Factorial electrochemical design for tailoring of morphological and optical properties of Cu2O

[EN] The electrodeposition of cuprous oxide (Cu2O) onto FTO-coated glass substrate was studied by using a statistical approach in order to control the Cu2O morphology and optical properties. The factorial design considered four electrodeposition conditions at two representative levels as input variables (electrolyte temperature and pH, deposition potential and duration) and the deposition charge and morphology of obtained Cu2O as the output variables. The morphology analysis showed the highest influence on crystal shape was exhibited by electrolyte temperature and pH, reaching significance levels of 95 and 98%, respectively. Temperature as low as 35°C and pH 12.2 results in cubic morphology, while other parameters result in octahedron shape. The highest absorbance was exhibited by the Cu2O with cubic morphology.AP acknowledges financial support from Romanian National Authority for Scientific Research and Innovation, CNCS - UEFISCDI (project number PN-II-RU-TE-2014-4-0806].Cembrero-Coca, P.; Cembrero Cil, J.; Busquets Mataix, DJ.; Pérez Puig, MA.; Marí, B.; Pruna, AI. (2017). Factorial electrochemical design for tailoring of morphological and optical properties of Cu2O. Materials Science and Technology. 33(17):2102-2109. https://doi.org/10.1080/02670836.2017.1349595S210221093317Rakhshani, A. E. (1987). Measurement of dispersion in electrodeposited Cu2O. Journal of Applied Physics, 62(4), 1528-1529. doi:10.1063/1.339619Chen, L.-C. (2013). Review of preparation and optoelectronic characteristics of Cu2O-based solar cells with nanostructure. Materials Science in Semiconductor Processing, 16(5), 1172-1185. doi:10.1016/j.mssp.2012.12.028Hsu, Y.-K., Lin, H.-H., Wu, J.-R., Chen, M.-H., Chen, Y.-C., & Lin, Y.-G. (2014). Electrochemical growth and characterization of a p-Cu2O thin film on n-ZnO nanorods for solar cell application. RSC Advances, 4(15), 7655. doi:10.1039/c3ra47188hChou, S.-M., Hon, M.-H., Leu, I.-C., & Lee, Y.-H. (2008). Al-Doped ZnO∕Cu[sub 2]O Heterojunction Fabricated on (200) and (111)-Orientated Cu[sub 2]O Substrates. Journal of The Electrochemical Society, 155(11), H923. doi:10.1149/1.2980424Siegfried, M. J., & Choi, K.-S. (2004). Electrochemical Crystallization of Cuprous Oxide with Systematic Shape Evolution. Advanced Materials, 16(19), 1743-1746. doi:10.1002/adma.200400177Siegfried, M. J., & Choi, K.-S. (2005). Directing the Architecture of Cuprous Oxide Crystals during Electrochemical Growth. Angewandte Chemie International Edition, 44(21), 3218-3223. doi:10.1002/anie.200463018Yang, W.-Y., Kim, W.-G., & Rhee, S.-W. (2008). Radio frequency sputter deposition of single phase cuprous oxide using Cu2O as a target material and its resistive switching properties. Thin Solid Films, 517(2), 967-971. doi:10.1016/j.tsf.2008.08.184Reddy, A. S., Uthanna, S., & Reddy, P. S. (2007). Properties of dc magnetron sputtered Cu2O films prepared at different sputtering pressures. Applied Surface Science, 253(12), 5287-5292. doi:10.1016/j.apsusc.2006.11.051Laik, B., Poizot, P., & Tarascon, J.-M. (2002). The Electrochemical Quartz Crystal Microbalance as a Means for Studying the Reactivity of Cu[sub 2]O toward Lithium. Journal of The Electrochemical Society, 149(3), A251. doi:10.1149/1.1445430Fu, L. J., Gao, J., Zhang, T., Cao, Q., Yang, L. C., Wu, Y. P., … Wu, H. Q. (2007). Preparation of Cu2O particles with different morphologies and their application in lithium ion batteries. Journal of Power Sources, 174(2), 1197-1200. doi:10.1016/j.jpowsour.2007.06.030Zhou, Y., & Switzer, J. A. (1998). Electrochemical Deposition and Microstructure of Copper (I) Oxide Films. Scripta Materialia, 38(11), 1731-1738. doi:10.1016/s1359-6462(98)00091-8Budevski, E., Staikov, G., & Lorenz, W. J. (2000). Electrocrystallization. Electrochimica Acta, 45(15-16), 2559-2574. doi:10.1016/s0013-4686(00)00353-4Morales, J., Sánchez, L., Bijani, S., Martı́nez, L., Gabás, M., & Ramos-Barrado, J. R. (2005). Electrodeposition of Cu[sub 2]O: An Excellent Method for Obtaining Films of Controlled Morphology and Good Performance in Li-Ion Batteries. Electrochemical and Solid-State Letters, 8(3), A159. doi:10.1149/1.1854126Holzschuh, H., & Suhr, H. (1990). Deposition of copper oxide (Cu2O, CuO) thin films at high temperatures by plasma-enhanced CVD. Applied Physics A Solids and Surfaces, 51(6), 486-490. doi:10.1007/bf00324731Jeong, S., & Aydil, E. S. (2009). Heteroepitaxial growth of Cu2O thin film on ZnO by metal organic chemical vapor deposition. Journal of Crystal Growth, 311(17), 4188-4192. doi:10.1016/j.jcrysgro.2009.07.020Pruna, A., Pullini, D., & Busquets, D. (2015). Effect of AZO film as seeding substrate on the electrodeposition and properties of Al-doped ZnO nanorod arrays. Ceramics International, 41(10), 14492-14500. doi:10.1016/j.ceramint.2015.07.087Pruna, A., Pullini, D., Tamvakos, D., Tamvakos, A., & Busquets-Mataix, D. (2015). Effect of tin-doped indium oxide film on electrodeposition of ZnO nanostructures. Materials Science and Technology, 31(14), 1794-1799. doi:10.1179/1743284715y.0000000016Pruna, A., Reyes-Tolosa, M. D., Pullini, D., Hernandez-Fenollosa, M. A., & Busquets-Mataix, D. (2015). Seed-free electrodeposition of ZnO bi-pods on electrophoretically-reduced graphene oxide for optoelectronic applications. Ceramics International, 41(2), 2381-2388. doi:10.1016/j.ceramint.2014.10.052Cembrero, J., Pruna, A., Pullini, D., & Busquets-Mataix, D. (2014). Effect of combined chemical and electrochemical reduction of graphene oxide on morphology and structure of electrodeposited ZnO. Ceramics International, 40(7), 10351-10357. doi:10.1016/j.ceramint.2014.03.008Prună, A., Pullini, D., & Mataix, D. B. (2012). Influence of Deposition Potential on Structure of ZnO Nanowires Synthesized in Track-Etched Membranes. Journal of The Electrochemical Society, 159(4), E92-E98. doi:10.1149/2.003205jesJiang, X., Zhang, M., Shi, S., He, G., Song, X., & Sun, Z. (2014). Microstructure and optical properties of nanocrystalline Cu2O thin films prepared by electrodeposition. Nanoscale Research Letters, 9(1), 219. doi:10.1186/1556-276x-9-219Yu, X., Li, X., Zheng, G., Wei, Y., Zhang, A., & Yao, B. (2013). Preparation and properties of KCl-doped Cu2O thin film by electrodeposition. Applied Surface Science, 270, 340-345. doi:10.1016/j.apsusc.2013.01.026Bijani, S., Schrebler, R., Dalchiele, E. A., Gabás, M., Martínez, L., & Ramos-Barrado, J. R. (2011). Study of the Nucleation and Growth Mechanisms in the Electrodeposition of Micro- and Nanostructured Cu2O Thin Films. The Journal of Physical Chemistry C, 115(43), 21373-21382. doi:10.1021/jp208535

Improving the properties of Cu2O/ZnO heterojunction for photovoltaic application by graphene oxide

[EN] A p-Cu2O/n-ZnO heterojunction grown on fluorine-doped tin oxide (FTO) substrate is reported by a combined low-cost approach employing tape-casting of ZnO layer and subsequent electrochemical deposition of Cu2O layer. Graphene oxide (GO) nanosheets were employed as nanofiller for the ZnO matrix. Moreover, a ZnO buffer layer was inserted at the interface between the Cu2O and ZnO layers. The morphological, structural and photoelectrical characteristics of these heterojunction layers were investigated by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Raman spectroscopy and photoelectrical current-voltage measurements. The results confirmed that the morphology and structure of ZnO layer were affected by the incorporation of GO nanosheets while the presence of buffer layer influenced the growth of Cu2O layer. This work shows the addition of GO and the use of ZnO buffer layer represent a viable approach towards improving the photoelectrical properties of the Cu2O/ZnO heterojunction cell.Financial support from Escuela Politecnica Nacional, Ecuador (project number PIMI 15-09) and Secretaria de Education Superior, Ciencia, Tecnologia e Innovation (SENESCYT) and Romanian National Authority for Scientific Research and Innovation, Romania CNCS - UEFISCDI (project number PN-III-P1-1.1-TE-2016-1544) is gratefully acknowledged.Rosas-Laverde, NM.; Pruna, AI.; Busquets Mataix, DJ.; Marí, B.; Cembrero Cil, J.; Salas Vicente, F.; Orozco-Messana, J. (2018). Improving the properties of Cu2O/ZnO heterojunction for photovoltaic application by graphene oxide. Ceramics International. 44(18):23045-23051. https://doi.org/10.1016/j.ceramint.2018.09.107S2304523051441

Conditions for the growth of smooth La0.7Sr0.3MnO3 thin films by pulsed electron ablation

We report on the optimisation of the growth conditions of manganite La0.7Sr0.3MnO3 (LSMO) thin films prepared by Channel Spark Ablation (CSA). CSA belongs to pulsed electron deposition methods and its energetic and deposition parameters are quite similar to those of pulsed laser deposition. The method has been already proven to provide manganite films with good magnetic properties, but the films were generally relatively rough (a few nm coarseness). Here we show that increasing the oxygen deposition pressure with respect to previously used regimes, reduces the surface roughness down to unit cell size while maintaining a robust magnetism. We analyse in detail the effect of other deposition parameters, like accelerating voltage, discharging energy, and temperature and provide on this basis a set of optimal conditions for the growth of atomically flat films. The thicknesses for which atomically flat surface was achieved is as high as about 10-20 nm, corresponding to films with room temperature magnetism. We believe such magnetic layers represent appealing and suitable electrodes for various spintronic devices.Comment: original paper, thin film optimization, 25 pages, 9 figure

Synergistic effects in ZnO nanorod films by pulsed electrodeposition on graphene oxide towards enhanced photocatalytic degradation

[EN] In this work the synthesis, characterization and photocatalytic activity of novel graphene oxide-supported ZnO nanostructured film are reported. The ZnO film was deposited onto GO layer in a two-step procedure varying the deposition mode. The electrodeposited ZnO films were characterized by scanning electron microscopy (SEM), Xray diffraction (XRD), Fourier transform Infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The effect of the electrodeposition mode and GO presence on the properties of the ZnO nanostructured film was assessed. The applicability towards the adsorption, photodegradation of methylene blue (MB) for the obtained films was analyzed. The results indicated the electrodeposition pulses result in a strong interaction between ZnO and GO results, lower c-axis strain of the deposited ZnO and higher oxygen vacancies. Synergistic effect of oxygen vacancies and morphology towards degradation performance was indicated. Both adsorption and photocatalysis towards the degradation of MB on the modified ZnO films were observed, 52 % degradation efficiency being recorded in 90 min with a rate constant of 0.00171 min-1 under low UV irradiation, with respect to 5 % corresponding to ZnO film obtained in single step by direct mode and in absence of GO layer. A recycling experiment indicated excellent stability of the photocatalyst, the degradation efficiency reaching 98 % after 3 successive runs.This work is supported by Romanian Ministry of Research, Innovation and Digitization, CNCS-UEFISCDI, (project number PN-III-P4-PCE-2021-1278) , within PNCDI III.Pruna, AI.; Poliac, I.; Busquets Mataix, DJ.; Ruotolo, A. (2024). Synergistic effects in ZnO nanorod films by pulsed electrodeposition on graphene oxide towards enhanced photocatalytic degradation. Ceramics International. 50(3):4622-4631. https://doi.org/10.1016/j.ceramint.2023.11.2064622463150

Influence of SiC addition on mechanical behavior of thermal barriers with the aid of acoustic emission

[EN] The improvement of high temperature materials with lower heat transfer coefficients lead to the development of thermal barrier coatings (TBCs). One of the most widely used materials for thermal barrier coatings is Y2O3 stabilized ZrO2 (Y-TZP) because of its excellent shock resistance, low thermal conductivity, and relatively high coefficient of thermal expansion. The aim of this work is to study the TBCs mechanical behavior with the addition of SiC into the suspension of Y-TZP/Al2O3 by acoustic emission (AE). Additionally, a microstructural analysis and a finite elements model were carried out in order to compare results. The coatings were made by suspension plasma spray (SPS) on metal plates of 70 x 12 x 2 mm(3). An intermetallic was deposited as a bond coating, followed by a coating of Y-TZP/Al2O3 with and without 15 wt.% SiC, with thicknesses between 87 and 161 mu m. The AE becomes a fundamental tool in the study of the mechanical behavior of thermal barriers. The use of wavelet transforms streamlines the study and analysis of recorded sound spectra. The crack generation arises at very low stress levels.The authors wish to thank the financial contribution of the Ministry of Economy, Industry, and Competitiveness of the Government of Spain, (MINECO), and to the RTI 2018-099033-B-C32-RETOS. A. Borrel acknowledges her contract (RyC-2016-20915).Busquets Mataix, DJ.; Bloem, C.; Borrell Tomás, MA.; Salvador Moya, MD. (2021). Influence of SiC addition on mechanical behavior of thermal barriers with the aid of acoustic emission. Journal of Composites Science. 5(1):1-19. https://doi.org/10.3390/jcs5010016S1195