Sustainable biomass-derived graphitic carbon/MoS₂ nanoflower hybrid as an efficient bifunctional material for hydrogen evolution reaction and organic dye removal

Harnessing waste-derived materials for advanced functional applications offers significant environmental and technological benefits. In this study, a MoS₂ nanoflower decorated carbon hybrid was prepared via a facile hydrothermal route by dispersing pre-synthesized MoS₂ nanoflowers onto potassium hydroxide-assisted activated carbon derived from the waste tea leaves, providing a eco-friendly approach for biomass valorisation. To optimize the hybrid composition, samples were prepared with varying mass ratios of activated carbon to MoS₂ (1:1, 1:2, and 2:1). The structural, compositional, and morphological properties of the hybrids were systematically analyzed using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and FESEM characterization confirmed the uniform decoration of MoS₂ nanoflowers on the porous carbon surface, while X-ray diffraction and Raman spectroscopic studies verified the effective formation of the hybrid structure. Catalytic performance for the hydrogen evolution reaction was evaluated under acidic electrolyte conditions. Among the prepared materials, the 1:1 MoS₂/carbon hybrid exhibited the highest hydrogen evolution catalytic activity achieving a comparatively small overpotential of 274 mV corresponding to a current density of 10 mA cm⁻² and a Tafel slope value of 162 mV dec⁻¹with long-term electrochemical durability over a duration of 12 h. Furthermore, the hybrid demonstrated significant adsorption of the cationic dye Crystal Violet, achieving an adsorption capacity of 45 mg g⁻¹ after 60 minutes of contact, highlighting its potential for simultaneous energy conversion and environmental remediation applications.