https://ptsldigital.ukm.my/jspui/handle/123456789/388915 2026-04-25T09:14:02Z https://ptsldigital.ukm.my/jspui/handle/123456789/781700 Title: Sintesis membran komposit sulfonasi poli (eter eter keton)/grafitik karbon nitrida terfosforilasi untuk aplikasi sel fuel borohidrida langsung Authors: Nur Ain Masleeza Harun (P112540) Abstract: Sel Fuel Borohidrida Langsung (DBFC) merupakan teknologi sel fuel cecair yang amat menggalakkan. Membran elektrolit polimer memainkan peranan penting dalam DBFC. Secara tradisinya, membran asid perfluorosulfonik komersial, Nafion, telah menjadi pilihan utama. Namun begitu, penggunaannya yang meluas dihalang oleh kos yang tinggi dan isu kebolehtelapan borohidrida yang tinggi. Oleh itu, penyelidikan ini meneroka kaedah yang mampan untuk mensintesis membran pertukaran kation (CEM), sambil menangani kebimbangan mengenai isu kestabilan mekanikal, kebolehtelapan borohidrida, dan kekonduksian ionik. Dalam kajian ini, sulfonasi poli (eter eter keton) (SPEEK) disintesis melalui kaedah sulfonasi langsung, manakala grafitik karbon nitrida (GCN) disintesis melalui kaedah in-situ. Pengaruh GCN terhadap membran SPEEK dikaji melalui fabrikasi membran komposit SPEEK/GCN menggunakan teknik tuangan larutan. Semua membran komposit telah dicirikan menggunakan inframerah jelmaan fourier (FTIR), spektroskopi fotoelektron sinar-X (XPS), pembelauan sinar-X (XRD), mikroskopi imbasan elektron medan emisi (FESEM), mesin ujian universal (UTM), dan analisis termogravimetri (TGA). Sifat elektrokimia membran komposit dinilai berdasarkan kekonduksian ionik dan kebolehtelapan borohidrida. Imej FESEM menunjukkan penyebaran seragam pengisi GCN dalam matriks polimer SPEEK. Pemerhatian ini disokong oleh analisis XRD, yang menunjukkan pengedaran sekata bagi interkalasi GCN antara molekul SPEEK. Membran komposit SPEEK/GCN-1.0 mengatasi membran SPEEK tulen dalam kekuatan tegangan (26.85 MPa), kekonduksian ionik (1.28 mS cm-1), dan kebolehtelapan borohidrida (1.53 × 10-6 cm2 s-1). Namun begitu, kekonduksian ionik bagi SPEEK/GCN-1.0 masih lagi rendah berbanding Nafion, telah mendorong kepada pembangunan GCN terfosforilasi (PGCN),yang disediakan melalui rawatan dengan menggunakan asid fosforik pekat, dan diintegrasikan ke dalam matriks SPEEK melalui teknik tuangan larutan. Membran komposit SPEEK/PGCN yang optimum (1.5 bt.%) menunjukkan kekonduksian ionik tertinggi (1.32 mS cm-1) jika dibandingkan dengan SPEEK tulen (1.05 mS cm-1) dan membran Nafion komersial (1.30 mS cm-1). Peningkatan ini disebabkan oleh kehadiran kumpulan asid fosforik, yang mewujudkan lebih banyak laluan untuk pengangkutan ion. Akhirnya, membran yang dioptimum diaplikasikan pada sel tunggal DBFC pasif, di mana membran komposit SPEEK/PGCN-1.5 menunjukkan ketumpatan kuasa yang lebih tinggi (19.95 mW cm-2) berbanding membran SPEEK/GCN-1.0 (15.93 mW cm-2) dan membran Nafion (16.26 mW cm-2). Kajian ini menekankan bahawa penggabungan GCN dan PGCN mampu meningkatkan kestabilan mekanikal, kekonduksian ionik, dan mengurangkan kebolehtelapan borohidrida. Description: Partial 2025-08-07T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/781693 Title: Formulasi pemangkin kuprum-stanum untuk penurunan elektrokimia CO2 dalam sel elektrosintesis mikrob Authors: Irwan Ibrahim (P112458) Abstract: Proses penurunan CO2 menggunakan pendekatan bioelektrokimia merupakan satu bidang yang masih baru dalam dunia kajian. Sistem mikrob elektrosintesis atau microbial electrosynthesis system (MES) merupakan sistem bioelektrokimia yang menggunakan mikrob elektrogenik, iaitu mikrob yang menggunakan elektrik sebagai tenaga untuk proses penurunan karbon dioksida (CO2) dalam menghasilkan sebatian kimia melalui tindakbalas penurunan CO2. Kajian ini, menggunapakai MES untuk menghasilkan asid formik menggunakan mikrob elektrogenik. Proses ini dipercepatkan dengan menggunakan pemangkin biokatod yang diubahsuai melalui proses penyaduran elektrokimia untuk menambah lapisan stanum-kuprum oksida diatas permukaan kain karbon. Kuprum dan stanum merupakan logam yang di kenal pasti mampu meningkatkan kadar tindak balas penurunan CO2 kepada sebatian yang bersifat hidrokarbon, iaitu formik dalam kajian ini. Melalui kajian yang di jalankan yang terdiri daripda CuSn-EDTA, CuSnSb-EDTA, CuSn-NaCit, dan CuSnSb-NaCit, sebatian CuSnSb-EDTA telah dikenal pasti menggunakan FESEM-EDX menunjukkan struktur kristal berbentuk bunga yang terbentuk melalui tindak balas nukleasi dengan taburan aloi gangsa yang agak seimbang. Dengan mengaplikasi katod komposit tersebut, sistem MES telah menunjukkan penghasilan ketumpatan arus dan purata voltan yang stabil dan tertinggi pada -19.14 A/cm2 dan -0.49 V dan kadar penghasilan formik sehingga 0.137 M/d. Analisa kitaran voltametri sel penuh pula menunjukkan CuSn biokatod mencatatkan puncak penurunan yang terendah pada voltan -1.0 V, iaitu bersamaan dengan voltan gunaan semasa operasi MES. Description: Partial 2024-09-30T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/781692 Title: Characterization of platinum-coated titanium bipolar plate for polymer electrolyte membrane water electrolyzer Authors: Al-Shami, Ibrahim Ahmed Yahya (P110960) Abstract: Polymer Electrolyte Membrane Water Electrolyzer (PEMWE) are electrochemical energy conversion devices that split water into its constituent elements of hydrogen and oxygen. Bipolar plate (BPP) is one of the key components in PEMWE systems due to their essential rules in the operation of PEMWE for supporting the electrode and membrane structure mechanically and conducting electrons between each cell. To date, titanium (Ti) is the most promising candidate for metal-based BPP due to its strength, resistance to heat, water and salt, also the fact that it is lightweight. However, pure Ti has insufficient long-term stability and performance due to the continuous formation of the Ti-oxide layer during longer operations leading to an increase in Interfacial Contact Resistance (ICR) and deteriorating overall performance. Therefore, the use of an additional coating layer on the Ti surface is an effective method to prevent the formation of an oxide layer as well as increase the corrosion resistance of the base material. This study aims to develop a uniform and reliable protective coating for Ti BPP using platinum (Pt) as the coating layer with the electrodeposition technique. The objectives of this study is to examine various parameters that influence the quality of Pt coating including pre-treatment strategies, plating current density and heat treatment. The effect of applying acid pickling/Ni-strike pre-treatment combined in the same working bath was investigated on the morphological structure and electrochemical properties of the Pt coating. The intermediate Nickel (Ni) layer effectively protected the Ti surface from re-oxidation, evidenced by a significant 91% reduction in ICR for PNC sample compared to pure Ti. Additionally, the coating morphology of the pre-treated samples showed a more uniform coating layer with fewer defects/holes compared to the sample without pre-treatment. As the next step, the effects of varying plating current densities and heat treatments were further studied in this research. Current densities of 10, 20, 30, and 40 mA/cm2 were tested, and it was found that the Pt layer produced at a current density of 30 mA/cm2 had a uniform coating layer with no visible defects/holes and consistent Pt crystal size distribution and a thickness of 2 μm. Furthermore, the sample coated at 30 mA/cm2 had the lowest polarization resistance at 24.1 KΩ among other samples. In addition, it was determined that the heat treatment tested at 400, 600 and 800 ºC had no clear advantage on the coating morphology and electrochemical properties over untreated samples. Moreover, a long-term durability test of the Ptcoated layer using the optimized coating procedures in a PEMWE simulation environment was investigated. An extended chronoamperometric (CA) test for 80 hours was performed and the electrochemical properties and morphology of the sample were tested and compared before and after the durability test. The sample coated using the optimized coating procedures showed a steady current density output at 5 mA, indicating that the cell performance is constant with no degradation at a voltage of 2 V. Additionally, the ICR and polarization resistance of the sample were measured before and after the durability test and no significant increase was observed. Therefore, this work has demonstrated that Pt-coated Ti fabricated using an electrodeposition technique at 30 mA/cm2 and having a thickness of 2 μm, coupled with acid pickling/Nistrike pre-treatment is a promising method to produce a uniform, reliable protective Pt coating on Ti surface for PEMWE BPP application. Description: Full-text 2024-01-17T00:00:00Z https://ptsldigital.ukm.my/jspui/handle/123456789/781691 Title: Fabrication of catalyst coated membrane electrode assembly for water electrolyzer using decal method Authors: Bazarah, Ammar Gamal Abdulhameed (P109806) Abstract: Proton Exchange Membrane Electrolyzer (PEMEL) is a device that uses electricity to split water into hydrogen and oxygen. It is a promising technology to produce hydrogen gas, which is considered a clean and renewable energy source. The catalyst coated membrane (CCM) method is simpler and more efficient than the indirect coating method involving a transfer after coating on the substrate. However, the direct deposition of catalyst onto the membrane could be complicated by the transfer rate of the membrane during the coating process. This transfer rate poses a challenge in achieving consistent and high-quality catalyst coatings on the membrane surface. Therefore, controlling and mitigating the transfer rate of the catalysts to the membrane is of crucial importance in the CCM method for the fabrication of high-quality membrane electrode assemblies (MEAs) used in proton exchange membrane electrolyzers. This study aims to manufacture and optimize a catalyst-coated membrane electrode assembly (CCM-MEA) for a laboratory-scale proton exchange membrane water electrolyzer (PEMWE) using the decal method to achieve the highest transfer rate of the catalyst and to study other parameters that may influence the MEAs efficiency and durability. In this study also investigates and tests the long-term performance and durability of the MEAs. The CCM-MEA was manufactured using Nafion 117 and Nafion 212 membranes of different sizes (5 cm2, 25 cm2 and 36 cm2) with IrO2 coating on the anode side and Pt/c on the cathode side. The CCM was prepared using the decal method and different transfer substrates were tried such as PTFE, Kepton and Teflon cloth. To facilitate the transfer, a thin ionomer layer was added on top of the catalysts and the sample was sandwiched between a folded piece of aluminium foil before the hot press stage. For the hot press condition, the temperature was 130 °C, the pressure was 700 psi, and the time was 5 minutes. After the hot press, cold peeling of the sample by leaving it to cool down for 3 minutes. The performance of the CCM-MEA was evaluated in terms of current density under different operating temperatures (room temperature, 30 °C, and 60 °C). The results showed that the 36 cm2 using Nafion 117 at 2.0 voltage had the best performance among all the sizes of membrane used. Additionally, it was found that the Teflon cloth had the best catalysts transfer rate of over 95% among other transfer substrates. The result of this study provides insight on the optimal design, the long-term performance, and durability of the MEAs for PEMWE. Description: Partial 2024-04-24T00:00:00Z