Glycyrrhiza glabra modified ZnO nanoflakes as phytocatalysts for rapid hydrogen production via sodium borohydride-methanolysis

Abstract

The extract of Glycyrrhiza glabra (licorice root), including the active compound glycyrrhizic acid (GZA), has garnered significant interest from researchers for its many use as a food sweetener. The research effort focuses on ecologically sustainable bio-hydrogen generation technology via green synthesis methods. This research includes, for the first time, the use of Glycyrrhiza glabra extract as bio-modification material for zinc oxide nanoflakes (ZnONFs) and hydrogen generation by catalytic NaBH₄-methanolysis (SB-methanolysis) utilizing the synthesized nanoflakes. Detailed kinetic examinations were carried out on SB-methanolysis, revealing that the activation energy and lifetime of Glycyrrhiza glabra modified ZnONFs were 50.1 kJ/mol and about 134k mol H₂ (mol Zn)⁻¹, respectively. The both chemical and physical structures of Glycyrrhiza glabra modified ZnONFs and the extract were characterized, and the average particle size of the nanoflakes was revealed to be 25.70 ± 4.85 nm. Furthermore, it was understood from the SEM micrographs that average cluster size and thickness of Glycyrrhiza glabra modified ZnONFs were 8.29 ± 2.91 μm and 64.12 ± 14.37 nm, respectively. XRD data showed that ZnONFs, consisting of an average of 73.069 % Zn metal, had a hexagonal wurtzite crystal structure. In conclusion, Glycyrrhiza glabra modified ZnONFs prepared by green synthesis technique were presented in this study as an ideal phytocatalyst candidate for hydrogen production with their amazing properties and high catalytic activities.