Sains Malaysiana 49(7)(2020): 1745-1754

http://dx.doi.org/10.17576/jsm-2020-4907-24

Enhancement of Characteristics of Nitrogen-Doped Graphene Composite Materials Prepared by Ball Milling of Graphite with Melamine: Effect of Milling Speed and Material Ratios

(Penambahbaikan Ciri-Ciri Bahan Komposit Nitrogen Terdop Grafin Menggunakan Kaedah Penggilingan Bola Campuran Grafit dan Melamin: Kesan Kelajuan Penggilingan dan Nisbah Bahan)

NURUL AIN HUZAIFAH¹, NORDIN SABLI^1,2*, KOK KUAN YING³, NUR UBAIDAH SAIDIN³ & HIKMAT S. HILAL⁴

¹Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia

²Institute of Advance Technology (ITMA), Universiti Putra Malaysia (UPM), 43400 UPM Serdang, Selangor Darul Ehsan, Malaysia

³Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor Darul Ehsan, Malaysia

⁴Semiconductor & Solar Energy Research Laboratory, Department of Chemistry, An-Najah National University, Nablus, West Bank, PO Box 7, Palestine

Diserahkan: 29 Oktober 2019/Diterima: 20 Mac 2020

                                                                  ABSTRACT

Nitrogen-doped graphene has been prepared using the ball milling method that is known to be eco-friendly, scalable and economic. The parameters studied in the synthesis were the mass ratio of starting materials (graphite and melamine) and speed of the ball milling. To determine its structure and properties, the nitrogen-doped graphene was characterized using Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray (FESEM-EDX), RAMAN Spectroscopy and X-Ray Diffraction (XRD). Based on FESEM-EDX analysis, the doped composite exhibited nitrogen content of ~3.5%. The nitrogen-doped graphene was examined as a replacement for platinum catalysts in fuel cells. Different composite catalysts were evaluated using a Rotating Disk Electrode (RDE) to test the Oxidation Reduction Reaction (ORR) performance. Based on ORR performance comparison, the composite with highest performance was then used to fabricate a Membrane Electrode Assembly (MEA). Testing on MEA performance was conducted on a Fuel Cell Station, where Open Circuit Voltage (V_OC) of 0.14 V was obtained. The results indicate that the ball milling method may produce an efficient nitrogen-doped graphene MEA electrode from graphite and melamine only. Compared with a platinum counterpart, the new composite material electrode showed soundly high current-potential characteristics and fuel conversion efficiency.

Keywords: Ball milling; fuel cells; membrane electrode assembly (MEA); oxidation reduction reaction (ORR); rotating disk electrode (RDE)

ABSTRAK

Tujuan kajian ini adalah untuk mensintesis nitrogen terdop grafinmenggunakan kaedah penggilingan bola yang mesra alam, boleh diskala dan ekonomi. Parameter yang dikaji dalam proses sintesis ialah nisbah jisim bahan mentah (grafit dan melamin) dan kelajuan penggilingan bola. Untuk menentukan struktur dan sifat sampel, nitrogen terdop grafin telah dicirikan menggunakan alatan seperti FESEM-EDX, RAMAN Spectroscopy dan XRD. Berdasarkan keputusan analisis FESEM-EDX, komposit yang terdop nitrogen menunjukkan kandungan nitrogen sebanyak ~3.5%. Nitrogen terdop grafin dikaji sebagai pengganti kepada pemangkin platinum dalam sel bahan api. Komposit pemangkin yang berbeza dinilai menggunakan Cakera Elektrod Berputar (RDE) untuk menguji prestasi ORR. Berdasarkan keputusan perbandingan prestasi ORR, pemangkin yang terbaik akan digunakan untuk memfabrikasi Pemasangan Elektrod Membrane (MEA). Pemangkin ini juga menunjukkan bacaan voltan sebanyak 0.14 V (V_OC) semasa diuji di Stesen Sel Bahan Api. Keputusan menunjukkan kaedah penggilingan bola mungkin boleh menghasilkan elektrod nitrogen terdop grafin MEA yang efisien daripada grafit dan melamin sahaja. Berbanding dengan platinum, bahan komposit elektrod yang baru ini menunjukkan ciri-ciri arus elektrik yang tinggi dan kecekapan penukaran bahan api.

Kata kunci: Cakera elektrod berputar (RDE); pemasangan elektrod membran (MEA); penggilingan bola, sel bahan api; tindak balas pengurangan pengoksidaan (ORR)

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*Pengarang untuk surat-menyurat; email nordin_sab@upm.edu.my