## 1 Introduction  
The increasing need for high-performance energy storage devices, including supercapacitors and lithium-ion batteries, has prompted extensive research efforts aiming to develop advanced electrode materials. The objective is to enhance the energy storage properties of these devices, driven by the growing demand in the industry. [1]. Porous carbon materials have garnered significant attention due to their excellent electrical conductivity, large specific surface area, and tunable pore structures, which enable efficient charge transfer and high energy storage capacity [2]. Consequently, exploring sustainable and cost-effective sources for synthesizing such materials has become imperative. In recent years, using waste materials from diverse sources for producing functional carbon-based materials has gained prominence in energy storage [3]. Blue sharks (_Prionace glauca_) are widely distributed in oceans worldwide, and historically have been intensively used as food source. However, the enormous volume of blue shark catches and their processing generates large amounts of waste (\(\sim\)100,000 tons per year, according to the FAO database [4]), which poses significant environmental challenges. This underscores the need for innovative approaches to transform this waste into valuable resources [5]. Around 10-20% of the total weight of a shark is comprised of a by-product consisting of vertebral discs and intervertebral fibrocertilage [6]. This by-product contains minerals like apatite, proteins, and glycosaminoglycans. Despite being largely unexplored, the valorization of the shark skeleton is crucial for promoting the sustainability of shark fisheries. Moreover, it could enable the recovery of valuable apatite and glycosaminoglycan fraction, which has great potential for diverse pharmaceutical applications [7; 8; 9]. Chondroitin sulfate (CS), obtained from heads and skins, is a particularly abundant glycosaminoglycan type. Its structure consists of a repeating sequence of glucuronic acid (GlcNAc) and N-acetyl galactosamine (GalNAc), linked by alternating \(\beta\)-(1\(\sim\)4) and \(\beta\)-(1\(\to\)3) glycosidic bonds [5]. Gelatine, partially hydrolyzed collagen, is a protein material that can also be obtained from connective tissues of blue sharks like cartilage and skin, which are other relevant by-products of shark filleting. This research paper investigates the potential of biocompatibility isolated from blue shark wastes as a precursor for synthesizing porous carbon materials suitable for high-performance energy storage devices. Converting these substrates into a valuable carbon-based resource is essential for waste management and sustainability. It will allow us to explore the resulting materials' performance characteristics in energy storage applications. The utilization of blue shark waste as a carbon precursor offers several advantages. Firstly, blue shark waste is abundantly available due to commercial fishing activities and can provide a consistent raw material source for large-scale production [10]. Secondly, the unique composition of blue shark waste, rich in organic compounds, polysaccharides, and proteins, presents an opportunity to engineer carbon materials with tailored structures and properties. Moreover, repurposing blue shark waste for sustainable energy storage applications can potentially reduce the ecological impact of waste disposal and promote the efficient use of marine resources. As far as the author's knowledge goes, this is the first time that blue shark chondro sulfate and gelatine have been used as precursors for producing carbon electrodes for supercapacitor applications. Several published papers used marine waste-based carbons for application as electrodes in energy storage devices, with promising results considering capacitance and retention over time. [PERSON] et al.