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Precious platinum counter electrode (CE) has been an economic burden for future commercialization of dye-sensitized solar cells (DSSCs). Low-platinum alloy CE catalysts are promising in bringing down the solar cell cost without reducing photovoltaic performances. We present here a facile strategy of fabricating ZnO nanorods assisted platinum-nickel (PtNi) alloy microtube CEs for liquid-junction DSSCs. By adjusting the concentration of zinc precursors, the ZnO nanostructures and therefore PtNi alloys are optimized to maximize the electrocatalytic behaviors toward triiodide reduction reaction. The maximal power conversion efficiency is determined as high as 8.43% for liquid-junction DSSC device with alloyed PtNi microtube CE synthesized at 75 mM Zn(NO 3 ) 2 aqueous solution, yielding a 32.8% enhancement in cell efficiency in comparison with the solar cell from pristine platinum electrode. Moreover, the dissolution resistance and charge-transfer ability toward redox couples have also been markedly enhanced due to competitive dissolution reactions and alloyed effects. [ABSTRACT FROM AUTHOR]

Creation of transparent counter electrode (CE) electrocatalysts for bifacial dye-sensitized solar cells (DSSCs) is a persistent objective for reducing cost of photovoltaic conversion. We present here the experimental realization of highly transparent CuSe CEs by a mild solution method for liquid-junction bifacial DSSCs. The resultant CuSe CEs show superior electrocatalytic activity toward I 3 − reduction reaction. By optimizing the pH values in synthesizing CuSe electrodes, the maximal front efficiency of 6.21% and rear efficiency of 4.72% are recorded on the corresponding bifacial DSSC. Both catalytic activity and photovoltaic performances can be further elevated by alloying CuSe with Co or Fe, yielding promising efficiencies of 7.81% and 5.38% under front and rear irradiations, respectively. [ABSTRACT FROM AUTHOR]

Creation of cost-effective and platinum-free counter electrodes (CEs) is persistent for developing advanced dye-sensitized solar cells (DSSCs). We present here the fabrication of conducting polymers such as polyaniline (PANi), polypyrole (PPy), or poly(3,4-ethylenedioxythiophene) (PEDOT) intercalated reduced graphene oxide (rGO) CEs on flexible Ti foil or polyethylene-terephthalate substrate for liquid-junction DSSC applications. The ration architecture integrates the high electron-conducting ability of graphene and good electrocatalytic activity of a conducting polymer into a single CE material. The preliminary results demonstrate that the resultant CEs follow an order of rGO/PPy > rGO/PANi > rGO/PEDOT > rGO. A maximal cell efficiency of 6.23% is determined on the optimized solar cell device, yielding 104.9% enhancement in comparison to rGO based device. [ABSTRACT FROM AUTHOR]

One of the challenges in developing advanced dye-sensitized solar cells (DSSCs) is the pursuit of cost-effective and robust counter electrodes (CEs). We present here the successful synthesis of binary Pt x M 100−x (M = Ni, Co, Fe) alloy nanostructures on Ti foil by a facile and environmental-friendly strategy for utilization as CEs in liquid-junction DSSCs. Due to the reasonable charge-transfer ability and excellent electrocatalytic activity, the resultant DSSC yields a promising power conversion efficiency (PCE) of 6.42% with binary Pt 0.28 Ni 99.72 CE in comparison with 6.18% for pristine Pt CE based device. The easy synthesis, cost-effectiveness, and good electrocatalytic property may help the Pt 0.28 Ni 99.72 nanostructure stand out as an alternative CE electrocatalyst in a DSSC. [ABSTRACT FROM AUTHOR]

Pursuit of cost-effective counter electrode (CE) electrocatalysts with no sacrifice of photovoltaic performances has been a persistent objective for advanced dye-sensitized solar cell (DSSC) platforms. Here we demonstrate the experimental realization of CE electrocatalysts from Cu@M@Pt (M = Fe, Co, Ni) coaxial alloy nanowires for efficient DSSCs. The reasonable electrocatalytic activity is attributed to work function matching of alloy CEs to potential of I − / I 3 − and redistribute the electronic structure on the Pt surface. In comparison with 8.48% for the Pt nanotube CE based DSSC, the solar cells yield power conversion efficiencies up to 8.21%, 7.85%, and 7.30% using Cu@Fe@Pt, Cu@Co@Pt, and Cu@Ni@Pt NWs, respectively. This work represents an important step forward, as it demonstrates how to make the CE catalyst active and to accelerate the electron transport from CE to electrolyte for high-efficiency but cost-effective DSSC platforms. [ABSTRACT FROM AUTHOR]

Pursuit of cost-effective counter electrode (CE) electrocatalysts with no sacrifice of photovoltaic performances has been a persistent objective for dye-sensitized solar cells (DSSCs). Here we demonstrate the galvanic replacement realization of cost-effective CEs from Fe@M (M = Pd, Pt) nanospheres for DSSCs. Due to the enhanced catalytic activity originated from compressive strain and extended surface in tuning the electronic structure of Pd (or Pt) shell along with competitive dissolution reaction of Fe with electrolyte, the cells with high durability display efficiencies of 8.74% and 7.22%. The impressive results along with simple synthesis highlight the potential application of Fe@M nanospheres in robust DSSCs. [ABSTRACT FROM AUTHOR]

Pursuit of a high efficiency and stability has been a persistent objective for quantum dot-sensitized solar cells (QDSCs). Here we launch a strategy of synthesizing graphene implanted polyacrylamide (PAAm-G) conducting gel electrolytes for quasi-solid-state QDSCs. With an aim of elevating the dosage of S 2− /S x 2− redox couples and therefore charge-transfer ability, both osmotic press across the PAAm-G and capillary force within the three-dimensional micropores are utilized as driving forces. A promising power conversion efficiency of 2.34% is recorded for the QDSCs by optimizing graphene dosage in the conducting gel electrolyte. The enhanced conversion efficiency of solar cell is attributed to the expanded catalytic area from counter electrolyte/electrolyte interface to both interface and the conducting gel electrolyte. [ABSTRACT FROM AUTHOR]

High power conversion efficiency and cost-effectiveness are two persistent objectives for dye-sensitized solar cell (DSSC). Electricity generation from either front or rear side of a bifacial DSSC has been considered as a facile avenue of bringing down the cost of solar-to-electric conversion. Therefore, the fabrication of a transparent counter electrode (CE) with a high electrocatalytic activity is a prerequisite to realize this goal. We present here the feasibility of utilizing transparent cobalt selenide (Co–Se) binary alloy counter electrode for bifacial DSSC application, in which binary Co–Se alloy electrode is synthesized by a mild solution strategy and the cell device is irradiated by either front or rear side. Due to the high optical transparency, charge-transfer ability, and electrocatalytic activity, maximum front and rear efficiencies of 8.30% and 4.63% are recorded under simulated air mass 1.5 (AM1.5) irradiation, respectively. The impressive efficiency along with fast start-up, multiple start capability, and simple preparation highlights the potential application of cost-effective and transparent Co–Se alloy CE in robust bifacial DSSCs. [ABSTRACT FROM AUTHOR]

Pursuit of cost-effective and efficient counter electrodes (CEs) is a persistent objective for dye-sensitized solar cells (DSSCs). We present here the design of transparent Fe–Se nanoporous alloy CEs for bifacial DSSC applications. Due to the superior charge-transfer ability for I − /I 3 − redox couples, electrocatalytic reduction toward I 3 − species, and optical transparency in visible-light region, the bifacial DSSC with FeSe alloy electrode yields maximum front and rear efficiencies of 9.16% and 5.38%, respectively. A fast start-up, high multiple start capability, and good stability of the FeSe alloy CE demonstrate the potential applications in driving solar panels. The impressive efficiency along with simple preparation of the cost-effective Fe–Se nanoporous alloy CEs highlights their potential application in robust bifacial DSSCs. [ABSTRACT FROM AUTHOR]

Elevation of power conversion efficiency and reduction of electricity-generation cost have been two persistent objectives for quantum dot-sensitized solar cells (QDSSCs). Here we report a bifacial QDSSC structure having impressive power conversion efficiencies of 2.11% and 1.28% for front and rear irradiations, respectively. The device comprises a CdS-sensitized TiO 2 anode, a transparent cobalt selenide (Co–Se) counter electrode (CE), and a liquid electrolyte containing S 2− /S n 2− redox couples. Due to high optical transparency of the binary Co–Se alloy CE, incident light can penetrate the QDSSC from either front or rear side for electron excitation. A fast start-up and modest photocurrent stability are determined in the bifacial QDSSCs due to the high electron transfer kinetics in CdS-sensitized TiO 2 photoanode and electrocatalytic kinetics in Co–Se CE. [ABSTRACT FROM AUTHOR]

Pursuit of a high power conversion efficiency and reduction of electricity-generation cost has been a persistent objective for quantum dot-sensitized solar cells (QDSSCs). We present here the fabrication of a QDSSC comprising a nanoflower-structured CdS anode, a liquid electrolyte having S 2− /S n 2− redox couples, and a transparent CoSe counter electrode. Nanoflower-structured CdS anodes are prepared by a successive ionic layer adsorption and reaction (SILAR) method and subsequently hydrothermal strategy free of any surfactant or template. The CdS nanoparticles synthesized by a SILAR method act as “seed crystal” for growth of CdS nanoflowers. The average electron lifetime is markedly elevated in nanoflower-structured CdS anode in comparison with CdS nanoparticle or nanoporous CdS microsphere anode. Herein, we study the effect of synthesis method on CdS morphology and solar cell's photovoltaic performance, showing a power conversion efficiency of 1.67% and 1.17% for nanoflower-structured CdS QDSSC under front and rear irradiations, respectively. [ABSTRACT FROM AUTHOR]

Enhancement of light harvest for dye excitation is a persistent objective in dye-sensitized solar cell (DSSC). We present here the fabrication of titanium dioxide/calcium fluoride (TiO 2 /CaF 2 ) photoanodes for efficient DSSC applications. Owing to the interference effect of incident light beams reflected from TiO 2 /CaF 2 and CaF 2 /electrolyte interfaces, the light intensity and therefore dye excitation have been markedly enhanced. The crystal structure and therefore photovoltaic performance are optimized by adjusting CaF 2 dosage. A maximum power conversion efficiency of 7.66% is measured from the DSSC employing TiO 2 /0.5 wt% CaF 2 nanocrystallite in comparison with 6.02% for the solar cell with pristine TiO 2 anode. [ABSTRACT FROM AUTHOR]

Alloy materials have established themselves as alternative electrocatalysts for electrochemical devices because of their cost-effectiveness, high conductivity, good electrocatalytic activity, and reasonable stability. Aiming at reducing fabrication cost without sacrificing power conversion efficiency of dye-sensitized solar cells (DSSCs), we report the feasibility of designing transparent and cost-effective Fe–Se alloy counter electrodes for bifacial DSSCs. Due to the rapid charge transfer ability and electrocatalytic activity, maximum front and rear efficiencies of 7.64% and 4.95% are measured for the DSSC with FeSe alloy electrode in comparison with 6.97% and 3.56% from Pt-based solar cell. The impressive results along with simple synthesis highlight the potential application of Fe–Se alloys in robust bifacial DSSCs. [ABSTRACT FROM AUTHOR]

Storage of liquid electrolyte has been a persistent objective for liquid-state flexible dye-sensitized solar cells (DSSCs). We present here the feasibility of rear-irradiated flexible DSSC comprising of groove stored dye-sensitized TiO 2 on a Ti foil and conductive plastic supported transparent cobalt selenide alloy counter electrode. After being injected into the groove, the liquid electrolyte containing I − /I 3 − redox couples can be well sealed. The flexible cells are optimized by adjusting groove depth and stoichiometry of cobalt selenide electrodes, generating a maximum power conversion efficiency of 7.52% under one sun irradiation. The research demonstrates some new insights on how to improve liquid electrolyte retention and elevate photovoltaic performances of flexible DSSCs. [ABSTRACT FROM AUTHOR]

Enhancement of power conversion efficiency has been a long-term objective for dye-sensitized solar cells (DSSCs). In the current work, mesoporous TiO 2 anodes are synthesized by a gel-hydrothermal method using polyvinylpyrrolidone (PVP) as a pore-forming agent in order to elevate the dye loading, incident light illumination for dye excitation as well as electron transportation along conducting channels from TiO 2 nanoparticles. In comparison with dense TiO 2 anode, the dye illumination is also significantly enhanced, resulting in an increased photoelectron density on conduction band of TiO 2 . The photovoltaic performances are optimized by adjusting PVP dosage in synthesizing mesoporous TiO 2 anode. An impressive power conversion efficiency of 9.86% is recorded under one sun illumination. The power conversion efficiency is increased by ∼53.8% in comparison with the dense TiO 2 anode based DSSC. The high conversion efficiency in combination with simple preparation demonstrates the potential use of the approach in designing efficient DSSCs. [ABSTRACT FROM AUTHOR]

Abstract: Liquid electrolytes containing redox species have been widely used in dye-sensitized solar cells (DSSCs), whereas the volatility of organic solvents has been a tremendous obstacle for their commercial application. To assemble durable DSSCs, here we report the synthesis of full-ionic liquid electrolyte, in which 1-butyl-3-methylimidazolium nitrate is employed as solvent and 1-methyl-3-propylimidazolium iodide is iodide source. Using the imbibition performance of amphiphilic poly(acrylic acid/gelatin) [poly(AA/GR)] and poly(acrylic acid/cetyltrimethyl ammonium bromide) [poly(AA/CTAB)] matrices, full-ionic liquid electrolytes are imbibed into three-dimensional framework of poly(AA/GR) or poly(AA/CTAB) to form stable gel electrolytes. Room-temperature ionic conductivities as high as 17.82 and 18.44 mS cm−1 are recorded from full-ionic liquid imbibed poly(AA/GR) and poly(AA/CTAB) gel electrolytes, respectively. Promising power conversion efficiencies of 7.19% and 7.15% are determined from their DSSC devices in comparison with 6.55% and 6.12% from traditional acetonitrile-based poly(AA/GR) and poly(AA/CTAB) gel electrolytes, respectively. The new concept along with easy fabrication demonstrates the full-ionic liquid electrolytes to be good alternatives for robust gel electrolytes in quasi-solid-state DSSCs. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) gel electrolytes are versatile in elevating encapsulation of liquid electrolyte in dye-sensitized solar cells (DSSCs), however, the poor contact at gel electrolyte/Pt counter electrode interface is unfavorable in electrocatalyzing triiodide ions. In the current work, we report the multifunctions of graphene, graphene oxide, or nanographite incorporated microporous poly(acrylic acid)-cetyltrimethylammonium bromide (PAA-CTAB) conducting gel electrolytes in both sealing liquid electrolyte and conducting refluxed electrons (electrons from external circuit to Pt counter electrode) into 3D framework of the conducting gel electrolyte, aiming at elevating liquid electrolyte content in per unit volume of gel electrolyte, increasing electrocatalytic area toward triiodide ions and diminishing charge-transfer resistance. The electrical and electrochemical performances of the resultant conducting gel electrolytes are thoroughly characterized. Light-to-electric power conversion efficiencies of 7.06%, 6.35%, and 6.17% are determined from DSSCs using graphene, graphene oxide, and nanographite incorporated PAA-CTAB conducting gel electrolytes in comparison with 6.07% from pure PAA-CTAB based DSSC. [Copyright &y& Elsevier]

With an aim of enhancing anhydrous proton conductivity and phosphoric acid (H3PO4) retention, we here report the employment of three-dimensional (3D) polyacrylamide- graft-chitosan (PAAm- g-CS) frameworks as supporters to load enormous H3PO4. Intrinsic microporous structure can seal H3PO4 molecules in the interconnected 3D frameworks of PAAm- g-CS matrix during a dehydration process. The hydrogel membranes are thoroughly characterized by morphology observation, structural analysis, swelling kinetics, proton-conducting performances as well as electrochemical behaviors. Results show that H3PO4 loading and therefore proton conductivity of the resultant PEMs are dramatically improved by employing PAAm- g-CS matrix in comparison with H3PO4-doped polybenzimidazole membranes. The highest H3PO4 loading and anhydrous proton conductivity are 92.2 wt % and 0.083 S cm-1 at 165 °C, respectively. The high H3PO4 loading, reasonable proton conductivity in combination with simple preparation, low cost, and scalable matrix demonstrates the potential use of PAAm- g-CS hydrogel membranes in high-temperature proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: With an aim of enhancing the light-to-electric power conversion efficiency of dye-sensitized solar cell (DSSC), here we synthesize PtRu nanofiber alloys using a low-temperature hydrothermal technique which are employed as counter electrodes (CEs) for DSSCs. Owing to the good electrical conduction and electrocatalysis, light-to-electric power conversion efficiencies of PtRu-based DSSCs have been elevated in comparison with that of Pt CE based DSSC. The DSSC employing PtRu3 alloy CE gives a power conversion efficiency of 6.80% in comparison with 6.17% from Pt-based DSSC. The reasonable conversion efficiency, simple preparation, and scalability demonstrate the potential use of PtRu alloys in efficient DSSCs. [Copyright &y& Elsevier]

Abstract: Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its clean, high efficiency, good durability, and easy fabrication. However, enhancement of power conversion efficiency and high cost of Pt counter electrode are still significant issues in commercial application of DSSCs. Herein, pyrrole–single wall nanotube (pyrrole–SWCNT) complexes are pioneerly synthesized by a reflux technique and subsequently in-situ polymerized and employed as counter electrodes (CEs) for DSSCs. Different from traditional polypyrrole/SWCNT (PPy/SWCNT) composites, the resultant PPy–SWCNT complexes are expected to fulfill the good electrical-conduction of SWCNT and electrocatalytic behaviors of PPy in accelerating electrochemical activity and charge transfer owing to the covalent bond between PPy (N atoms) and SWCNT (C atoms). The DSSCs employing PPy–SWCNT complex CEs exhibit significantly enhanced photovoltaic performances, in which a promising power conversion efficiency of 8.30% is obtained from PPy–2 wt‰ SWCNT complex CE in comparison with 6.31% from PPy-only CE. The high conversion efficiency, rapid charge-transfer in combination with simple preparation, relatively low cost, and scalability demonstrates the potential use of PPy–SWCNT complexes in robust DSSCs. [Copyright &y& Elsevier]

Abstract: With an aim of significantly enhancing charge-transfer ability of counter electrodes and therefore photovoltaic performances of dye-sensitized solar cells (DSSCs), here we pioneerly report the complexation of polyaniline (PANi) and graphene as well as their employment as counter electrodes (CEs) in efficient DSSCs. Owing to the covalent bond between PANi (N atoms) and graphene (C atoms), charge transfer kinetics is dramatically elevated, which can be confirmed by the enhancement on electrocatalytic activity toward triiodides and a decrease in charge-transfer resistance. A power conversion efficiency of 7.70% is determined from DSSC using PANi−8 wt‰ graphene complex CE in comparison with 6.40% from pure PANi CE-based DSSC. The high conversion efficiency, facile charge-transfer in combination with simple preparation, relatively low cost, and scalability demonstrates the potential use of PANi−graphene complexes in robust DSSCs. [Copyright &y& Elsevier]

Abstract: With an aim of elevating liquid electrolyte loading, ionic conductivity, and electrocatalytic activity of gel electrolyte toward triiodides, freeze-dried microporous poly(acrylic acid)–poly(ethylene glycol) (PAA–PEG) matrix is employed to uptake conducting polymers, such as polyaniline (PANi) and polypyrrole (PPy). An ionic conductivity of 19.18 mS cm−1 at 65 °C is obtained from PAA–PEG/PANi conducting gel electrolyte which is nearly similar to 19.22 mS cm−1 from pure liquid electrolyte. The conducting polymers can form interconnected channels within insulating microporous PAA–PEG matrix, therefore, the reduction reaction of triiodide ions in the dye-sensitized solar cells (DSSCs) can be extended from Pt/gel electrolyte interface to both interface and three-dimensional framework of microporous conducting gel electrolyte. The resultant DSSCs from PAA–PEG/PANi and PAA–PEG/PPy conducting gel electrolytes display power conversion efficiencies of 7.12% and 6.53%, respectively, which are much higher than 5.02% from pure PAA–PEG-based DSSC. The new concept along with easy fabrication promises the microporous conducting gel electrolytes to be good alternatives in efficient quasi-solid-state DSSCs. [Copyright &y& Elsevier]

Abstract: Proton exchange membrane (PEM), transferring protons from anode to cathode, is a key component in a PEM fuel cell. In the current work, a new class of PEMs are synthesized benefiting from the imbibition behavior of three-dimensional (3D) polyacrylamide-graft-chitosan (PAAm-graft-chitosan) frameworks to H3PO4 aqueous solution. Interconnected 3D framework of PAAm-graft-chitosan provides tremendous space for holding proton-conducting H3PO4. The highest anhydrous proton conductivity of 0.13 S cm−1 at 165 °C is obtained. A fuel cell using a thick membrane as a PEM showed a peak power density of 405 mW cm−2 with O2 and H2 as the oxidant and fuel, respectively. Results indicate that the interconnected 3D framework provides superhighway for proton conduction. The valued merits on anhydrous proton conductivity, huge H3PO4 loading, and easy synthesis promise the new membranes to be good alternatives as high-temperature PEMs. [Copyright &y& Elsevier]

Abstract: Volatility of organic solvent in liquid electrolyte has been tremendous obstacle for its application in dye-sensitized solar cells (DSSCs), here we designed an ionic liquid-imbibed polymer gel electrolyte using 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as solvent, 1-methyl-3-propylimidazolium iodide (MPII) as iodine source, and amphiphilic poly(hydroxyethyl methacrylate/glycerol) [poly(HEMA/GR)] as a placeholder. As an amphiphilic matrix, poly(HEMA/GR) material can swell in ionic liquid electrolyte to form a stable gel, benefiting from its extraordinary absorption. The imbibed ionic liquid electrolyte is stored into interconnected poly(HEMA/GR) framework. Resultant quasi-solid-state electrolyte is honored with high ionic conductivity (14.29 mS cm−1) at room temperature and good retention. The ionic liquid-imbibed poly(HEMA/GR) gel electrolyte-based DSSC gives an overall light-to-electric conversion efficiency of 7.15%. The new concept along with easy fabrication promises the ionic liquid-imbibed gel electrolytes good alternatives in efficient DSSCs. [Copyright &y& Elsevier]

Abstract: Amphiphilic poly(hydroxyethyl methacrylate/cetytrimethylammonium bromide) [poly(HEMA/CTAB)] gel with a three-dimensional framework is successfully fabricated and employed to integrate with polyaniline (PANi). The resultant PANi imbibed poly(HEMA/CTAB) gel electrolyte provides space for holding I−/I3 −, giving a similar conduction mechanism and ionic conductivity to that of liquid system. The caged liquid electrolyte cannot leak from the three-dimensional framework of gel electrolyte under pressure of cell assembly. Fourier transform infrared spectra, X-ray diffraction patterns, cyclic voltammograms as well as electrochemical impedance spectra are employed to evaluate the molecular structure, crystallinity, and the electrochemical behaviors, showing that the combination of PANi with poly(HEMA/CTAB) results in an enhanced ionic conduction, lowered charge-transfer resistance, and extended electrocatalytic reaction toward I−/I3 − redox couples from Pt/gel electrolyte interface to both interface and three-dimensional framework of the gel electrolyte. The resultant quasi-solid-state dye-sensitized solar cells based on PANi imbibed poly(HEMA/CTAB) gel electrolyte shows a light-to-electric conversion efficiency of 6.68%, which higher than that from PANi-free poly(HEMA/CTAB). [Copyright &y& Elsevier]

Abstract: This paper reports the first study that investigates H3PO4-imbibed polyacrylamide/poly(vinyl alcohol) (PAM/PVA) semi-interpenetrating polymer network (semi-IPN) hydrogel as a high-temperature proton exchange membrane (PEM). The extraordinary ability of the PAM/PVA hydrogel to absorb a large quantity of aqueous solution is fully utilized to achieve a high H3PO4 loading, resulting in high proton conductivity membranes. The anhydrous proton conductivity of a PAM/PVA semi-IPN hydrogel loaded with 73.5 wt% H3PO4 reaches 0.0525 S cm−1 at 183 °C in dry air. A fuel cell using the thick-film PAM/PVA hydrogel exhibits a peak power density of 0.225 W cm−2 at 183 °C with pure O2 and H2 as the oxidant and fuel, respectively. The synthesized membrane also shows excellent acid retention under mechanical load and high humidity, a valued characteristic for high-temperature PEMs. These performance-ensuring properties paired with a low-cost synthesis approach demonstrate the new membrane to be a viable candidate as a high-temperature PEM. [Copyright &y& Elsevier]

The feasibility and effectiveness of the electrostatic self-assembly technique are demonstrated for the fabrication of thermoplastically conducting multilayer films. The layer-by-layer self-assembly process is based on the alternating adsorption of low molecular weight (Mn) poly(acrylic acid) (PAA) and cetyltrimethyl-ammonium bromide-modified graphene oxide (GO) with three carbon layers. A unique conductivity percolation effect is observed at a percolation threshold (percolation bilayer number) because the carbon-carbon interlayer can be expanded by the diffusion of PAA molecular chains. The resultant multilayer films show typical positive/negative temperature coefficient effects because of the thermoplasticity of the PAA with low Mn. After being reduced from GO to graphene (G), the electrical conductivity of the resulting (PAA/G)n multilayer film is dramatically enhanced, and the percolation threshold occurs at a high bilayer number. The reasonable conductivities and the percolation effect make these films inherently interesting and potentially useful as components of advanced electronic devices. [ABSTRACT FROM AUTHOR]

Abstract: A separator is prepared based on natural and flexible eggshell membrane (ESM) for supercapacitor application. Morphology observation shows that the ESM is consisted of hierarchically ordered macroporous network. With a high decomposition temperature (>220°C), enough mechanical strength (σ max =6.59±0.48MPa, ɛ max =6.98±0.31%, respectively), and low water uptake and swelling property (<10%), ESM could be a promising candidate for supercapacitor separator. As expected, the supercapacitor with ESM separator exhibits outstanding electrochemical performances, such as low resistance, quick charge–discharge ability (τ is 4.76s), and good cyclic stability (92% retention after 10,000 cycles). However, the one with PE separator shows worse properties (high resistance, low specific capacitance, etc.). This research provides new insight into the preparation of natural, low-cost and high-performance separator for supercapacitor and other applications. [Copyright &y& Elsevier]

Abstract: A simple two-step method was introduced to improve the hydrogel mechanical strength by forming an interpenetrating network (IPN). For this purpose, we synthesized polyacrylate/polyacrylate (PAC/PAC), polyacrylate/polyacrylamide (PAC/PAM), polyacrylamide/polyacrylamide (PAM/PAM) and polyacrylamide/poly(vinyl alcohol) (PAM/PVA) IPN hydrogels. The PAC/PAC IPN and PAC/PAM IPN hydrogels showed compressive strength of 70 and 160kPa, respectively. For the PAM/PAM IPN and PAM/PVA IPN hydrogels, they exhibited excellent tensile strength of 1.2 and 2.8MPa, and elongations at break of 1750% and 3300%, respectively. A strain relaxation was also observed in the case of PAM series IPN hydrogels. From FTIR, TGA and SEM measurements, we confirmed that physical entanglement, hydrogen bonds and chemical crosslinking played major roles in improving hydrogel strength and toughening. The two-step technique contributes to the understanding of ideal networks, provides a universal strategy for designing high mechanical strength hydrogels, and opening up the biomedical application of hydrogels. [Copyright &y& Elsevier]

Abstract: Highly oriented polyaniline (PANI) fiber was prepared by a polymerization at higher temperature and growth in lower temperature. Poly(sodium styrenesulfonate)/polyaniline multilayer film (PSS/PANI) n was layer-by-layer molecular-level self-assembled by a simple technique. The morphology and structure of the oriented PANI fiber were characterized, showing an emeraldine state and ordered molecular structure. The growth process and surface topography of the (PSS/PANI) n multilayer film were characterized by UV–vis spectroscopy and atomic force microscopy. Absorbance plotted against the bilayers exhibited a linear dependence, indicating a progressive and uniform deposition process of the multilayer film. The (PSS/PANI) n multilayer film exhibited an electrical conductivity in the order of 1Scm−1, and when bilayer number exceeded a threshold value of 4, the conductivity of the multilayer film increased dramatically. The electrochemical properties were studied through cyclic voltammograms, and it was found that the electrochemical activity of the (PSS/PANI) n film increased with the increase of the bilayer number. [Copyright &y& Elsevier]

Abstract: In this article, we reported the synthesis, structure and electric field sensitivity of polyacrylate/polyaniline (PAA/PANI) and poly(2-acrylamido-2-methyl propylsulfonic acid-acrylic acid)/polyaniline [P(AMPS-AA)/PANI] conducting hydrogels with an interpenetrating polymer network (IPN) structure. Scanning electron microscope showed that the conducting hydrogels presented porous structures consisting of PANI nanofibers. The results of Fourier-transform infrared and X-ray diffraction revealed that the PANI was in its conductive emeraldine state and partial crystallization. The unique morphology and molecular structure of the conducting hydrogels were expected to show unusual electric field responses. The conducting hydrogels were subjected to an electric field in NaCl solution for bending behaviors. It was demonstrated that the electric field response was improved by increasing aniline dosage, applied voltage and concentration of aqueous NaCl solution. The bending mechanism was attributed to polyelectrolyte hydrogel matrix and emeraldine PANI nanofibers. [Copyright &y& Elsevier]

Abstract: Hydrogels have potential applications in many fields, but the poor mechanical strength has limited their further development. In this article, we designed a high-strength hydrogel with an interpenetrating network (IPN) structure from polyacrylamide (PAM) and poly(vinyl alcohol) (PVA). Synthesis parameters, such as PVA/AM mass ratio, crosslinker dosage and elongation time were carried out for high tensile strength and elongation. The results showed that chemical crosslinking, physical entanglement and PVA precipitates were the dominant parameters for the improvement of mechanical properties. The PVA structure transferred from crystal to amorphous due to intermolecular and intramolecular interactions (such as hydrogen bond and self-crosslinking). PVA precipitates scatterred in the brittle PAM matrix homogeneously which dispersed the applied stress and improved the hydrogel toughness. The tensile strength and elongation were extremely high, they were 2.4MPa and 3100%, respectively. The simple method is versatile in synthesizing high-strength IPN hydrogels using many kinds of polymer species. [Copyright &y& Elsevier]

In this article, we successfully designed and fabricated polyacrylate/poly(ethylene glycol) interpenetrating network (PAC/PEG IPN) hydrogel by a two-step technique. The influences of synthesis parameters, such as crosslinker dosage and neutralization degree of PAC, on the equilibrium swelling ratio (SR) of the PAC/PEG IPN hydrogel were investigated. Based on Flory theory, a simplified experiential formula $$ Q_{{{\text{H}}_{2} {\text{O}}}}^{5/3} = 14.72I^{ - 1} + 207.43 $$ was proposed. The results revealed that the theoretical SR of the PAC/PEG IPN hydrogel was consistent with experimental value in the presence of univalent salt solution. In this case, the SR of the hydrogel can be calculated without measurement. While for multivalent salt solutions, the theoretical and experimental results are inconsistent owing to chelations between carboxylic and carboxylate groups of the PAC/PEG hydrogels and the cations in the solution. [ABSTRACT FROM AUTHOR]

Abstract: Expanded graphite was ball milled with a planetary mill in air atmosphere, and subsequently thermal annealed. The samples were characterized by using X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). It was found that in the milling initial stage (less than 12h), the crystallization degree of the expanded graphite declined gradually, but after milling more than 16h, a recrystallization of the expanded graphite toke place, and ordered nanoscale expanded graphite was formed gradually. In the annealing initial stage, the non-crystallization of the graphite occurred, but, beyond an annealing time, recrystallizations of the graphite arise. Higher annealing temperature supported the recrystallization. The milled and annealed expanded graphite still preserved the crystalline structure as raw material and hold high thermal stability. [Copyright &y& Elsevier]

A simple two-step aqueous polymerization method was introduced to synthesize a polyacrylate/polyethylene glycol (PAC/PEG) interpenetrating network (IPN) hydrogel. On the basis of the effects of the ratio of PAC to PEG, neutralization degree, heavy-metal ion concentration, and temperature on the adsorption behavior of PAC/PEG IPN hydrogel toward Ni2+, Cr3+ and Cd2+, the preparation conditions were optimized. In our system, the greatest amount of Ni2+, Cr3+ and Cd2+ adsorbed were 102.34, 49.38 and 33.41 mg g-1, respectively. The adsorption abilities of a dried PAC/PEG composite and a swollen PAC/PEG IPN hydrogel were compared. It was found that the efficiency of removing metal ions using the swollen hydrogel was greater than that using the dried composite. The adsorption mechanism and model are also discussed. [ABSTRACT FROM AUTHOR]

In the present study we have chemically polymerized silica/polypyrrole (SiO2/PPy) nanocomposite in the presence of sodium dodecyl benzene sulfate (SDBS) as dopant and iron chloride (FeCl3) as oxidant. The SiO2/PPy nanocomposite presents an electrical conductivity of 32.41 S cm−1 and percolation threshold of 20 wt%. The resulting SiO2/PPy nanocomposites have been extensively characterized in terms of their molecular structure, particle size, morphology, stability, and electroactivity. These SiO2/PPy particles have a rather polydisperse morphology. The effects of synthesis parameters such as oxidant, PPy, SDBS, reaction temperature and time, on the electrical conductivity of the nanocomposite have been detailedly optimized. And the conducting nanocomposite presented a good environmental stability. [ABSTRACT FROM AUTHOR]

A simple two-step aqueous polymerization method was introduced to synthesize polyacrylate/polyethylene glycol (PAC/PEG) interpenetrating network (IPN) hydrogel. The sorption behaviors and mechanism were studied by the sorption of PAC/PEG IPN hydrogel to Fe3+ ion from aqueous solution. The experimental results revealed that the adsoption amount of Fe3+ ion using swollen hydrogels was much higher than that using the dried composite, they were 75.69 mg/g and 14.25 mg/g, respectively. The parameters, such as neutralization degree, acrylic acid (AA) dosages and temperature, on the sorption amount of PAC/PEG IPN hydrogel were detailedly investigated. [ABSTRACT FROM AUTHOR]

Polyacrylamide/poly(vinyl alcohol)/polyacrylamide/graphite interpenetrating network (PAM/PVA/PAM/G IPN) hydrogel is synthesized using a simple two-step polymerization method. The swelling behaviors of the hydrogel depend on the PVA, graphite, and crosslinker dosages, and swelling process is dominated by a relaxation of macromolecule chains. Owing to IPN structure, the hydrogel shows a good mechanical strength and thermal stability. On the other hand, the incorporation of graphite improves the conductivity of the hydrogel. [ABSTRACT FROM AUTHOR]

A two-step polymerization technique is introduced to synthesize polyacrylamide/polyacrylate interpenetrating network (PAM/PAC IPN) hydrogels. The swelling ratio of the IPN hydrogel increases with the increase of the PAC content in PAM/PAC, and is smaller than the traditional PAM or PAC superabsorbents. A non-Fickian mechanism is observed in the swelling process, and the swelling changes from non-Fickian mechanism to Fickian mechanism with the increase of polyacrylate dosage in the hydrogel. The IPN hydrogel has typical pH-sensitivity and on–off effect. The deswelling properties and methyl orange dye removal are carried out based on the chelation of the carboxylic/carboxylate groups on the hydrogels with multivalent cations in solution. The hydrogel is expected to be used in the removal of heavy metal ions and dyes. [ABSTRACT FROM AUTHOR]

The synthesis characterization and conductivities of polyaniline/expanded vermiculite intercalated nanocomposite are presented in this paper. The conductive emeraldine salt form of polyaniline is inserted into the interlayer of expanded vermiculite to produce the nanocomposite with high conductivity. The structures and properties are characterized by transmission electron microscopy x-ray diffraction spectroscopy fourier transform infrared spectroscopy thermogravimetry analysis and by the measurements of conductivity and stability. The results show that an intercalated nanocomposite with high conductivity and stability is obtained. The synthesis conditions are optimized to obtain the highest conductivity which is 6.80 S cm-1. [ABSTRACT FROM AUTHOR]

Abstract: Based on the unique absorbent characters and three-dimensional network structure of polyacrylamide (PAM) superabsorbent polymer, a photocatalytic degradable TiO2/PAM composite was synthesized by an aqueous solution polymerization method with N,N′-methylene bisacrylamide as crosslinker, potassium peroxydisulfate as initiator, acrylamide as monomer, and TiO2 (P-25) as functional filler. The photocatalytic degradability of the composite was evaluated using methyl orange as photodegradation target, and the recovery and reproducibility of the composite was investigated. It was found that TiO2/PAM composite had a good photocatalytic degradability, the composite also possessed a good reproducibility of photocatalytic degradability, which is possible to be used in practical process. [Copyright &y& Elsevier]

By converting the traditional solid–solid contact to solid–liquid contact, the buried interface of perovskite film is healed to release tensile strain and suppress halide segregation, which universally improves the efficiency and stability of a PSC. [Display omitted] • A universal liquid buried interface is fabricated to replace traditional solid–solid interface. • The weak van der Waals interaction releases the tensile strain. • A champion efficiency of 11.13 % and 14.05 % is achieved for CsPbIBr 2 and CsPbI 2 Br PSCs. • Suppressed halide segregation significantly improves the photostability of PSC. The residual tensile strain, which is induced by lattice and thermal expansion coefficient difference between upper perovskite film and underlying charge transporting layer, significantly deteriorates the power conversion efficiency (PCE) and stability of a halide perovskite solar cell (PSC). To overcome this technical bottleneck, herein, we propose a universal liquid buried interface (LBI) by introducing a low melting-point small molecule to replace traditional solid–solid interface. Arising from the movability upon solid-to-liquid phase conversion, LBI plays a role of "lubricant" to effectively free the soft perovskite lattice shrinkage or expansion rather than anchoring onto the substrate, leading to the reduced defects due to the healing of strained lattice. Finally, the inorganic CsPbIBr 2 PSC and CsPbI 2 Br cell achieve the best PCEs of 11.13 % and 14.05 %, respectively, and the photo-stability is improved by 33.3-fold because of the suppressed halide segregation. This work provides new insights on the LBI for making high-efficiency and stable PSC platforms. [ABSTRACT FROM AUTHOR]

The launching of 5G technology provides excellent opportunity for the prosperous development of Internet of Things (IoT) devices and intelligent wireless sensor nodes. However, deploying of tremendous wireless sensor nodes network presents a great challenge to sustainable power supply and self‐powered active sensing. Triboelectric nanogenerator (TENG) has shown great capability for powering wireless sensors and work as self‐powered sensors since its discovery in 2012. Nevertheless, its inherent property of large internal impedance and pulsed "high‐voltage and low‐current" output characteristic seriously limit its direct application as stable power supply. Herein, a generic triboelectric sensor module (TSM) is developed toward managing the high output of TENG into signals that can be directly utilized by commercial electronics. Finally, an IoT‐based smart switching system is realized by integrating the TSM with a typical vertical contact–separation mode TENG and microcontroller, which is able to monitor the real‐time appliance status and location information. Such design of a universal energy solution for triboelectric sensors is applicable for managing and normalizing the wide output range generated from various working modes of TENGs and suitable for facile integration with IoT platform, representing a significant step toward scaling up TENG applications in future smart sensing. [ABSTRACT FROM AUTHOR]

Arising from the multiple light scattering sites, the regulation on perovskite film growth, Type-II band alignment and matched lattice spacing of 3D round-comb Fe 2 O 3 @SnO 2 composites, the light harvesting and charge extraction are significantly improved, which helps the CsPbBr 3 PSCs achieve a champion PCE of 10.23 % and excellent moisture tolerance. [Display omitted] The precise design of an electron transport layer (ETL) to improve the light-harvesting and quality of perovskite (PVK) film plays a crucial role in the photovoltaic performance of n-i-p perovskite solar cells (PSCs). In this work, a novel three-dimensional (3D) round-comb Fe 2 O 3 @SnO 2 heterostructure composites with high conductivity and electron mobility induced by its Type-II band alignment and matched lattice spacing is prepared and employed as an efficient mesoporous ETL for all-inorganic CsPbBr 3 PSCs. Arising from the multiple light scattering sites provided by the 3D round-comb structure, the diffuse reflectance of Fe 2 O 3 @SnO 2 composites is increased to improve the light absorption of the deposited PVK film. Besides, the mesoporous Fe 2 O 3 @SnO 2 ETL affords not only more active surface for sufficient exposure to the CsPbBr 3 precursor solution but also a wettable surface to reduce the barrier for heterogeneous nucleation, which realizes the regulated growth of a high-quality PVK film with less undesired defect. Hence, both the light-harvesting capability, the photoelectrons transport and extraction are improved, and the charge recombination is restrained, delivering an optimized power conversion efficiency (PCE) of 10.23 % with a high short-circuit current density of 7.88 mA cm−2 for the c -TiO 2 /Fe 2 O 3 @SnO 2 ETL based all-inorganic CsPbBr 3 PSCs. Moreover, under lasting erosion at 25 °C and 85 % RH for 30 days and light-soaking (AM 1.5G) for 480 h in air atmosphere, the unencapsulated-device shows superiorly persistent durability. [ABSTRACT FROM AUTHOR]

The preferred platinum counter electrode (CE) has been a burden for commercialization of dye-sensitized solar cell (DSSC) due to high expense and chemical corrosion by liquid electrolyte. In the current study, we have successfully realized the multistep deposition of platinum alloy CEs including PtNi, PtFe, and PtCo for liquid-junction DSSC applications. The preliminary results demonstrate that the enhanced electrochemical activities are attributable to high charge-transfer ability and matching work functions of the PtM (M = Ni, Fe, Co) alloy CEs to redox potential of I − /I 3 − electrolyte. The resultant DSSCs yield impressive power conversion efficiencies of 8.65%, 7.48%, and 7.08% with PtNi, PtFe, and PtCo CEs, respectively. On behalf of the competitive reactions between transition metals with liquid electrolyte, the PtM alloy CEs display enhanced long-term stability. [ABSTRACT FROM AUTHOR]

Pursuit of technological implementation with no sacrifice of photovoltaic performances has been a persistent objective for dye-sensitized solar cells (DSSCs). We launch here the experimental realization of a class of DSSCs consisting of polyaniline (PANi) incorporated TiO 2 anodes, PANi counter electrodes (CEs), and iodide doped PANi solid-state electrolytes. The PANi filled in photoanode can inject electrons for dye recovery, whereas the PANi CE fulfills the function of reducing triiodide into iodide ions. In particular, the solid PANi electrolyte has an ability of catalyzing triiodide species, shortening charge diffusion path length, and recovering dye molecules at anode/electrolyte interface. The photovoltaic performances are optimized by adjusting assembly process and lithium iodide dosage, yielding a maximum efficiency as high as 3.1% in the resultant DSSC device accompanied with fast start-up, multiple start/stop cycling, and good stability under persistent irradiation. [ABSTRACT FROM AUTHOR]

Exploration of cost-effective counter electrodes (CEs) and enhancement of power conversion efficiency have been two persistent objectives for dye-sensitized solar cells (DSSCs). In the current work, polyaniline–multiwalled carbon nanotube (PANi–MWCNT) complexes are synthesized by a reflux method and employed as CE materials for bifacial DSSCs. Owing to the high optical transparency of PANi–MWCNT complex CE, the incident light from rear side can compensate for the incident light from TiO 2 anode. The charge-transfer ability and electrochemical behaviors demonstrate the potential utilization of PANi–MWCNT complex CEs in robust bifacial DSSCs. The electrochemical properties as well as photovoltaic performances are optimized by adjusting MWCNT dosages. A maximum power conversion efficiency of 9.24% is recorded from the bifacial DSSC employing PANi–8 wt‰ MWCNT complex CE for both irradiation, which is better than 8.08% from pure PANi CE. [ABSTRACT FROM AUTHOR]

Enhancement in power conversion efficiency is a persistent pursuit for solid-state dye-sensitized solar cells (DSSCs). We report an experimental strategy of synthesizing I − /I 3 − doped 3-hydroxypropionitrile/polyaniline (HPN/PANi) solid electrolytes, aiming at expanding I 3 − reduction reaction from electrolyte/counter electrode interface to solid electrolyte system and shortening the charge diffusion path length. The DSSC with HPN/1.0 wt% PANi shows an efficiency of 3.70% in comparison to 1.49% from the cell with pristine HPN. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its merits on clean, cost-effectiveness, relatively high efficiency, and easy fabrication. However, the reduction of fabrication cost without sacrifice of power conversion efficiencies of the DSSCs is a golden rule for their commercialization. Here we design a new binary ruthenium selenide (Ru–Se) alloy counter electrodes (CEs) by a low-temperature hydrothermal reduction method. The electrochemical behaviors are evaluated by cyclic voltammogram, electrochemical impedance, and Tafel measurements, giving an optimized Ru/Se molar ratio of 1:1. The DSSC device with RuSe alloy CE achieves a power conversion efficiency of 7.15%, which is higher than 5.79% from Pt-only CE based DSSC. The new concept, easy process along with promising results provide a new approach for reducing cost but enhancing photovoltaic performances of DSSCs. [ABSTRACT FROM AUTHOR]

Abstract: Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its merits on clean, low fabrication cost, relatively high power conversion efficiency, good durability, and easy assembly. However, the commercial application of DSSCs has been hindered by the high expenses of counter electrodes (CEs). With an aim of significantly enhancing the light-to-electric power conversion efficiency, here we pioneerly synthesize CoPt alloys using an electrochemically codeposition technique which are employed as CEs for efficient DSSCs. Owing to the rapid charge transfer, electrical conduction, and electrocatalysis, power conversion efficiencies of CoPt alloy CE-based DSSCs have been markedly elevated in comparison with that of the DSSC from Pt-only CE. The DSSC employing CoPt0.1 alloy CE gives an impressive power conversion efficiency of 9.59%, which is much higher than 6.86% from conversional Pt-based DSSC. The high conversion efficiency, low cost in combination with simple preparation, and scalability demonstrates the potential use of CoPt alloy CEs in efficient DSSCs. [Copyright &y& Elsevier]