Pengaruh Waktu Ultrasonikasi terhadap Sifat Kapasitif Material Reduced Graphene Oxide sebagai Elektroda Superkapasitor

Perkembangan pengetahuan di bidang teknologi material sangat pesat dalam beberapa tahun terakhir ini. Kebutuhan akan material penyimpan energi  menjadi sebuah tantangan tersendiri. Seiring dengan ditemukannya material graphene, berkembanglah penelitian mengenai aplikasi graphene sebagai material superkapasitor karena nilai luas permukaan aktif teoritis nya mencapai 2675 m2/gr dan konduktivitas yang juga sangat baik. Reduced Graphene Oxide (rGO) adalah few atau layer graphene yang diperoleh melalui proses pengelupasan kimia dari graphite oxide. Salah satu faktor yang mempengaruhi dalam proses sintesis rGO adalah proses ultrasonikasi, dimana fungsi dari proses ini adalah mengubah graphite oxide menjadi graphene oxide, yang ditandai adanya pengelupasan (exfoliation) dari lembaran graphene sehingga menjadi lebih tipis. Dalam penelitian ini, digunakan waktu ultrasonikasi sebesar 1.5, 2, dan 2.5 jam. Pengujian karakterisasi yang dilakukan adalah pengujian XRD, SEM, Raman, dan FTIR. Dari hasil pengujian didapatkan bahwa material rGO berhasil disintesis. Kemudian dilakukan pengujian performa elektrokimia dengan menggunakan Cyclic Voltammetry (CV). Dari hasil pengujian CV didapatkan bahwa performa terbaik pada pada proses ultrasonikasi 1.5 jam, yaitu kapasitansi nya mencapai 195.15 F/gr.Kata kunci: Ultrasonikasi ; Reduced Graphene Oxide; Superkapasitor; Material Penyimpan EnergiPerkembangan pengetahuan di bidang teknologi material sangat pesat dalam beberapa tahun terakhir ini. Kebutuhan akan material penyimpan energi  menjadi sebuah tantangan tersendiri. Seiring dengan ditemukannya material graphene, berkembanglah penelitian mengenai aplikasi graphene sebagai material superkapasitor karena nilai luas permukaan aktif teoritis nya mencapai 2675 m2/gr dan konduktivitas yang juga sangat baik. Salah satu faktor yang mempengaruhi dalam proses sintesis reduced graphene oxide adalah proses ultrasonikasi, dimana fungsi dari proses ini adalah mengubah graphite oxide menjadi graphene oxide, yang ditandai adanya pengelupasan (exfoliation) dari lembaran graphene sehingga menjadi lebih tipis. Dalam penelitian ini, digunakan waktu ultrasonikasi sebesar 1.5, 2, dan 2.5 jam. Pengujian karakterisasi yang dilakukan adalah pengujian XRD, SEM, Raman, dan FTIR. Dari hasil pengujian didapatkan bahwa material reduced graphene oxide berhasil disintesis. Kemudian dilakukan pengujian performa elektrokimia dengan menggunakan Cyclic Voltammetry (CV). Dari hasil pengujian CV didapatkan bahwa performa terbaik pada pada proses ultrasonikasi 1.5 jam, yaitu kapasitansi nya mencapai 195.15 F/gr.Kata kunci: Ultrasonikasi ; Reduced Graphene Oxide; Superkapasitor; Material Penyimpan Energ

Review of the Soft Sparking Issues in Plasma Electrolytic Oxidation

A dense inner layer is highly valued among the surface coatings created through plasma electrolytic oxidation (PEO) treatment, because the PEO coating has been troubled by inherent porosity since its conception. To produce the favored structure, a proven technique is to prompt a soft sparking transition, which involves a sudden decrease in light and acoustic emissions, and a drop in anodic voltage under controlled current mode. Typically these phenomena occur in an electrolyte of sodium silicate and potassium hydroxide, when an Al-based sample is oxidized with an AC or DC (alternating or direct current) pulse current preset with the cathodic current exceeding the anodic counterpart. The dense inner layer feature is pronounced if a sufficient amount of oxide has been amassed on the surface before the transition begins. Tremendous efforts have been devoted to understand soft sparking at the metal–oxide–electrolyte interface. Studies on aluminum alloys reveal that the dense inner layer requires plasma softening to avoid discharge damages while maintaining a sufficient growth rate, a porous top layer to retain heat for sintering the amassed oxide, and proper timing to initiate the transition and end the surface processing after transition. Despite our understanding, efforts to replicate this structural feature in Mg- and Ti-based alloys have not been very successful. The soft sparking phenomena can be reproduced, but the acquired structures are inferior to those on aluminum alloys. An analogous quality of the dense inner layer is only achieved on Mg- and Ti-based alloys with aluminate anion in the electrolytic solution and a suitable cathodic current. These facts point out that the current soft sparking knowledge on Mg- and Ti-based alloys is insufficient. The superior inner layer on the two alloys still relies on rectification and densification of aluminum oxide

Review of the Soft Sparking Issues in Plasma Electrolytic Oxidation

A dense inner layer is highly valued among the surface coatings created through plasma electrolytic oxidation (PEO) treatment, because the PEO coating has been troubled by inherent porosity since its conception. To produce the favored structure, a proven technique is to prompt a soft sparking transition, which involves a sudden decrease in light and acoustic emissions, and a drop in anodic voltage under controlled current mode. Typically these phenomena occur in an electrolyte of sodium silicate and potassium hydroxide, when an Al-based sample is oxidized with an AC or DC (alternating or direct current) pulse current preset with the cathodic current exceeding the anodic counterpart. The dense inner layer feature is pronounced if a sufficient amount of oxide has been amassed on the surface before the transition begins. Tremendous efforts have been devoted to understand soft sparking at the metal–oxide–electrolyte interface. Studies on aluminum alloys reveal that the dense inner layer requires plasma softening to avoid discharge damages while maintaining a sufficient growth rate, a porous top layer to retain heat for sintering the amassed oxide, and proper timing to initiate the transition and end the surface processing after transition. Despite our understanding, efforts to replicate this structural feature in Mg- and Ti-based alloys have not been very successful. The soft sparking phenomena can be reproduced, but the acquired structures are inferior to those on aluminum alloys. An analogous quality of the dense inner layer is only achieved on Mg- and Ti-based alloys with aluminate anion in the electrolytic solution and a suitable cathodic current. These facts point out that the current soft sparking knowledge on Mg- and Ti-based alloys is insufficient. The superior inner layer on the two alloys still relies on rectification and densification of aluminum oxide