Investigation of Dunaliella salina microalgae as an effective dual-function material for hydrogen production and supercapacitor applications

Abstract

Today, population growth, industrialization and economic growth increase the consumption of fossil fuels to meet the energy demand. The scarcity of fossil fuels and the harmful gases they generate increase the interest in renewable energy sources. One of these sources is hydrogen energy, which is plentiful in nature and has no negative environmental effects. Sodium borohydride (NaBH4) is a good source of hydrogen, but a catalyst must used for methanolysis. Besides producing energy, it is also important to store it. Supercapacitors are a good alternative to energy storage elements due to their outstanding advantages. In this work, Dunaliella salina (DS) microalgae were used as substrate to synthesize activated carbon for the first time to develop materials that can operate both as a catalyst and an electrode material for supercapacitors. The activated carbon was obtained by carbonization and activation and the taguchi experimental approach was used to minimize the number of experiments. The best hydrogen production rate (HPR) result for DS-9 catalyst with 0.10 g catalyst and 0.25 g NaBH4 at ambient temperature of 60 °C was determined to be 13,085 mL min−1gcat−1. The material with the best HPR value was then used as the electrode material for supercapacitor design. The specific capacitance value for 1 A/g was determined using galvanostatic charge-discharge (GCD) curves to be 216 F/g. In addition, the produced supercapacitor has an energy density of 13.80 W h/kg at a power density of 480 W/kg. The results indicate that the ecologically friendly and cost effective bifunctional materials produced can be used both in reuse of organic wastes and in catalyst and supercapacitor applications.