Unveiling the marine Sargassum horneri material for energy and active sensor devices: Towards multitasking approaches

The quest for a future with greater environmental sustainability has led to a rising focus on investigating innovative methods for energy production and storage. However, marine invasions have steadily increased over the past two centuries, necessitating innovative approaches for the remediation and preservation of oceanic environments. Especially, Sargassum horneri (S. horneri) is a brown algae that causes massive floating macroalgal blooms along the coasts of East Asia. Given these facts, this paper develops high-performance triboelectric nanogenerator (TENG), and electrode material for both supercapacitor and water-splitting devices based on S. horneri. The TENG device, constructed using S. horneri coastal bio-waste collected from Jeju Island, yields impressive results. The output current, voltage and power generated by the S. horneri-based triboelectric nanogenerator (SH-TENG) is around 47 µA, 775 V, and 2880 µW, respectively. The electrochemical analysis of carbon derived from S. horneri reveals an excellent electrode capacitance of 225 F/g at 2.5 mA. Constructing the symmetric supercapacitor device using S. horneri-derived carbon, which shows excellent energy and power densities around 14.85 Wh/kg and 972.22 W/kg, with remarkable cyclic stability of 81.3 % for 5000 GCD cycles at 7 mA. On the other hand, the developed S. horneri electrode demonstrated much-improved activity towards water splitting application, exhibiting overpotentials of 0.101 V and 0.198 V for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at an applied current density of 20 mA/cm², respectively. The fabricated sample also demonstrated the lowest Tafel values towards HER (119 mv/dec) and for OER (109 mv/dec). Finally, the time series analysis (TSA) technique was employed for modeling and prediction of capacity retention of the SH//SH supercapacitor and electrochemical potential (E) of SH/NF║SH/NF cell. In both cases, the mean squared error between experimental and predicted data was very small, suggesting the TSA is a powerful statistical technique to model and predict the vial features of the electrochemical devices. Overall, these results suggest that S. horneri-derived carbon presents a viable alternative in the realm of energy storage and harvesting, promising sustainable technological advancements.