Synthesis of waste eggshell-derived Au/Co/Zn/eggshell nanocomposites for efficient hydrogen production from NaBH4 methanolysis

Abstract

Developing new pathways to transform biological wastes into value-added products is inevitable in order to mitigate environmental pollution and providing sustainability. Utilisation of eggshell as a substrate, a naturally abandoned organic-inorganic waste, was explored in this study. Herein, Au/Co/Zn/eggshell nanocomposites were synthesised by utilizing waste eggshell as substrate. At the experimental stage, different metal combinations namely unary, binary and ternary combination of Co, Zn and Au and different ratios ranges from %10 to %50 were tested. The catalytic activity of the synthesised materials were investigated in terms of hydrogen production from NaBH4 methanolysis. The catalyst fabricated with the addition of %40 Co + %40 Zn + 3 ppm Au showed the best catalytic activity and the reaction completion time was as low as 2.4 min. The results revealed that the fabricated catalyst showed a superior catalytic activity with the maximum hydrogen production rate of 4394.6 mL/min/gcat. The obtained maximum hydrogen production rate is highly compatible with the existing literature. Different NaBH4 concentrations and catalyst concentrations were also tested to investigate the fabricated catalyst behaviour. The fabricated catalyst was also experimented in different temperatures range from 30 °C to 60 °C to determine the Arrhenius kinetics and subsequently activation energy. The activation energy was calculated to be 13.25 kJ/mol. SEM-EDX, BET, XRD and FT-IR analysis were finally performed to determine morphological and structural characterization of the superior catalyst.