Carbon Nanotube Membranes in Water Treatment Applications

Carbon nanotube (CNT)-based membranes combine the promising properties of CNTs with the advantages of membrane separation technologies, offering enhanced membrane performance in terms of permeability and selectivity. This review looks at the existing membrane architectures based on CNTs and their main advantages and disadvantages for water treatment applications. The different types of CNT-based membranes that are reported in the literature are highlighted, as well as their corresponding fabrication methods. Available methodologies for tailoring the final membrane properties and behavior are thoroughly discussed, making special emphasis in chemical modification of the CNT surface. Finally, the most common applications of CNT-based membranes in water treatment are reviewed, including seawater or brine desalination, oil-water separation, removal of heavy metals, and organic pollutants. The main limitations and perspectives of CNT-based membranes are also briefly outlined

Covalent functionalization of N-doped graphene by N-alkylation

[EN] Nitrogen doped graphene was modified by N-alkylation using a combination of phase transfer catalysis and microwave irradiation. The resulting derivatives of N-doped graphene were analysed showing that the bandgap of the material varied depending on the alkylation agent used.Financial support from MINECO (Spain) (CTQ2013-48252-P and CTQ2012-32315), Junta de Comunidades de Castilla-La Mancha (PEII-2014-014-P) and Generalidad Valenciana (Prometeo 13/19) is gratefully acknowledged. M.B. thanks the MINECO for a doctoral FPI grant.Barrejon, M.; Primo Arnau, AM.; Gomez-Escalonilla, M.; Fierro, JLG.; García Gómez, H.; Langa, F. (2015). Covalent functionalization of N-doped graphene by N-alkylation. Chemical Communications. 51(95):16916-16919. https://doi.org/10.1039/c5cc06285cS16916169195195Wang, H., Maiyalagan, T., & Wang, X. (2012). Review on Recent Progress in Nitrogen-Doped Graphene: Synthesis, Characterization, and Its Potential Applications. ACS Catalysis, 2(5), 781-794. doi:10.1021/cs200652yNavalon, S., Dhakshinamoorthy, A., Alvaro, M., & Garcia, H. (2014). Carbocatalysis by Graphene-Based Materials. Chemical Reviews, 114(12), 6179-6212. doi:10.1021/cr4007347Rodríguez-Pérez, L., Herranz, M. Á., & Martín, N. (2013). The chemistry of pristine graphene. Chemical Communications, 49(36), 3721. doi:10.1039/c3cc38950bWei, D., Liu, Y., Wang, Y., Zhang, H., Huang, L., & Yu, G. (2009). Synthesis of N-Doped Graphene by Chemical Vapor Deposition and Its Electrical Properties. Nano Letters, 9(5), 1752-1758. doi:10.1021/nl803279tLee, W. J., Maiti, U. N., Lee, J. M., Lim, J., Han, T. H., & Kim, S. O. (2014). Nitrogen-doped carbon nanotubes and graphene composite structures for energy and catalytic applications. Chemical Communications, 50(52), 6818. doi:10.1039/c4cc00146jPrimo, A., Atienzar, P., Sanchez, E., Delgado, J. M., & García, H. (2012). From biomass wastes to large-area, high-quality, N-doped graphene: catalyst-free carbonization of chitosan coatings on arbitrary substrates. Chemical Communications, 48(74), 9254. doi:10.1039/c2cc34978gPrimo, A., Sánchez, E., Delgado, J. M., & García, H. (2014). High-yield production of N-doped graphitic platelets by aqueous exfoliation of pyrolyzed chitosan. Carbon, 68, 777-783. doi:10.1016/j.carbon.2013.11.068Wang, X., Sun, G., Routh, P., Kim, D.-H., Huang, W., & Chen, P. (2014). Heteroatom-doped graphene materials: syntheses, properties and applications. Chem. Soc. Rev., 43(20), 7067-7098. doi:10.1039/c4cs00141aWu, M., Cao, C., & Jiang, J. Z. (2010). Light non-metallic atom (B, N, O and F)-doped graphene: a first-principles study. Nanotechnology, 21(50), 505202. doi:10.1088/0957-4484/21/50/505202Rani, P., & Jindal, V. K. (2013). Designing band gap of graphene by B and N dopant atoms. RSC Adv., 3(3), 802-812. doi:10.1039/c2ra22664bLatorre-Sánchez, M., Primo, A., Atienzar, P., Forneli, A., & García, H. (2014). p-n Heterojunction of Doped Graphene Films Obtained by Pyrolysis of Biomass Precursors. Small, 11(8), 970-975. doi:10.1002/smll.201402278Gupta, M., Gaur, N., Kumar, P., Singh, S., Jaiswal, N. K., & Kondekar, P. N. (2015). Tailoring the electronic properties of a Z-shaped graphene field effect transistor via B/N doping. Physics Letters A, 379(7), 710-718. doi:10.1016/j.physleta.2014.12.046Kim, H. S., Kim, H. S., Kim, S. S., & Kim, Y.-H. (2014). Atomistic mechanisms of codoping-induced p- to n-type conversion in nitrogen-doped graphene. Nanoscale, 6(24), 14911-14918. doi:10.1039/c4nr05024jShirakawa, S., & Maruoka, K. (2013). Recent Developments in Asymmetric Phase-Transfer Reactions. Angewandte Chemie International Edition, 52(16), 4312-4348. doi:10.1002/anie.201206835Langa, F., & la Cruz, P. (2007). Microwave Irradiation: An Important Tool to Functionalize Fullerenes and Carbon Nanotubes. Combinatorial Chemistry & High Throughput Screening, 10(9), 766-782. doi:10.2174/138620707783018487Langa, F., de la Cruz, P., Espı́ldora, E., Garcı́a, J. J., Pérez, M. C., & de la Hoz, A. (2000). Fullerene chemistry under microwave irradiation. Carbon, 38(11-12), 1641-1646. doi:10.1016/s0008-6223(99)00284-5Kappe, C. O. (2004). Controlled Microwave Heating in Modern Organic Synthesis. Angewandte Chemie International Edition, 43(46), 6250-6284. doi:10.1002/anie.200400655Keglevich, G., Grün, A., & Bálint, E. (2013). Microwave Irradiation and Phase Transfer Catalysis in C-, O- and N-Alkylation Reactions. Current Organic Synthesis, 10(5), 751-763. doi:10.2174/1570179411310050006Ni, Z. H., Ponomarenko, L. A., Nair, R. R., Yang, R., Anissimova, S., Grigorieva, I. V., … Geim, A. K. (2010). On Resonant Scatterers As a Factor Limiting Carrier Mobility in Graphene. Nano Letters, 10(10), 3868-3872. doi:10.1021/nl101399rChang, C.-K., Kataria, S., Kuo, C.-C., Ganguly, A., Wang, B.-Y., Hwang, J.-Y., … Chen, K.-H. (2013). Band Gap Engineering of Chemical Vapor Deposited Graphene by in Situ BN Doping. ACS Nano, 7(2), 1333-1341. doi:10.1021/nn3049158Cuong, T. V., Pham, V. H., Tran, Q. T., Hahn, S. H., Chung, J. S., Shin, E. W., & Kim, E. J. (2010). Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide. Materials Letters, 64(3), 399-401. doi:10.1016/j.matlet.2009.11.029Koh, Y. K., Bae, M.-H., Cahill, D. G., & Pop, E. (2010). Reliably Counting Atomic Planes of Few-Layer Graphene (n > 4). ACS Nano, 5(1), 269-274. doi:10.1021/nn102658aReina, A., Jia, X., Ho, J., Nezich, D., Son, H., Bulovic, V., … Kong, J. (2009). Large Area, Few-Layer Graphene Films on Arbitrary Substrates by Chemical Vapor Deposition. Nano Letters, 9(1), 30-35. doi:10.1021/nl801827vPan, C.-T., Hinks, J. A., Ramasse, Q. M., Greaves, G., Bangert, U., Donnelly, S. E., & Haigh, S. J. (2014). In-situ observation and atomic resolution imaging of the ion irradiation induced amorphisation of graphene. Scientific Reports, 4(1). doi:10.1038/srep06334Lu, Y.-F., Lo, S.-T., Lin, J.-C., Zhang, W., Lu, J.-Y., Liu, F.-H., … Li, L.-J. (2013). Nitrogen-Doped Graphene Sheets Grown by Chemical Vapor Deposition: Synthesis and Influence of Nitrogen Impurities on Carrier Transport. ACS Nano, 7(8), 6522-6532. doi:10.1021/nn402102yTauc, J., Grigorovici, R., & Vancu, A. (1966). Optical Properties and Electronic Structure of Amorphous Germanium. physica status solidi (b), 15(2), 627-637. doi:10.1002/pssb.1966015022

Carbon Nanostructures in Rotaxane Architectures

Considerable research efforts have been devoted to the development of rotaxanes and the study of their unique dynamic properties. This minireview provides an overview of the main advances that have been realized in rotaxane architectures involving different types of carbon nanostructures. In particular, rotaxanes based on fullerenes and carbon nanotubes will be discussed

Synthesis, characterization and photoinduced charge separation of carbon nanohorn-oligothienylenevinylene hybrids

[EN] The covalent coupling between oligo(thienylenevinylenes) (nTVs) and carbon nanohorns (CNHs) has been investigated. The resulting nanohybrids have been characterized by a combination of several techniques, including thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy. The photophysical properties of the new hybrids were investigated by steady-state and time-resolved spectroscopic techniques. A transient signal characterized by two kinetic regimes, one short decay within 0.5 mu s corresponding to around 80% of the total signal and another much longer-lived decay of 10 ms, has been detected. The transient absorption spectra are characterized by a continuous absorption that increases in intensity towards shorter wavelengths, with a maximum at 430 nm. These transient signals have been assigned to the chargeseparated state delocalized on CNHs based on the quenching behavior and by comparison with the photophysical properties of nTV in the absence and presence of quenchers. The photophysical behavior of covalent nTV-CNH conjugates with microsecond transients due to electrons and holes on CNHs contrasts with the absence of any transient for analogous nTV-C-60 conjugates, for which charge separation was not observed at timescales longer than nanoseconds. The photochemical behavior of CNHs is believed to derive from the amphoteric (electron donor and acceptor) properties of CNHs and from the larger number of carbon atoms (efficient delocalization) in CNHs compared with C-60.Financial support from the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, CTQ2011-26455, CTQ201232315 and CTQ2013-48252-P) and Junta de Comunidades de Castilla-La Mancha (PEII-2014-014-P) is gratefully acknowledged. P. A. also thanks the Spanish Ministry of Science and Innovation for a Ramon y Cajal research associate contract (RYC-2012-10702) and the Generalitat Valenciana for the grant GV-2014/101. M. B. thanks the MINECO for a doctoral FPI grant. We also acknowledge M. C. Cuquerella for performing the femtosecond spectroscopy measurements.Vizuete, M.; Gomez-Escalonilla, MJ.; Barrejon, M.; Fierro, JL.; Zhang, M.; Yudasaka, M.; Iijima, S.... (2016). Synthesis, characterization and photoinduced charge separation of carbon nanohorn-oligothienylenevinylene hybrids. Physical Chemistry Chemical Physics. 18(3):1828-1837. https://doi.org/10.1039/c5cp05734eS18281837183Aich, N., Plazas-Tuttle, J., Lead, J. R., & Saleh, N. B. (2014). A critical review of nanohybrids: synthesis, applications and environmental implications. Environmental Chemistry, 11(6), 609. doi:10.1071/en14127De Volder, M. F. L., Tawfick, S. H., Baughman, R. H., & Hart, A. J. (2013). Carbon Nanotubes: Present and Future Commercial Applications. Science, 339(6119), 535-539. doi:10.1126/science.1222453Schnorr, J. M., & Swager, T. M. (2011). Emerging Applications of Carbon Nanotubes†. Chemistry of Materials, 23(3), 646-657. doi:10.1021/cm102406hKarousis, N., Tagmatarchis, N., & Tasis, D. (2010). Current Progress on the Chemical Modification of Carbon Nanotubes. Chemical Reviews, 110(9), 5366-5397. doi:10.1021/cr100018gCarbon Nanotubes and Related Structures: Synthesis, Characterization, Functionalization, and Applications, ed. D. M. Guldi and N. Martín, Wiley-VCH Verlag GmbH & Co. Kga, 2010Georgakilas, V., Perman, J. A., Tucek, J., & Zboril, R. (2015). Broad Family of Carbon Nanoallotropes: Classification, Chemistry, and Applications of Fullerenes, Carbon Dots, Nanotubes, Graphene, Nanodiamonds, and Combined Superstructures. Chemical Reviews, 115(11), 4744-4822. doi:10.1021/cr500304fBottari, G., de la Torre, G., & Torres, T. (2015). Phthalocyanine–Nanocarbon Ensembles: From Discrete Molecular and Supramolecular Systems to Hybrid Nanomaterials. Accounts of Chemical Research, 48(4), 900-910. doi:10.1021/ar5004384Hasobe, T. (2013). Porphyrin-Based Supramolecular Nanoarchitectures for Solar Energy Conversion. The Journal of Physical Chemistry Letters, 4(11), 1771-1780. doi:10.1021/jz4005152Roncali, J. (2000). Oligothienylenevinylenes as a New Class of Multinanometer Linear π-Conjugated Systems for Micro- and Nanoelectronics. Accounts of Chemical Research, 33(3), 147-156. doi:10.1021/ar990023mJestin, I., Frère, P., Mercier, N., Levillain, E., Stievenard, D., & Roncali, J. (1998). Synthesis and Characterization of the Electronic and Electrochemical Properties of Thienylenevinylene Oligomers with Multinanometer Dimensions. Journal of the American Chemical Society, 120(32), 8150-8158. doi:10.1021/ja980603zOswald, F., Shafiqul Islam, D.-M., El-Khouly, M. E., Araki, Y., Caballero, R., de la Cruz, P., … Langa, F. (2014). Photoinduced electron transfer of zinc porphyrin–oligo(thienylenevinylene)–fullerene[60] triads; thienylenevinylenes as efficient molecular wires. Phys. Chem. Chem. Phys., 16(6), 2443-2451. doi:10.1039/c3cp54280gOswald, F., Islam, D.-M. S., Araki, Y., Troiani, V., de la Cruz, P., Moreno, A., … Langa, F. (2007). Synthesis and Photoinduced Intramolecular Processes of Fulleropyrrolidine–Oligothienylenevinylene–Ferrocene Triads. Chemistry - A European Journal, 13(14), 3924-3933. doi:10.1002/chem.200601889Oswald, F., Islam, D.-M. S., Araki, Y., Troiani, V., Caballero, R., Cruz, P. de la, … Langa, F. (2007). High effectiveness of oligothienylenevinylene as molecular wires in Zn-porphyrin and C60 connected systems. Chemical Communications, (43), 4498. doi:10.1039/b711194kApperloo, J. J., Martineau, C., van Hal, P. A., Roncali, J., & Janssen, R. A. J. (2002). Intra- and Intermolecular Photoinduced Energy and Electron Transfer between Oligothienylenevinylenes andN-Methylfulleropyrrolidine. The Journal of Physical Chemistry A, 106(1), 21-31. doi:10.1021/jp012936fLiu, Y., Zhou, J., Zhang, X., Liu, Z., Wan, X., Tian, J., … Chen, Y. (2009). Synthesis, characterization and optical limiting property of covalently oligothiophene-functionalized graphene material. Carbon, 47(13), 3113-3121. doi:10.1016/j.carbon.2009.07.027Jestin, I., Frère, P., Blanchard, P., & Roncali, J. (1998). Extended Thienylenevinylene Oligomers as Highly Efficient Molecular Wires. Angewandte Chemie International Edition, 37(7), 942-945. doi:10.1002/(sici)1521-3773(19980420)37:73.0.co;2-8Zhu, S., & Xu, G. (2010). Single-walled carbon nanohorns and their applications. Nanoscale, 2(12), 2538. doi:10.1039/c0nr00387ePramoda, K., Moses, K., Ikram, M., Vasu, K., Govindaraj, A., & Rao, C. N. R. (2013). Synthesis, Characterization and Properties of Single-Walled Carbon Nanohorns. Journal of Cluster Science, 25(1), 173-188. doi:10.1007/s10876-013-0652-6G. Pagona and N.Tagmatarchis, in Advances in Carbon Nanomaterials: Science and Applications: Carbon Nanohorns Chemical Functionalization, ed. N. Tagmatarchis, Pan Stanford Publishing, 1st edn, 2012, ch. 6, pp. 239–268Cataldo, S., Salice, P., Menna, E., & Pignataro, B. (2012). Carbon nanotubes and organic solar cells. Energy Environ. Sci., 5(3), 5919-5940. doi:10.1039/c1ee02276hPagona, G., Zervaki, G. E., Sandanayaka, A. S. D., Ito, O., Charalambidis, G., Hasobe, T., … Tagmatarchis, N. (2012). Carbon Nanohorn–Porphyrin Dimer Hybrid Material for Enhancing Light-Energy Conversion. The Journal of Physical Chemistry C, 116(17), 9439-9449. doi:10.1021/jp302178qCosta, R. D., Feihl, S., Kahnt, A., Gambhir, S., Officer, D. L., Wallace, G. G., … Guldi, D. M. (2013). Carbon Nanohorns as Integrative Materials for Efficient Dye-Sensitized Solar Cells. Advanced Materials, 25(45), 6513-6518. doi:10.1002/adma.201301527Zhang, Q., Huang, J.-Q., Qian, W.-Z., Zhang, Y.-Y., & Wei, F. (2013). The Road for Nanomaterials Industry: A Review of Carbon Nanotube Production, Post-Treatment, and Bulk Applications for Composites and Energy Storage. Small, 9(8), 1237-1265. doi:10.1002/smll.201203252Lodermeyer, F., Costa, R. D., Casillas, R., Kohler, F. T. U., Wasserscheid, P., Prato, M., & Guldi, D. M. (2015). Carbon nanohorn-based electrolyte for dye-sensitized solar cells. Energy & Environmental Science, 8(1), 241-246. doi:10.1039/c4ee02037eVizuete, M., Gómez-Escalonilla, M. J., Fierro, J. L. G., Sandanayaka, A. S. D., Hasobe, T., Yudasaka, M., … Langa, F. (2010). A Carbon NanohornPorphyrin Supramolecular Assembly for Photoinduced Electron-Transfer Processes. Chemistry - A European Journal, 16(35), 10752-10763. doi:10.1002/chem.201000299Vizuete, M., Gómez-Escalonilla, M. J., Fierro, J. L. G., Yudasaka, M., Iijima, S., Vartanian, M., … Langa, F. (2011). A soluble hybrid material combining carbon nanohorns and C60. Chemical Communications, 47(48), 12771. doi:10.1039/c1cc15446jPagona, G., Katerinopoulos, H. E., & Tagmatarchis, N. (2011). Synthesis, characterization, and photophysical properties of a carbon nanohorn–coumarin hybrid material. Chemical Physics Letters, 516(1-3), 76-81. doi:10.1016/j.cplett.2011.09.055Pagona, G., Rotas, G., Petsalakis, I. D., Theodorakopoulos, G., Fan, J., Maigné, A., … Tagmatarchis, N. (2007). Soluble Functionalized Carbon Nanohorns. Journal of Nanoscience and Nanotechnology, 7(10), 3468-3472. doi:10.1166/jnn.2007.821Pagona, G., Karousis, N., & Tagmatarchis, N. (2008). Aryl diazonium functionalization of carbon nanohorns. Carbon, 46(4), 604-610. doi:10.1016/j.carbon.2008.01.007Urbani, M., Pelado, B., de la Cruz, P., Yamanaka, K., Ito, O., & Langa, F. (2011). Synthesis and Photoinduced Energy‐ and Electron‐Transfer Processes of C 60 –Oligothienylenevinylene–C 70 Dumbbell Compounds. Chemistry – A European Journal, 17(19), 5432-5444. doi:10.1002/chem.201002318Cioffi, C., Campidelli, S., Brunetti, F. G., Meneghetti, M., & Prato, M. (2006). Functionalisation of carbon nanohorns. Chemical Communications, (20), 2129. doi:10.1039/b601176dUtsumi, S., Honda, H., Hattori, Y., Kanoh, H., Takahashi, K., Sakai, H., … Kaneko, K. (2007). Direct Evidence on C−C Single Bonding in Single-Wall Carbon Nanohorn Aggregates. The Journal of Physical Chemistry C, 111(15), 5572-5575. doi:10.1021/jp071273kFantini, C., Pimenta, M. A., & Strano, M. S. (2008). Two-Phonon Combination Raman Modes in Covalently Functionalized Single-Wall Carbon Nanotubes. The Journal of Physical Chemistry C, 112(34), 13150-13155. doi:10.1021/jp803855zVoggu, R., Rout, C. S., Franklin, A. D., Fisher, T. S., & Rao, C. N. R. (2008). Extraordinary Sensitivity of the Electronic Structure and Properties of Single-Walled Carbon Nanotubes to Molecular Charge-Transfer. The Journal of Physical Chemistry C, 112(34), 13053-13056. doi:10.1021/jp805136eDo Nascimento, G. M., Hou, T., Kim, Y. A., Muramatsu, H., Hayashi, T., Endo, M., … Dresselhaus, M. S. (2011). Behavior of the high frequency Raman modes of double-wall carbon nanotubes after doping with bromine or iodine vapors. Carbon, 49(11), 3585-3596. doi:10.1016/j.carbon.2011.04.061Mevellec, J.-Y., Bergeret, C., Cousseau, J., Buisson, J.-P., Ewels, C. P., & Lefrant, S. (2011). Tuning the Raman Resonance Behavior of Single-Walled Carbon Nanotubes via Covalent Functionalization. Journal of the American Chemical Society, 133(42), 16938-16946. doi:10.1021/ja2062677Herrero-Latorre, C., Álvarez-Méndez, J., Barciela-García, J., García-Martín, S., & Peña-Crecente, R. M. (2015). Characterization of carbon nanotubes and analytical methods for their determination in environmental and biological samples: A review. Analytica Chimica Acta, 853, 77-94. doi:10.1016/j.aca.2014.10.008Stankovich, S., Dikin, D. A., Piner, R. D., Kohlhaas, K. A., Kleinhammes, A., Jia, Y., … Ruoff, R. S. (2007). Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide. Carbon, 45(7), 1558-1565. doi:10.1016/j.carbon.2007.02.034Bekyarova, E., Itkis, M. E., Ramesh, P., Berger, C., Sprinkle, M., de Heer, W. A., & Haddon, R. C. (2009). Chemical Modification of Epitaxial Graphene: Spontaneous Grafting of Aryl Groups. Journal of the American Chemical Society, 131(4), 1336-1337. doi:10.1021/ja8057327Barrejón, M., Pla, S., Berlanga, I., Gómez-Escalonilla, M. J., Martín-Gomis, L., Fierro, J. L. G., … Langa, F. (2015). Covalent decoration onto the outer walls of double walled carbon nanotubes with perylenediimides. Journal of Materials Chemistry C, 3(19), 4960-4969. doi:10.1039/c5tc00425jCriado, A., Vizuete, M., Gómez-Escalonilla, M. J., García-Rodriguez, S., Fierro, J. L. G., Cobas, A., … Langa, F. (2013). Efficient cycloaddition of arynes to carbon nanotubes under microwave irradiation. Carbon, 63, 140-148. doi:10.1016/j.carbon.2013.06.064Gómez-Escalonilla, M. J., Atienzar, P., Garcia Fierro, J. L., García, H., & Langa, F. (2008). Heck reaction on single-walled carbon nanotubes. Synthesis and photochemical properties of a wall functionalized SWNT-anthracene derivative. Journal of Materials Chemistry, 18(13), 1592. doi:10.1039/b717011dDel Canto, E., Flavin, K., Movia, D., Navio, C., Bittencourt, C., & Giordani, S. (2011). Critical Investigation of Defect Site Functionalization on Single-Walled Carbon Nanotubes. Chemistry of Materials, 23(1), 67-74. doi:10.1021/cm101978mGiordani, S., Colomer, J.-F., Cattaruzza, F., Alfonsi, J., Meneghetti, M., Prato, M., & Bonifazi, D. (2009). Multifunctional hybrid materials composed of [60]fullerene-based functionalized-single-walled carbon nanotubes. Carbon, 47(3), 578-588. doi:10.1016/j.carbon.2008.10.036Hahlin, M., Johansson, E. M. J., Plogmaker, S., Odelius, M., Hagberg, D. P., Sun, L., … Rensmo, H. (2010). Electronic and molecular structures of organic dye/TiO2 interfaces for solar cell applications: a core level photoelectron spectroscopy study. Physical Chemistry Chemical Physics, 12(7), 1507. doi:10.1039/b913548kKamat, S. V., Yadav, J. B., Puri, V., Puri, R. K., & Joo, O. S. (2011). Characterization of poly (3-methyl thiophene) thin films prepared by modified chemical bath deposition. Applied Surface Science, 258(1), 482-488. doi:10.1016/j.apsusc.2011.08.084Wagner, C. D., Davis, L. E., Zeller, M. V., Taylor, J. A., Raymond, R. H., & Gale, L. H. (1981). Empirical atomic sensitivity factors for quantitative analysis by electron spectroscopy for chemical analysis. Surface and Interface Analysis, 3(5), 211-225. doi:10.1002/sia.740030506Cuendet, P., Rao, K. K., Grätzel, M., & Hall, D. O. (1986). Light induced H2 evolution in a hydrogenase-TiO2 particle system by direct electron transfer or via Rhodium complexes. Biochimie, 68(1), 217-221. doi:10.1016/s0300-9084(86)81086-0Soldat, J., Marschall, R., & Wark, M. (2014). Improved overall water splitting with barium tantalate mixed oxide composites. Chem. Sci., 5(10), 3746-3752. doi:10.1039/c4sc01127