ELECTRODEPOSIT OF Ni-Fe ALLOY AS CATHODE IN ALKALINE WATER ELECTROLYSIS

• Main Author: Mu'minah, Qonita
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/41441
• Institution: Institut Teknologi Bandung

Ni-Fe alloys are known to have potential as electrocatalytic material in the Hydrogen Evolution Reaction (HER). Electrocatafyst material must have good intrinsic properties and swface morphology that support the reduction of water molecules. The intrinsic properties of a metal can be improved by combining it. The role of Ni-Fe alloy can reduce the overpotential value for the electrolysis reaction of vv•a:er in an alkaline condition. In this study•, l'v'i-Fe a/loy•'At•ere S}'l1thesized using the modified Watts bath type electrodeposition method with the addition of boric acid, saccharin and trisodium citrate. Reaction optimization was earned out at current densities of 5, 15. and 25 rnA cm2 where optimum conditions were obtained at a current dens•ity of25 rnA cm 2 at 55 °C with a pH of2.20±0.02for 160 minutes. One parameter that a_(lects deposits is the pH of the solution at the electrode inteiface. Boric acid acts as a bujf"er solution that serves to maintain the pH ofthe solution at the electrode interface so that there was no sign ficant increase. At pH 1.99 the fomwtion of Fe(OH)J inhibits the deposition of Fe and Ni metals. Saccharin and trisodium citrate are used as internal stress reducer and complexing agents in the electrodeposirion process wirh varying concentrations of 1 and 5 g L for sacchann. In addltlon, vanatwns m the concentratwn of tron (III) chionde hexahydrate were carried out at 2.1, 2.8, and 3.6 g L. The higher concentration of ferric ions in solution increases the internal stresses of the deposition process. The crystalline phase of the electrodeposit produced was confirmed using the Powder X-Ray Di:ffractions (PXRD) method with a d[ffraction peak at 2fJ, i.e -1-1.03° and 51.28° corresponding to the ,"AliJFe phase there was also a diffraction peak at 28, i.e -13.8]0, 50.9-1°, and 75.3-1° which corresponds to the NiFe phase. However, in the etystalline phase NiFe formed a blackened suiface and peeling due to internal stress. The size ofNi- Fe metal alloy crystallites was calculated using the Scherrer equation where variations in saccharin and ferric ions concentrations a_ffect the 5;ize ofthe crystallites sized. Elemental component analysis on the deposit swface was carried out using the t•nergy Dispersive X-Ray Spectroscopy (EDX EDS) method which shows that there are oxygen and carbon impurities present. Both are formed due to the nature of saccharin which is eas;/y polarized and when the formation of FeOH •. Fe0H 2 + . and NiOH species are adsorbed on the surface of the substrate, there are some species that are not reduced lO metals and hydroxide ions. ()ve;potential n1easuren1en:s for the rrater reduction reaction rvere carried out electrochemically by the polarization method using the Tafel plot . ... Ill Overpotential values of-250, -76-1, and -889 mVwere obtained respectively when the electrodeposit NiJFe, Ni, and stainless steel were used as cathode in the electrolysis reaction ofwater in I M KOH at room temperature. Next, Hofmann voltameter was used to observe the catalytic effectivity of NiJFe on HER by measuring the volume of hydrogen gas produced. The dependent variables J-.n •.,• n ,/ ""'""' fln .- A /,.M<n A f /.,.,-}""" r• M A rl""" ,-} ,/.,, ;HAnmAn H+ "'" '_;J-.Jn VU ._lt-1 VC:.U YVt;....l C. tllC.. VVIU/IIC. V.J VC,t;;.H b,U.J j-11 UU . HL-t.:-U, lilt;. lltU.C..jJC,IIU!VIlL YU//.UUlf;:;. J that were mod fied. including the type of electrolyte solution, the concentration of the alkaline solution that varied, and the type of cathode that was compared between NiJFe alloys that had been .\ynthesi::ed with other cathodes which were easilyfound in everyday We. The production rate a_( h-ydrogen alloy NiJFe o_(0.009 cc minutes was obtained at a potential application o.f 2.5 V in a 0.10 M KOH solution. The simplicity of the Ho_fmann voltameter tool in measuring catalytic activity can be used as a learning tools for electrocatalyst material in chemistry subjects in senior high school level. Some mod({tcations to some equipment that might be simpler such as scale test tubes and balteries as a source of DC power supply.