differences. Using operando visual Raman microscopy and theoretical simulations, we confirm that competitive coordination between anions and I⁻ can regulate CEs by modulating polyiodide diffusion rates in Zn−I₂ cells. In Zn−V₂O₅ cells, anion-tuned solvation structures vastly affect CEs through varying Zn²⁺ intercalation kinetics. Conversion I₂ cathode achieves a 99 % CE with highly electron-donating anions, while anions with preferable charge structures that interact strongly with Zn²⁺ afford an intercalation V₂O₅ a nearly 100 % CE. Understanding the mechanism of anion-governed CEs will help us evaluate compatibility of electrolytes with electrodes, thus providing a guideline for anion selection and electrolyte design for high-energy, long-cycling zinc batteries.     

Low temperature fabrication of flexible carbon counter electrode on ITO-PEN for dye-sensitized solar cells

<正>A novel low temperature method was used to prepare the mesoporous carbon(MC) counter electrode(CE) on indium-doped tin oxide coated polyethylene naphthalate(ITO-PEN) for flexible dye-sensitized solar cells(DSSCs).The obtained flexible MC CEs with carbon loading of 280μg cm~(-2) were characterized by SEM,XRD and electrochemical impedance.The light-to-electricity conversion efficiency of the DSSC fabricated with the prepared flexible MC CE was 86%of that of DSSC based on the decomposited Pt CE.     

Self-supported metal sulphide nanocrystals-assembled nanosheets on carbon paper as efficient counter electrodes for quantum-dot-sensitized solar cells

Developing efficient counter electrodes (CEs) and quantum dots made of earth-abundant and non-toxic elements is essential but still challenging for quantum dot-sensitized solar cells (QDSSCs). Here, we report a facile strategy to prepare self-supported and robust CoS₂ and NiS nanocrystals-assembled nanosheets directly grown on carbon paper (MSx NS@CP) as efficient counter electrodes for QDSSCs. Such CEs integrate the merits of fast electron transfer from interconnected conductive scaffold, efficient mass transfer from hierarchically vertical nanosheet on 3D open substrate, as well as abundant highly active catalytic sites from metal sulphide nanocrystal units. As a result, QDDSCs based on such CoS₂ NS@CP and NiS NS@CP CEs achieve a PCE of 8.88% and 7.53%, respectively. The detailed analyses suggest that CoS₂ NS@CP has the highest catalytic activity and shows the lowest charger transfer resistance, leading to the highest PCE. These findings may inspire the design and exploration of other self-supported efficient CEs by integrating highly active catalysts onto 3D conductive networks for efficient QDSSCs.     

The Core/Shell Structure P Doped MoS2@Ni3S2 Nanorods Array for High Current Density Hydrogen Evolution in Alkaline and Acidic Electrolyte

Electrocatalysis is the most promising strategy to generate clean energy H₂, and the development of catalysts with excellent hydrogen evolution reaction (HER) performance at high current density that can resist strong alkaline and acidic electrolyte environment is of great significance for practical industrial application. Therefore, a P doped MoS₂@Ni₃S₂ nanorods array (named P-NiMoS) was successfully synthesized through successive sulfuration and phosphorization. P-NiMoS presents a core/shell structure with a heterojunction between MoS₂ (shell) and Ni₃S₂ (core). Furthermore, the doping of P modulates the electronic structure of the P-NiMoS; the electrons transfer from the t_2g orbital of Ni element to the e_g empty orbital of Mo element through the Ni−S−Mo bond at the Ni₃S₂ and MoS₂ heterojunction, facilitating the hydrogen evolution reaction. As a result, P-NiMoS exhibits excellent HER activity; the overpotential is 290 mV at high current density of 250 mA cm⁻² in alkaline electrolyte, which is close to Pt/C (282 mV@250 mA cm⁻²), and P-NiMoS can stably evolve hydrogen for 48 h.     

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.     

High-performance Pt-NiO nanosheet-based counter electrodes for dye-sensitized solar cells

High-performance counter electrodes for dye-sensitized solar cells (DSSCs) are fabricated with platinum-nickel oxide (Pt-NiO) nanosheets as catalytic materials. Firstly, the Pt-Ni nanosheets are synthesized via galvanic replacement reaction between pre-synthesized Ni nanosheets and an aqueous H₂PtCl₆ solution. Secondly, after thermal treatment in air, the Pt-Ni alloys are turned to Pt-NiO nanosheets. The related data of cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization reveal that Pt-NiO counter electrodes show highly catalytic activity and low charge transfer resistance. The DSSC with Pt-NiO counter electrode exhibits power conversion efficiency (PCE) of 8.40 %, which is lower than that of the DSSC containing commercial available Pt counter electrode (9.15 %) under full sunlight illumination (100 mW cm^?2, AM1.5G). However, owing to the extremely high transparency of Pt-NiO counter electrode, when putting an Ag mirror behind the back side of the DSSC, the reflected light can bring great enhanced PCE (11.27 %).     

Economical Pt-free catalysts for counter electrodes of dye-sensitized solar cells

Three classes (carbides, nitrides and oxides) of nanoscaled early-transition-metal catalysts have been proposed to replace the expensive Pt catalyst as counter electrodes (CEs) in dye-sensitized solar cells (DSCs). Of these catalysts, Cr(3)C(2), CrN, VC(N), VN, TiC, TiC(N), TiN, and V(2)O(3) all showed excellent catalytic activity for the reduction of I(3)(-) to I(-) in the electrolyte. Further, VC embedded in mesoporous carbon (VC-MC) was prepared through in situ synthesis. The I(3)(-)/I(-) DSC based on the VC-MC CE reached a high power conversion efficiency (PCE) of 7.63%, comparable to the photovoltaic performance of the DSC using a Pt CE (7.50%). In addition, the carbide catalysts demonstrated catalytic activity higher than that of Pt for the regeneration of a new organic redox couple of T(2)/T(-). The T(2)/T(-) DSCs using TiC and VC-MC CEs showed PCEs of 4.96 and 5.15%, much higher than that of the DSC using a Pt CE (3.66%). This work expands the list of potential CE catalysts, which can help reduce the cost of DSCs and thereby encourage their fundamental research and commercial application.     

Synthesis of Ternary Ni/Mo2C/Carbon Nanofibers as Low-cost Counter Electrode for Efficient Dye-sensitized Solar Cells

To reduce the cost of manufacture, it is urgent to develop efficient and stable platinum(Pt)-free counter electrode(CEs) electrocatalysts for dye-sensitized solar cells(DSSCs). In this study, a simple electrospinning and carbonization strategy has been developed to synthesize carbon nanofibers(CNFs) loaded with Ni and Mo₂C nanoparticles(Ni/Mo₂C/CNFs) as CE. Owing to the high electrical conductivity of CNFs and the large catalytic activity of Ni and Mo₂C, an excellent electrochemical performance of Ni/Mo₂C/CNFs as CE is achieved. The optimized DSSC assembled with Ni/Mo₂C(2:1)/CNFs-based CE exhibits a power conversion efficiency(PCE) of 8.90%, which exceeds the corresponding values of the device using the Pt(8.07%), Ni/Mo₂C(1:1)/CNFs(8.68%), Ni/Mo₂C(1:2)/CNFs(8.20%), Ni/CNFs(7.50%) and Mo₂C/CNFs(6.10%). This work provides a new strategy for developing effective and low-cost CE materials in DSSCs.     

Efficient Counter Electrode Manufactured from Ag2S Nanocrystal Ink for Dye‐Sensitized Solar Cells

It is generally believed that silver or silver‐based compounds are not suitable counter electrode (CE) materials for dye‐sensitized solar cells (DSSCs) due to the corrosion of the I^?/I₃^? redox couple in electrolytes. However, Ag₂S has potential applications in DSSCs for catalyzing I₃^? reduction reactions because of its high carrier concentration and tiny solubility product constant. In the present work, CE manufactured from Ag₂S nanocrystals ink exhibited efficient electrocatalytic activity in the reduction of I₃^? to I^? in DSSCs. The DSSC consisting of Ag₂S CE displayed a higher power conversion efficiency of 8.40 % than that of Pt CE (8.11 %). Moreover, the devices also showed the characteristics of fast activity onset, high multiple start/stop capability and good irradiated stability. The simple composition, easy preparation, stable chemical property, and good catalytic performance make the developed Ag₂S CE as a promising alternative to Pt CE in DSSCs.     

Ternary-organic photovoltaics with J71 as donor and two compatible nonfullerene acceptors

Recombining the advantages on photovoltaic parameters of two binary-organic photovoltaics (OPVs) into one ternary cell is an efficient strategy for selecting materials, in addition to the absorption spectra complementary among the used materials. The binary-OPVs with J71:BTP-4F-12 exhibit a power conversion efficiency (PCE) of 11.70%, along with a short-circuit-current-density (J_SC) of 23.61 mA cm⁻², an open-circuit-voltage (V_OC) of 0.841 V and a fill factor (FF) of 58.99%. Although the relatively low PCE of 10.92% and J_SC of 16.59 mA cm⁻² are achieved in J71:ITIC-based binary-OPVs, the V_OC of 0.935 V and FF of 70.40% are impressive compared with J71:BTP-4F-12-based OPVs. Optimal ternary-OPVs are achieved with J71:BTP-4F-12:ITIC as active layers by weight ratio of 1:0.48:0.72, delivering a markedly increased PCE of 13.05% with a V_OC of 0.903 V, a J_SC of 21.27 mA cm⁻² and a FF of 68.20%. An over 11.5% PCE improvement is obtained by recombining the advantages of binary-OPVs into ternary-OPVs with ITIC as photon harvesting reinforcing agent and morphology regulator. The good compatibility between BTP-4F-12 and ITIC provides large room to well optimize their relative content for achieving the well balanced three key photovoltaic parameters of ternary-OPVs.     

NiO/MnO_2分级纳米片阵列复合材料的制备与超电容性能

通过化学浴沉积和水热法在泡沫镍上制备了NiO/MnO_2分级纳米片阵列复合材料,XRD和SEM测试表明NiO纳米片垂直生长在泡沫镍上,交叉形成网状阵列结构;MnO_2纳米介孔泡沫进一步生长在NiO纳米片两侧,与NiO形成了壳核式的复合结构。循环伏安和恒流充放电测试发现,NiO/MnO_2分级纳米片阵列复合材料的电化学性能相比复合前得到明显改善,在1 A·g~(-1)的电流密度下,比电容提高至1 297 F·g~(-1);2 A·g~(-1)下循环1 000次,比电容保持率高达97%,比电容和循环性能的改善是由于分级纳米片阵列复合结构方便了电解液传质,扩大了活性材料与电解液的接触,促进了赝电容反应,提高了NiO和MnO_2的结构稳定性。