Functionalization of Tailored Porous Carbon Monolith for Decontamination of Radioactive Substances

As the control over radioactive species becomes critical for the contemporary human life, the development of functional materials for decontamination of radioactive substances has also become important. In this work, a three-dimensional (3D) porous carbon monolith functionalized with Prussian blue particles was prepared through removal of colloidal silica particles from exfoliated graphene/silica composite precursors. The colloidal silica particles with a narrow size distribution were used to act a role of hard template and provide a sufficient surface area that could accommodate potentially hazardous radioactive substances by adsorption. The unique surface and pore structure of the functionalized porous carbon monolith was examined using electron microscopy and energy-dispersive X-ray analysis (EDS). The effective incorporation of PB nanoparticles was confirmed using diverse instrumentations such as X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). A nitrogen adsorption/desorption study showed that surface area and pore volume increased significantly compared with the starting precursor. Adsorption tests were performed with ¹³³Cs ions to examine adsorption isotherms using both Langmuir and Freundlich isotherms. In addition, adsorption kinetics were also investigated and parameters were calculated. The functionalized porous carbon monolith showed a relatively higher adsorption capacity than that of pristine porous carbon monolith and the bulk PB to most radioactive ions such as ¹³³Cs, ⁸⁵Rb, ¹³⁸Ba, ⁸⁸Sr, ¹⁴⁰Ce, and ²⁰⁵Tl. This material can be used for decontamination in expanded application fields.     

Synthesis of polypyrrole‐modified TiO2 composite adsorbent and its adsorption performance on acid Red G

The adsorption–desorption characteristics of Acid Red G (ARG) on the polypyrrole‐modified TiO₂ (PPy/TiO₂) composite as a novel adsorbent was investigated. PPy/TiO₂ was synthesized via the in‐situ polymerization of pyrrole monomer in the prepared TiO₂ sol solution. Results from X‐ray diffraction and Fourier transform infrared spectra indicated the formation of the PPy/TiO₂ composite. The adsorption experiments showed that the modification of PPy substantially improved the adsorption and regeneration abilities of PPy/TiO₂. The adsorption equilibrium was achieved in a short time of 20 min, and the adsorption kinetics followed the pseudo‐second‐order model. The Langmuir adsorption isotherm was found for PPy/TiO₂, with the maximum adsorption capacity of 179.21 mg/g. The regeneration experiments showed that PPy/TiO₂ could be successfully regenerated by simple alkali‐acid treatment. The adsorption efficiency of the regenerated PPy/TiO₂ adsorbent for ARG was still greater than 90% after regeneration for 10 times. Additionally, the adsorption efficiency of PPy/TiO₂ for the ARG effluent was still higher than 78% after adsorption–desorption for four times. It is expected that the PPy/TiO₂ composite can be considered as a stable adsorbent for the removal of dye. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Enhanced electrosorption capacity for lead ion removal with polypyrrole and air‐plasma activated carbon nanotube composite electrode

Polypyrrole (PPy) and air‐plasma activated carbon nanotube (CNT) composites (P‐CNT‐PPy) prepared via in situ chemical oxidative polymerization are studied to improve the electrosorption capacity of CNT‐based electrodes for the removal of lead ions. For comparison, the PPy prepared on the CNTs without plasma activation is labeled as CNT/PPy. The morphology of the composite was observed by scanning electron microscopy (SEM), and pore structures were studied by N₂ adsorption‐desorption isotherms. The electrochemical capacitance properties of the composite were measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge‐discharge in lead solutions. With plasma‐activation, the specific surface area of the P‐CNT‐PPy composite is larger than that of CNT/PPy. Additionally, the P‐CNT‐PPy composites exhibit excellent electrochemical performance in lead solution, with a higher specific capacitance and smaller charge transfer resistance than that of CNT/PPy. XPS elemental analysis and electrosorption and regeneration results show that the electrosorption and desorption process is reversible under a voltage of 450 mV. The electrosorption kinetics of P‐CNT‐PPy electrodes abide by pseudo‐second‐order model reaction. The lead ion electrosorption experiments agree with the Langmuir model, and the equilibrium electrosorption capacity of the P‐CNT‐PPy electrodes is 3.6 and 1.3 times higher than that of the CNT and CNT/PPy, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41793.     

Adsorption of methylene blue on hemicellulose‐based stimuli‐responsive porous hydrogel

A stimuli‐responsive porous hydrogel was synthesized from wheat straw hemicellulose using CaCO₃ as the porogen, and its application for the removal of methylene blue was studied. The porous structure of the prepared hydrogel was confirmed by SEM analysis. The effects of pH and polyelectrolyte on the swelling of the hydrogels were discussed, and the porous hydrogels showed excellent sensitivity to pH and salt. The deswelling kinetic study indicated that the hydrogels exhibited rapid shrinking in NaCl aqueous solutions. The methylene blue adsorption on the hydrogels was investigated, and the obtained adsorption data was fitted to the pseudo‐first‐order, pseudo‐second‐order and intra‐particle diffusion kinetics models, and the pseudo‐first‐order kinetic model could describe the adsorption process, and the adsorption process of methylene blue on the hydrogels was controlled by external film diffusion. This study reported that the hemicellulose‐based porous hydrogel is promising for water treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41606.     

Nickel(II)‐imprinted monolithic columns for selective nickel recognition

Ni²⁺‐imprinted monolithic column was prepared for the removal of nickel ions from aqueous solutions. N‐Methacryloyl‐L ‐histidine was used as a complexing monomer for Ni²⁺ ions in the preparation of the Ni²⁺‐imprinted monolithic column. The Ni²⁺‐imprinted poly(hydroxyethyl methacrylate‐N‐methacryloyl‐L ‐histidine) (PHEMAH) monolithic column was synthesized by bulk polymerization. The template ion (Ni²⁺) was removed with a 4‐(2‐pyridylazo) resorcinol (PAR):NH₃? NH₄Cl solution. The water‐uptake ratio of the PHEMAH–Ni²⁺ monolith increased compared with PHEMAH because of the formation of nickel‐ion cavities in the polymer structure. The adsorption of Ni²⁺ ions on both the PHEMAH–Ni²⁺ and PHEMAH monoliths were studied. The maximum adsorption capacity was 0.211 mg/g for the PHEMAH–Ni²⁺ monolith. Fe³⁺, Cu²⁺, and Zn²⁺ ions were used as competitive species in the selectivity experiments. The PHEMAH–Ni²⁺ monolithic column was 268.8, 25.5, and 10.4 times more selective than the PHEMAH monolithic column for the Zn²⁺, Cu²⁺, and Fe³⁺ ions, respectively. The PHEMAH–Ni²⁺ monolithic column could be used repeatedly without a decrease in the Ni²⁺ adsorption capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Protein adsorption materials based on conducting polymers: polypyrrole modified with ω‐(N‐pyrrolyl)‐octylthiol

In order to fabricate a new polymer matrix for application in biochips and to understand the mechanism of adsorption of proteins on conducting polymers, we prepared polypyrrole (PPy) functionalized with ω‐(N‐pyrrolyl)‐octylthiol moieties. The chemical structure of the polymer could be controlled by varying the concentration of pyrrole added as the monomer. Initially, ω‐(N‐pyrrolyl)‐octylthiol was self‐assembled into a monolayer on a gold surface. Thereafter, a layer of uniform and smooth PPy was obtained by the chemical copolymerization of pyrrole and the ω‐(N‐pyrrolyl)‐octylthiol. Bovine serum albumin (BSA) adsorption on the polymer was investigated using surface plasmon resonance spectroscopy and cyclic voltammograms. The chemical structure and monomer components of the as‐prepared films were characterized using Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Water contact angle measurements were used to assess the surface wettability of the films throughout the preparative procedure. The kinetics of BSA adsorption onto the polymer could be controlled by varying the copolymer thickness and the pH value of the buffer solutions used. Moreover, the electroactivity was changed upon BSA binding. The results suggest that the new conducting polymer may potentially be applied as a more sensitive and reliable matrix in protein sensors. Copyright © 2011 Society of Chemical Industry     

Self‐assembled polypyrrole film by interfacial polymerization for supercapacitor applications

A facile interfacial synthesis strategy is proposed to synthesize self‐assembled polypyrrole (PPy) free‐standing films for electrochemical capacitors with the assistance of surfactants. The chemical structure of the obtained samples is characterized by Fourier transform infrared. The morphologies of the samples are studied by scanning electron microscope. The results show that the prepared PPy films own highly porous structures using Tween80 as a surfactant, while the synthesized PPy films have vesicular structures by adding Span80 as a surfactant. Furthermore, lowering polymerization temperature makes PPy films have smaller and more pores or vesicles. The PPy films prepared at 0°C with Tween80 as a surfactant possess a high specific capacitance of 261 F g^?1 at 25 mV s^?1 as well as retain 75% of the initial specific capacitance value after 1000 cycles. The good electrochemical properties can be attributed to the highly porous structural advantage of the PPy films caused by Tween80. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41615.     

Highly efficient and reversible CO2 capture by tunable anion‐functionalized macro‐porous resins

Anion functionalized strategy has been proposed for the synthesis of macro‐porous resins [IRA‐900][An] through the neutral reaction of the basic resin [IRA‐900][OH] with the corresponding donors. Combining CO₂ adsorption results and FT‐IR, solid‐state ¹³C NMR characterization as well as quantum chemical calculations, chemical adsorption mechanism was verified and tunable capture of CO₂ was realized. Among them, the anion functionalized resin [IRA‐900][Triz] exhibits an extremely high adsorption capacity (4.02 mmol g^?1 at 25°C, 0.15 bar), outperforming many other good adsorbents. Finally, we discuss the thermostability and recycling stability of [IRA‐900][Triz], which shows a great potential in the industrial capture of CO₂. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3008–3015, 2017     

Surface DEAE groups facilitate protein transport on polymer chains in DEAE‐modified‐and‐DEAE‐dextran‐grafted resins

Sepharose FF was modified with diethylaminoethyl‐dextran (DEAE‐dextran, DexD) and/or DEAE (D) to fabricate three types of ion exchangers FF‐DexD (grafting‐ligand resin), FF‐D (surface‐ligand resin), and FF‐D‐DexD (mixed‐ligand resin), for protein adsorption equilibria and kinetics study. It was found that both adsorption capacity and uptake rate (effective diffusivity, D_e) were significantly enhanced by grafting DEAE‐dextran. Notably, the D_e values on FF‐DexD and FF‐D‐DexD (D_e/D₀ > 1.4) were six times greater than those on FF‐D (D_e/D₀ < 0.3). More importantly, the increase of surface‐ligand density greatly enhanced uptake kinetics on FF‐D‐DexD. The results indicate that the surface ligands assisted the transport of bound proteins on polymer chains in the mixed‐ligand resins. That is, surface ligands worked as “transfer stations” between two neighboring chains, resulting in enhanced transport of bound proteins on chains. The research thus disclosed the unique role of surface ligands in facilitating protein uptake kinetics onto polymer‐grafted ion‐exchangers. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3812–3819, 2016     

Novel porous organic triazine‐based polyimide with high nitrogen levels for highly efficient removal of Ni(II) from aqueous solution

In this study, a porous organic triazine‐based polyimide (PPI network) was prepared from 2,4,6‐tris(hydrazino)‐s‐triazine and 3,4,9,10‐perylenetetracarboxylic dianhydride. TGA, Fourier transform infrared spectroscopy, field emission SEM, XRD and a nitrogen sorption study confirmed the PPI network structure. Then, the synthesized PPI network was used to evaluate Ni²⁺ ion removal from aqueous solution and the effective parameters on adsorption functions of Ni²⁺ ions such as initial concentration, contact time and pH of the solution in batch adsorption experiments was studied. The results showed that the maximum adsorption capacity (q_m) of Ni²⁺ ions was 36.1 mg g^?1 in only 30 min with a pH of 7. The kinetics and adsorption isotherm were identified to be better fitted by the pseudo‐second‐order model and the Langmuir model, respectively. Based on the results, the proposed adsorbent has good potential for removing Ni²⁺ ions from aqueous solutions. © 2019 Society of Chemical Industry     

Absorbency and adsorption of poly(acrylic acid‐co‐acrylamide) hydrogel

Poly(acrylic acid‐co‐acrylamide) (PAAAM) hydrogels have been prepared from partly neutralized acrylic acid (AA) and acrylamide (AM) by solution polymerization, and their absorbency and adsorption in both CuCl₂ and FeCl₃ solutions have been investigated. PAAAM hydrogels and their complexes with Cu²⁺ or Fe³⁺ have been characterized by FTIR. The absorbency of PAAAM in both CuCl₂ and FeCl₃ solutions increases initially and then decreases as the absorbing time increases. The adsorption of PAAAM in both CuCl₂ and FeCl₃ solutions can be described by the pseudo‐second order chemisorption kinetics proposed by Ho and McKay, and the equilibrium uptake of Cu²⁺ on PAAAM can well be fit with the Langmuir adsorption isotherm. However, the equilibrium uptake of Fe³⁺ on PAAAM increases as the initial Fe³⁺ concentration increases for Fe³⁺ concentration smaller than 5.625 × 10^?3 mol/L, and then decreases with Fe³⁺ concentration. The largest uptakes for Cu²⁺ and Fe³⁺ are 247 and 173 mg/g, respectively. The results also show that the uptake of Cu²⁺ and Fe³⁺ on PAAAM increases remarkably when pH of the solution is changed from 2.3 to 4.2 and from 1.0 and 2.1, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Development of a fixed‐bed column with cellulose/chitin beads to remove heavy‐metal ions

Environmental friendly cellulose/chitin beads, having relatively high mechanical properties, were successfully prepared from a blend of cellulose and chitin in 6 wt % NaOH/5 wt % thiourea aqueous solution by coagulating with 5% H₂SO₄ aqueous solution. The ability of the beads to adsorb Pb²⁺ in an aqueous solution was measured with a fixed‐bed column. The effects of important parameters, to design an adsorption column of the cellulose/chitin beads for fixed‐bed columns, were investigated. The breakthrough curves for the adsorption behavior indicated that the column performance was improved with decreasing initial lead concentration, ionic strength, flow velocity or bead size, as well as increasing pH dependence and bed height. Column studies showed that constants, calculated from the experimental data, and the Bed Depth Service Time (BDST) model had a good correlation. The columns were easily regenerated by treating with 0.1 mol/L HCl aqueous solution after the adsorption of metals, providing a simple and economical method for removal and recovery of heavy metals. After four adsorption–desorption cycles, the efficiency of column for the removal of lead was not significantly reduced (not more than 5%). It is shown that heavy‐metal biosorption processes in fixed‐bed columns could give a broad range of potential industrial applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 684–691, 2004     

CO2 sorption performance by aminosilane functionalized spheres prepared via co‐condensation and post‐synthesis methods

Amine functionalized silica microspheres were synthesised via a modified Stöber reaction for carbon dioxide (CO₂) adsorption. A number of adsorbents were synthesized by co‐condensation and post synthesis immobilization of amines on porous silica spheres. CO₂ adsorption studies were carried out on a fixed bed gas adsorption rig with online mass spectrometry. Amine co‐condensed silica spheres were found to adsorb up to 66 mg CO₂ g^?1 solid in a 0.15 atm CO₂ stream at 35°C. Simple post‐synthesis addition of aminopropyltriethoxysilane to amine co‐condensed silica was found to significantly increase the uptake of CO₂ to 211 mg CO₂ g^?1 under similar conditions, with CO₂ desorption commencing at temperatures as low as 60°C. The optimum temperature for adsorption was found to be 35°C. This work presents a CO₂ adsorbent prepared via a simple synthesis method, with a high CO₂ adsorption capacity and favorable CO₂ adsorption/desorption performance under simulated flue gas conditions. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2825–2832, 2016     

Removal of methylene blue (aq) using untreated and acid‐treated eucalyptus leaves and GA‐ANN modelling

In the present batch study, eucalyptus leaves (EUL), H₂SO₄‐treated eucalyptus leaves (SEUL), and H₃PO₄‐treated eucalyptus leaves (PEUL) are used as bio‐adsorbents for the removal of methylene blue (MB). The bio‐adsorption is executed to inspect the results of the variation between different experimental variables such as pH (2–10), adsorbent dose (1–10 g/L), contact time (5–360 min), and temperature (298–318 K) on the bio‐adsorption of MB. The Langmuir isotherm (R² = 0.99) fitted adequately to the bio‐adsorption data for the initial MB concentrations of 10–300 mg/L. It is also necessary to mention that the MB bio‐adsorption occurred in the order of a monolayer on the EUL, SEUL, and PEUL. The bio‐adsorption kinetics have been fitted by the pseudo‐second‐order model (R² ≥ 0.99) for various MB concentrations. The maximum bio‐adsorption capacity was 194.34 mg/g and was achieved for the H₃PO₄‐treated eucalyptus leaves (PEUL). These results showed that EUL, SEUL, and PEUL may be utilized as a favourable low‐cost bio‐adsorbent to eliminate MB from aqueous solutions. With safe disposal methods in mind, this investigation has revealed the eco‐friendliness of the bio‐adsorbents. A prediction of the removal percentage of methylene blue using a genetic algorithm (GA) from the data collected from the experiment has also been tested. The results related to the prediction using the GA‐ANN are accurate.     

Ion‐imprinted PHEMA based monolith for the removal of Fe3+ ions from aqueous solutions

Molecular recognition based Fe³⁺ imprinted monolith was prepared for selective removal of Fe³⁺ ions from aqueous solutions. The precomplexation was achieved by the coordination of Fe³⁺ ions with N‐methacryloyl‐(L )‐cysteine methyl ester (MAC) to form the complex monomer (MAC‐Fe³⁺). The polymerization step was then carried out in the presence of MAC‐Fe³⁺ complex and hydroxyethyl methacrylate (HEMA) monomer by bulk polymerization to constitude a Fe³⁺‐imprinted polymer (PHEMAC‐Fe³⁺). The specific surface area of PHEMAC‐Fe³⁺ monolith was found to be 35.2 m²/g, with a swelling ratio of 60.2% after the template was removed from the monolith by 0.1M EDTA solution. The maximum adsorption capacity of PHEMAC‐Fe³⁺ monolith for Fe³⁺ ion was 0.76 mg/g. The adsorption behavior of the monolith has been successfully described by the Langmuir isotherm. It was determined that the relative selectivity of PHEMAC‐Fe³⁺ monolith was 59.7 and 37.0 times greater than that of the nonimprinted PHEMAC monolith as compared with the Cd²⁺ and Ni²⁺ ions, respectively. The PHEMAC‐Fe³⁺ monolith was recovered and reused many times without any significant decrease in its adsorption capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Microporous gel electrolyte for quasi‐solid‐state dye‐sensitized solar cell

The extension of electrocatalytic reaction of I^?/I₃^? from counter electrode/gel electrolyte interface to gel electrolyte can significantly enhance the redox kinetics and therefore conversion efficiency of dye‐sensitized solar cells. Microporous gel electrolyte from polypyrrole integrated poly(hydroxyethyl methacrylate/cetytrimethylammonium bromide) [PPy‐integrated poly (HEMA/CTAB)] is successfully synthesized by in‐situ polymerization of pyrrole monomers in three‐dimensional framework of porous poly(HEMA/CTAB) matrix. An ionic conductivity of 12.72 mS cm^?1 and activation energy of 8.65 kJ mol^?1 are obtained from PPy‐integrated poly(HEMA/CTAB) gel electrolyte. Tafel polarization and electrochemical impedance spectroscopy are employed to characterize the electrocatalytic behaviors of the gel electrolytes. The resultant quasi‐solid‐state dye‐sensitized solar cell shows a light‐to‐electrical conversion efficiency of 6.68%. POLYM. ENG. SCI., 54:2531–2535, 2014. © 2013 Society of Plastics Engineers     

Antibody purification using porous metal–chelated monolithic columns

A novel monolithic material was developed to obtain efficient and cost‐effective purification of IgG from human plasma. The porous monolith was obtained by bulk polymerization in a glass tube of 2‐hydroxyethyl methacrylate (HEMA) and N‐methacryloyl‐(L )‐histidine methyl ester (MAH). The poly(HEMA‐MAH) monolith had a specific surface area of 214.6 m²/g and was characterized by swelling studies, porosity measurement, FTIR, scanning electron microscopy, and elemental analysis. Then the monolith was loaded with Cu²⁺ ions to form the metal chelate. Poly(HEMA‐MAH) monolith with a swelling ratio of 74% and containing 20.9 μmol MAH/g was used in the adsorption/desorption of IgG from aqueous solutions and human plasma. The maximum adsorption of IgG from an aqueous solution in phosphate buffer was 10.8 mg/g at pH 7.0. Higher adsorption was obtained from human plasma (up to 104.2 mg/g), with a purity of 94.1%. It was observed that IgG could be repeatedly adsorbed and desorbed with the poly(HEMA‐MAH) monolith without significant loss of adsorption capacity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 395–404, 2006     

Ion‐exchange adsorption of calcium ions from water and geothermal water with modified zeolite A

The modified zeolite A was prepared by a two‐step crystallization method to remove scale‐forming cations from water and geothermal water. The adsorption kinetics, mechanism and thermodynamics were studied. The calcium ion adsorption capacity of the modified zeolite A was 129.3 mg/g (1 mg/g = 10^?3 kg/kg) at 298 K. The adsorption rate was fitted well with pseudo‐second‐order rate model. The adsorption process was controlled by film diffusion at the calcium ion concentration less than 250 mg/L (1 mg/L = 10^?3 kg/m³), and it was controlled by intraparticle diffusion at the concentration larger than 250 mg/L. The calculated mass‐transfer coefficient ranged from 2.23 × 10^?5 to 2.80 × 10^?4cm/s (1 cm/s = 10^?2m/s). Dubinin–Astakhov isotherm model could appropriately describe the adsorption thermodynamic properties when combined with Langmuir model. The adsorption process included not only ion exchange but also complexation between calcium and hydroxyl ions. The adsorption was spontaneous and endothermal. The high adsorption capacity indicates that the modified zeolite A is a suitable adsorption material for scale removal from aqueous solution. © 2014 American Institute of Chemical Engineers AIChE J, 61: 640–654, 2015     

Investigation of α‐iron oxide‐coated polymeric nanocomposites capacity for efficient heavy metal removal from aqueous solution

In the present study, PS@α‐Fe₂O₃ nanocomposites were prepared by chemical microemulsion polymerization approach and the ability of magnetic beads to remove Cu(II) ions from aqueous solutions in a batch media was investigated. Various physico‐chemical parameters such as pH, initial metal ion concentration, temperature, and equilibrium contact time were also studied. Adsorption mechanism of Cu²⁺ ions onto magnetic polymeric adsorbents has been investigated using Langmuir, Freundlich, Sips and Redlich–Petersen isotherms. The results demonstrated that the PS@α‐Fe₂O₃ nanocomposite is an effective adsorbent for Cu²⁺ ions removal. The Sips adsorption isotherm model (R² > 0.99) was more in consistence with the adsorption isotherm data of Cu(II) ions compared to other models and the maximum adsorbed amount of copper was 34.25 mg/g. The adsorption kinetics well fitted to a pseudo second‐order kinetic model. The thermodynamic parameters (ΔH°, ΔS°, and ΔG°) were calculated from the temperature dependent sorption isotherms, and the results suggested that copper adsorption was a spontaneous and exothermic process. POLYM. ENG. SCI., 55:2735–2742, 2015. © 2015 Society of Plastics Engineers     

CuBr2‐induced charge screening on photoactive nanocolloidal polypyrrole:poly(styrene sulfonate) composite multilayer thin‐film counter electrodes for high‐efficiency dye‐sensitized solar cells

Nanocolloidal polypyrrole (PPy):poly(styrene sulfonate) (PSS) particles were synthesized by chemical oxidative polymerization using 15 wt% of PSS. The highly processable polymer composite (PPy:PSS) was spin‐coated at 4000 rpm on fluorine‐doped tin oxide glass and subsequently employed as a counter electrode (CE) for dye‐sensitized solar cells (DSCs). PPy:PSS multilayer (one, three, five) CEs were treated with CuBr₂ salt, which enhances the efficiency of the DSCs. Optical studies reveal that a bulkier counterion hinders interchain interactions of PPy which on salt treatment shows a moderate redshift in absorption maxima. Salt‐treated PPy:PSS films exhibit lower charge transfer resistance, higher surface roughness and better catalytic performance for the reduction of I₃^?, when compared with untreated films. The improved catalytic performance of salt‐treated PPy:PSS multilayer films is attributed to charge screening and conformational change of PPy, along with the removal of excess PSS. Under standard AM 1.5 sunlight illumination, salt treatment is shown to boost the efficiency of multilayer PPy:PSS composite film‐based DSCs, leading to enhanced power conversion efficiency of 6.18, 6.33 and 6.37% for one, three and five layers, respectively. These values are significantly higher (ca 50%) than those for corresponding devices without CuBr₂ salt treatment (3.48, 2.90 and 2.01%, respectively). © 2016 Society of Chemical Industry