Available free online at www.medjchem.com Mediterranean Journal of Chemistry 2020, 9(6), 456-467 *Corresponding author: Yassine Salhi Received September 15, 2019 Email address: y.salhi33@gmail.com Accepted October 28, 2019 DOI: http://dx.doi.org/10.13171/mjc9601071073ys Published January 7, 2020 Electrodeposition of Cu-Zn-Sn coating in citrate medium Yassine Salhi 1,* , Sghir Cherrouf 1 , Jihane Tellal 1 and Mohammed Cherkaoui 1,2 1 Laboratory of Materials, Electrochemistry and Environment, Faculty of Science, Ibn Tofail University, Po Box 133-14050, Kenitra, Morocco 2 National Higher School of Chemistry, Ibn Tofail University, Po Box 133-14050, Kenitra, Morocco Abstract: The electrodeposition of Cu-Zn-Sn (CZT) coating at ambient temperature was investigated. The bath consists of metal salts SnSO4, ZnSO4,7H2O and CuSO4,5H2O and sodium citrate (NaC6H5Na3O7,2H2O) as a complexing agent. For precipitation, the pH is maintained at 5. The reducing of copper, tin and zinc through Cu2HCit 3− , Sncit 2− and ZnHcit − complexes respectively are confirmed by the presence of three cathodic peaks on the voltammograms realized on steel and ITO glass substrate. X-ray diffraction patterns revealed peaks corresponding to the phases: Cu-Zn cubic, Cu-Sn hexagonal and β-Sn tetragonal. The deposition rate is 35 μm/h. SEM observation and EDAX analysis showed that the coating consists of a uniform CZT layer of which composition is 55% copper, 20% zinc and 25% tin at -1.5V. A preliminary study showed a remarkable improvement in the corrosion resistance of CZT coated steel in comparison with bare steel. Keywords: Cu-Zn-Sn (CZT) coating, citrate, electrodeposition, voltammetry, ITO, characterization, corrosion resistance. 1. Introduction Cu-Zn-Sn (CZT) alloys coatings exhibit exciting characteristics: good corrosion resistance 1-5 , excellent solderability 6-9 , good ductility 10-12 , no toxicity 13,14 and beautiful appearance and smooth morphology 15,16 . Thus, they are applied as a finish coat in many domains such as marine industry 1 , the automobile industry 3,8 , microelectronics 17,18 , aeronautics 18 , food industry 19 . Also, CZT deposits were used to prevent dezincification and improve the electrical properties of the Sn-Zn binary system by adding copper 20 . Furthermore, tin, zinc and copper are the main parts that constitute the layers used in photovoltaic cells when combined with sulfur or selenium to form quaternary deposits (Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe )) 21-23 . Kesterite Cu2ZnSnS4 (CZTS) thin films are attracting much interest as an alternative system to Cu(In, Ga)Se2 (CIGS) and CdTe thin films because In, Ga and Te are rare and expensive elements and the other reason is the toxicity of cadmium 24-29 . We also note that CZTS thin films offer excellent properties such as good mechanical properties and good absorption coefficient 28 . Besides, CZTS film contains Zn and Sn that are naturally abundant, very cheap materials to replace In and Ga. Beside, CZTS thin film has the same tetragonal structure as that of CIGS 29,30 . The major problem of co-deposition of metals is to bring their reduction potential closer. The addition of complexants in baths is a simple and effective solution. Thus, various complexing agents have been used in the case of the alloy CZT: tartrate 2 , gluconate 10 , citrate 4,13,20 and trisodium nitrilotriacetic 31 . In a previous Sn-Zn alloy electrodeposition study, we have chosen citrate to co-deposit tin and zinc because of the stability of the bath at a near-neutral pH in order to make industrial application easy 32 . We have opted for the same complexant in the case of the CZT ternary alloy coating electrodeposition. We have used the thermodynamic model of Kazimierczak H. et al. to determine the optimal pH range to obtain a stable electrolyte 4 . The CZT coating was carried out on copper and common steel substrates for the electrochemical study then on ITO glass in order to fabricate CZT precursor layers for a possible application in photovoltaic cells. On the other hand, morphology, composition, crystallographic study and corrosion resistance of CZT deposits were characterized by SEM, EDX, DRX and electrochemical impedance.