Carbon is the fourth most abundant element in the universe. Among all carbon allotropes, carbon nanotube (CNT) with a cylindrical tube structure becomes an attractive carbon nanomaterial due to its unique physical and chemical properties. The typical gas sources that are usually used in CNT synthesis are mostly hydrocarbons, e.g., alcohol, methanol, methane (CH4), ethylene (C2H4), acetylene (C2H2), propane (C3H8), and cyclohexane (C6H12). Unfortunately, those carbon precursors are not environmentally friendly due to their origin from fossil fuels. Considering its continuity production, utilizing “green” alternatives and inexpensive materials will be more promising for industrial-scale production. Biogas is one of the alternative ideas as a carbon precursor in the process of CNT synthesis. Biogas consists of 40–60% methane (CH4), 40–60% carbon dioxide (CO2), and traces of nitrogen (N2), oxygen (O2), hydrogen sulfide (H2S), hydrogen (H2), and ammonia (NH3). The most commonly used to produce CNT is CH4 through chemical vapor deposition (CVD). CVD is the most expectant and scalable method for future power and electronic devices with its economical and straightforward friendly design.

<p><em>Carbon nanotubes</em> (CNT) menjadi salah satu material unggul teknologi nano yang membawa banyak keuntungan karena memiliki sifat kimia dan mekanik yang baik. Hal ini menjadikan CNT dimanfaatkan di berbagai aplikasi <em>nano-device </em>ataupun material komposit. Beberapa metode yang sering digunakan untuk menumbuhkan CNT adalah deposisi uap kimia (<em>Chemical Vapor Deposition</em>), laser ablasi dan <em>arc discharge</em>. Kebanyakan sumber prekursor karbon dalam sintesis CNT diambil dari bahan bakar fosil yang memiliki kelemahan bahan tidak bisa diperbaharui dan menghabiskan biaya yang mahal. Limbah bahan alam atau hasil biomassa dapat menjadi alternatif bahan baku pembuatan CNT yang membawa keunggulan biaya murah, ketersediaan melimpah, dan hemat energi, contohnya seperti limbah tempurung kelapa yang mengandung unsur karbon tinggi. Tempurung kelapa telah dilaporkan sebagai salah satu bahan baku potensial produksi CNT. Aplikasi CNT dalam polimer komposit contohnya penggabungan dengan polimida. Keunggulan polimida adalah sifat mekaniknya yang sangat baik, stabilitas termal, dan ketahanan kimia. Namun, polimida memiliki kelemahan dalam konduktivitas termal yang rendah. Penambahan CNT ke dalam polimida dapat meningkatkan konduktivitas termal sehingga meningkatkan kinerja polimer tersebut. </p><p><strong>Synthesis of Coconut-Shell Waste-based Carbon nanotubes (CNT) and Its Application in Polymer Composite Polyimide-CNT Fabrication: Review. </strong><em>Carbon nanotubes (CNTs) have become one of the excellent materials for nanotechnology which brings many advantages because of their good chemical and mechanical properties, inducing CNTs to be used in various nano-device applications or composite materials. Some of the methods commonly used to grow CNTs are chemical vapor deposition, laser ablation, and arc discharge. Most sources of carbon precursors in CNTs synthesis are taken from fossil fuels which have the disadvantages of non-renewable materials and high cost. Natural waste or biomass products can be an alternative raw material for CNTs production which brings the advantages of low cost, abundant availability, and energy-saving, for example, such as coconut shell waste which contains high carbon elements. Coconut shell has been reported as one of the potential raw materials for CNT production. CNT applications in composite polymers are for example collaboration with polyimides. The advantages of polyimides are their excellent mechanical properties and chemical resistance. However, polyimides have a disadvantage in their low thermal conductivity. The addition of CNT into polyimides can increase its thermal conductivity enhancing polyimide performance.</em></p><p align="center"> </p>