Susanto, Susanto (2024) Sintesis Aerogel Karbon Terdoping N dan Aplikasinya sebagai Elektrokatalis Reaksi Reduksi Oksigen pada Katoda dalam Baterai Air Laut. Doctoral thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Proses yang memegang peranan penting dalam baterai air laut dengan system baterai logam–udara adalah reaksi reduksi oksigen selama discharge process pada katoda. Namun reaksi reduksi oksigen tersebut berlangsung dengan lambat. Oleh karena itu diperlukan pengembangan desain katoda dengan elektrokatalis reduksi oksigen dengan performa tinggi. Pada penelitian ini dikembangkan penelitian elektrokatalis berbasis karbon terdoping N dengan penambahan oksida logam non mulia. Aerogel karbon dapat disintesis dari polimer alam berbasis selulosa dari limbah pertanian berupa tandan kosong kelapa sawit mengandung selulosa 49% dan serabut kelapa mengandung selulosa 39%. Tipe gugus fungsi nitrogen pada karbon terdoping N terdiri dari pyrolic N, pyridinic N, dan graphitic N yang pembentukannya dipengaruhi oleh suhu pirolisis. Dari ketiga jenis N–doping tersebut, Pyridinic N paling efisien untuk aktivitas reaksi reduksi oksigen yang aktivitasnya dipengaruhi oleh konsentrasi N–doping. Penambahan oksida logam non mulia berbasis Fe dan Mn pada karbon terdoping N dapat meningkatkan peforma elektokatalis reaksi reduksi oksigen jika dibandingkan tanpa penambahan oksida logam. Oleh karena itu perlu dieksplore material karbon dengan yang memiliki banyak pori–pori dengan kandungan N–doping jenis Pyridinic N dan juga dilakukan penambahan oksida logam berbasis Fe dan Mn untuk meningkatkan peforma reaksi reduksi oksigen pada katoda baterai pada sistem baterai air laut dengan sistem baterai magnesium–udara dengan elektrolit NaCl 3,5%. Bab 2 diuraikan mengenai pengaruh suhu pirolisis terhadap jenis N doping pada aerogel karbon yang disintesis dari pirolisis aerogel selulosa dengan sistem crosslinking urea–ammonia berbasis serat sabut kelapa dan tandan kosong kelapa sawit. N–doping tipe pyrolic N didominasi pada pirolisis suhu 600 ℃, pyridinic N didominasi pada pirolisis suhu 700 ℃, dan graphitic N didominasi pada pirolisis suhu 800 ℃. Pengujian secara elektrokimia menunjukkan bahwa pyridinic N yang berfungsi memfasilitasi reaksi reduksi oksigen dan memiliki peforma lebih baik sebagai elektrokatalis reaksi reduksi oksigen dibandingkan pyrolic N dan graphitic N. Reaksi reduksi oksigen menggunakan pyridinic N mengikuti jalur 4 elektron yang secara kuantitatif berdampak pada proses kestabilan elektrokimia. Pada aplikasi baterai air laut menggunakan anoda Mg alloy dengan elektrolit NaCl 3,5% yang menggunakan katoda aerogel karbon berbasis tandan kosong kelapa sawit yang dipirolisis pada suhu 700°C memiliki kapasitas discharge 492,64 m Ah g–1 dan energi discharge 529,49 m Wh g–1. Bab 3 diuraikan mengenai pengaruh konsentrasi amonia terhadap jenis N doping pada aerogel karbon dari hasil pirolisis aerogel selulosa berbasis serat sabut kelapa dan tandan kosong kelapa sawit dengan system cross–linking NaOH–Ammonia–Urea. Pyrolic N didominasi pada rasio mol NaOH : NH4OH 1:1, Pyridinic N didominasi pada rasio 1:2, dan graphitic N didominasi pada rasio 1:3 dan 1:4. Karakteristik dan peforma elektrokimia terbaik dicapai oleh aerogel karbon berbasis sabut kelapa dan tandan kosong kelapa sawit pada rasio mol NaOH : NH4OH 1:2. Peforma elektrokimia reaksi reduksi oksigen terbaik diperoleh juga pada aerogel karbon berbasis tandan kosong kelapa sawit yang disintesis pada pada rasio mol NaOH : NH4OH 1:2 sebagai katoda udara dalam baterai air laut sistem magnesium–udara dengan dengan voltase mencapai 1,26 V dalam waktu discharge selama 30,72 jam dan memiliki energy density sebesar 2398,89 mW h g–1 dan specific capacity 1978,41 mA h g–1. Bab 4 diuraikan mengenai sintesis aerogel karbon terdoping N dengan penambahan oksida logam Fe@MnFeO2 dari hasil pirolisis 700 ℃ pada aerogel selulosa berbasis tandan kosong kelapa sawit dengan system cross–linking NaOH–NH4OH–urea melalui penambahan garam logam FeCl3 dan MnCl2 secara impregnasi pada rasio mol Fe:Mn. Penambahan oksida logam Fe@MnFeO2 pada aerogel karbon terdoping Pyridinic N meningkatkan peforma elektrokatalis reaksi reduksi oksigen. Peforma elektrokimia terbaik sebagai elektrokatalis reaksi reduksi oksigen diperoleh oleh aerogel karbon terdoping Pyridinic N dengan penambahan oksida logam Fe@MnFeO2 yang disintesis rasio mol Fe:Mn 1,5:1,5 sebagai katoda udara dalam baterai air laut sistem magnesium–udara dengan dengan voltase discharge stabil pada 1,33 V dalam waktu discharge selama 70 jam memiliki densitas energi discharge sebesar 4125,62 mW h g1 dan kapasitas spesifik discharge 3124,78 mA h g–1. Bab 5 diuraikan mengenai sintesis aerogel karbon terdoping N dengan penambahan oksida logam Fe3O4 dan MnO2 dari hasil pirolisis 700 ℃ pada aerogel selulosa berbasis tandan kosong kelapa sawit dengan system cross–linking NaOH–NH4OH–urea melalui penambahan garam logam FeCl3 secara impregnasi dan penambahan KMnO4 secara hidrotermal telah berhasil disintesis. Penambahan oksida logam Fe3O4 dan MnO2 pada aerogel karbon terdoping Pyridinic N yang memiliki peforma elektrokatalis bifungsional reaksi reduksi oksigen dan reaksi evolusi oksigen. Peforma elektrokimia terbaik sebagai elektrokatalis bifungsional reaksi reduksi oksigen dan reaksi evolusi oksigen diperoleh oleh aerogel karbon terdoping Pyridinic N dengan penambahan Fe3O4 sebagai katoda udara dalam baterai air laut sistem magnesium–udara dengan dengan voltase discharge stabil pada 1,4 V dalam waktu discharge selama 93,77 jam memiliki densitas energi discharge sebesar 5993,62 mW h g–1 dan kapasitas spesifik discharge 4216,93 mA h g–1 sedangkan pada proses charge dengan voltase charge stabil pada 1,83 V.
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The oxygen reduction reaction in the cathode during the discharge process of batteries is an important process in the seawater batteries with metal–air battery systems. However, the process of oxygen reduction reaction occurs at a slow rate. Therefore, it is imperative for developing a cathode structure combining an oxygen reduction electrocatalyst with high performance. This study developed an N–doped carbon–based electrocatalyst by the addition of non–precious metal oxides. Carbon aerogel can be synthesized from cellulose–based natural polymers derived from agricultural waste, namely palm empty fruit bunches with a cellulose content of 49% and coir fibers with a cellulose content of 39%. This work used coir fibers and palm empty fruit bunches that had abundant supplies of cellulose to synthesize carbon aerogel. The type of nitrogen functional group on N–doped carbon consists of pyrolic N, pyridinic N, and graphitic N. These formations are influenced by the pyrolysis temperature. Among the three forms of N–doping, Pyridinic N is the most effective for oxygen reduction processes. The concentration of N–doping has an impact on the activity of these reactions. The addition of non–precious metal oxides based on Fe and Mn to the doped carbon N can improve the electrocatalyst performance of oxygen reduction reactions when compared without the addition of metal oxides. Therefore, it is imperative to investigate carbon materials that possess multiple pores along with a significant Pyridinic N–doping content. Furthermore, the addition of metal oxides based on Fe and Mn is important for enhancing the performance of the oxygen reduction reaction at the cathode of seawater battery systems, specifically those utilizing magnesium–air battery systems with a 3.5% NaCl electrolyte. Chapter 2 describes the effect of pyrolysis temperature on type N doping in carbon aerogel. The carbon aerogel was generated from cellulose aerogel based on coir fibers and palm empty fruit bunches using a urea–ammonia crosslinking method by pyrolysis process. N–doping type pyrolic N is dominated by pyrolysis temperature of 600 ℃, pyridinic N is dominated by pyrolysis temperatures of 700 ℃, and graphitic N is dominated by pyrolysis temperatures of 800 ℃. Electrochemical testing shows that pyridinic N facilitates oxygen reduction reactions and has better performance as an electrocatalyst for oxygen reduction reactions than pyrolic N and graphitic N. Oxygen reduction reaction uses pyridinic N following a 4–electron pathway that quantitatively impacts electrochemical stability processes. In seawater battery applications using Mg alloy anode with 3.5% NaCl electrolyte and cathode of carbon aerogel based on palm empty fruit bunches by pyrolysis at 700 ℃. has a discharge capacity of 492.64 mA h g–1 and discharge energy of 529.49 mW h g–1. Chapter 3 describes the effect of ammonia concentration on type N doping on carbon aerogels from the pyrolysis of cellulose aerogels based on coir fibers and palm empty fruit bunches with NaOH–Ammonia–Urea cross–linking system. Pyrolic N is dominated at the mole ratio of NaOH : NH4OH 1:1, Pyridinic N is dominated at the ratio of 1:2, and graphitic N is dominated at the ratio of 1:3 and 1: 4. The best electrochemical characteristics and performance are achieved by carbon aerogels based on coir fibers and palm empty fruit bunches at a mole ratio of NaOH : NH4OH 1:2. The best electrochemical performance was also obtained on carbon aerogel based on palm empty fruit bunches with which was synthesized at a mole ratio of NaOH : NH4OH 1:2 as an air cathode in a magnesium–air system seawater battery with a voltage of 1.26 V in a discharge time of 30.72 hours and an energy density of 2398.89 mW h g–1 and a specific capacity of 1978.41 mA h g–1. Chapter 4 describes the synthesis of N–doped carbon aerogel with the addition of Fe@MnFeO2 metal oxide by the pyrolysis of 700 ℃ from cellulose aerogel based on palm empty fruit bunches with NaOH–NH4OH–urea cross–linking system through the addition of FeCl3 and MnCl2 metal salts by impregnation at the mole ratio of Fe:Mn. The addition of Fe@MnFeO2 metal oxide to pyridinic N–doped carbon aerogel enhances the electrocatalyst performance of the oxygen reduction reaction. The best electrochemical performance as an oxygen reduction reaction electrocatalyst was obtained by Pyridinic N doped carbon aerogel with the addition of Fe@MnFeO2 metal oxide synthesized Fe:Mn moleratio of Fe:Mn 1.5:1.5 as an air cathode in magnesium–air system seawater battery with a discharge voltage stable at 1.33 V within 70 hours of discharge, a discharge energy density of 4125.62 mW h g1 and a discharge specific capacity of 3124.78 mA h g–1. Chapter 5 describes the synthesis of N–doped carbon aerogel with the addition of metal oxides Fe3O4 and MnO2 from the pyrolysis of 700 ℃ on cellulose aerogel based on palm empty fruit bunches with NaOH–NH4OH–urea cross–linking system through the addition of FeCl3 solution by impregnation method and the addition of KMnO4 solution by hydrothermal method has been successfully synthesized. The addition of metal oxides Fe3O4 and MnO2 into Pyridinic N–doped carbon aerogel provides a bifunctional electrocatalyst capable of facilitating both the oxygen reduction process and the oxygen evolution reaction. The best electrochemical performance as a bifunctional electrocatalyst of the oxygen reduction reaction and the evolutionary reaction of Oxygen is obtained by the carbon aerogel coated with Pyridinic N with the addition of Fe3O4 as an air cathode in the seawater batteries of the magnesium–air system with a voltage discharge stable at 1.4 V during discharges time for 93.77 hours has a discharge energy density of 5993.62 mW h g-1 and a discharge specific capacity of 4216.93 mA h g–1 while on the charge process with a voltage charge stable on 1.83 V.
| Item Type: | Thesis (Doctoral) |
|---|---|
| Uncontrolled Keywords: | Cellulose Aerogel, Seawater battery, N–doped carbon, Metal oxides based on Fe and Mn, Pyridinic N, Oxygen reduction reaction,Aerogel selulosa, Baterai air laut, Karbon terdoping N, Oksida logam berbasis Fe dan Mn, Pyridinic N, Reaksi reduksi oksigen |
| Subjects: | T Technology > TP Chemical technology T Technology > TP Chemical technology > TP255 Electrochemistry, Industrial. |
| Divisions: | Faculty of Industrial Technology > Industrial Engineering > 26001-(S3) PhD Thesis |
| Depositing User: | Susanto Susanto |
| Date Deposited: | 14 Aug 2024 03:12 |
| Last Modified: | 14 Aug 2024 03:12 |
| URI: | http://repository.its.ac.id/id/eprint/115358 |
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