Phytomechanochemical engineering of Bi/MgO interfaces for enhanced solar hydrogen production and multicomponent antibiotic degradation.

Abstract

The development of multifunctional photocatalysts that produce renewable hydrogen (H2) while removing persistent pharmaceutical pollutants offers a promising solution for sustainable energy and water remediation. Herein, we report the first green phytomechanochemical strategy for synthesizing Bi-loaded MgO (Bi x @MgO; x = 0.2, 0.5, or 0.7 wt% MgO) photocatalysts using clove ( Syzygium aromaticum ) extract as a natural reducing/stabilizing agent combined with solvent-free mechanochemical engineering. Unlike traditional chemical methods for preparing Bi-modified MgO, the current method combines phytochemical processes of Bi3+ reduction and a mechanochemical process for dispersing Bi onto MgO, forming the Bi/MgO interface without post-synthesis annealing. Bi addition leads to modification of both optical and electronic properties of MgO with a simultaneous increase of defect-mediated charge transfer. Bi0.7@MgO showed a decreased band gap of 2.78 eV and more efficient charge separation than that of pure MgO. Under optimal conditions Bi0.7@MgO exhibited a hydrogen production rate of 33.44 mmol g-1 h-1 when illuminated with solar light. The same photocatalyst also removed 98-99% of amoxicillin, cefixime, azithromycin, and ciprofloxacin under simulated solar light irradiation while maintaining high recyclability over six consecutive cycles.

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