Khalifa University of Science and Technology

Microalgae have recently been explored for the green synthesis of metal oxide nanoparticles, offering a cost-effective alternative to conventional methods. Although effective for azo dye removal, their application in antibiotic degradation remains underexplored. In this study, microalgae-based CuO nanoflowers (NFs) were synthesised using Chlorella vulgaris extract and combined with ZnO to enhance the photocatalytic degradation of ciprofloxacin (CIP). Addressing the weak charge separation of CuO, the wide bandgap of ZnO via formation of strong p-CuO/n-ZnO heterojunctions. Microalgae-based CuO NF were produced by varying the volume ratio between CuSO 4 and Chlorella vulgaris extract at 1:1 [CuO (1Cu:1MA)], 2:1 [CuO (2Cu:1MA)], and 1:2 [CuO (1Cu:2MA)] ratios. pH edges and kinetic experiments were conducted. The most effective CuO NF was combined with ZnO to form a composite, and a central composite design with response surface methodology was used to identify optimal conditions for maximum CIP degradation efficiency. CuO (2Cu:1MA) NF exhibited the highest CIP degradation at pH 7, while CuO (1Cu:1MA) and CuO (1Cu:2MA) showed optimal performance at pH 8. The superior performance of CuO (2Cu:1MA) NF was attributed to its low bandgap, high BET surface area, and abundant surface functional groups. Kinetic data followed a pseudo-second-order model. Maximum CIP degradation of 88.3% was achieved at pH 9, a catalyst dose of 1.0 g/L, and an initial CIP concentration of 10 mg/L for CuO/ZnO (2Cu:1MA) NF. After four cycles, degradation efficiency decreased by ~10%. Overall, microalgae-based CuO nanoflowers and CuO/ZnO composites show strong potential as sustainable and effective photocatalysts for mitigating antibiotic pollution. • Organic functional groups on algae-based NFs help degradation via surface adsorption • Kinetic results reveal that adsorption plays a key role in photocatalytic degradation • RSM-CCD optimisation showed that pH and initial CIP level strongly affect degradation

Two-dimensional (2D) carbon allotropes beyond graphene, particularly graphynes, offer versatile platforms for tuning structure-property relationships in mixed sp-sp2 hybridized lattices. Here, we introduce pyrene-based α-graphyne, a novel derivative constructed via selective linker removal and hydrogen passivation, embedding extended aromatic domains while preserving the α-topology. Density functional theory calculations (PBE-GGA) confirm dynamic and thermal stability up to 2000 K, supported by phonon dispersion and ab initio molecular dynamics simulations. Mechanical analysis reveals high stiffness (Young's modulus ∼174 N m-1; shear modulus ∼71 N m-1) and a nearly isotropic elastic response. The pristine lattice exhibits Dirac-like semimetallicity. The hexagonal lattice was transformed into an equivalent orthorhombic supercell, allowing uniaxial compressive and tensile strains along armchair and zigzag directions. Under ±3% strain, a finite band gap emerges symmetrically in the meV regime. Along the zigzag direction, the gap reaches 18.6 meV (-3%) and 11.2 meV (+3%), while along the armchair direction it increases to 20.0 and 14.3 meV, respectively. For equal strain magnitudes, the larger response under armchair deformation reflects stronger modulation of pz-pz orbital overlap and strain-induced lifting of Dirac-point degeneracy. Chemical functionalization provides an additional degree of control: selective hydrogenation and fluorination at sp2 sites stabilize wide band gaps of 3.93 eV and 3.21 eV, respectively, while complete chlorination destabilizes the lattice due to steric crowding and out-of-plane distortions. Gas adsorption analysis further reveals strong, site-dependent binding for small molecules (Cl2, F2, NO, O2, and CO2), highlighting chemically active acetylenic regions. Together, these results establish pyrene-based α-graphyne as a mechanically robust, strain-tunable, and chemically responsive 2D carbon framework.