In the present study, hybrid nanoflowers (HNFs) based on copper (II) or manganese (II) ions were prepared by a simple method and used as nanosupports for the development of effective nanobiocatalysts through the immobilization of lipase B from Pseudozyma antarctica. The hybrid nanobiocatalysts were characterized by various techniques including scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The effect of the addition of carbon-based nanomaterials, namely graphene oxide and carbon nanotubes, as well as magnetic nanoparticles such as maghemite, on the structure, catalytic activity, and operational stability of the hybrid nanobiocatalysts was also investigated. In all cases, the addition of nanomaterials during the preparation of HNFs increased the catalytic activity and the operational stability of the immobilized biocatalyst. Lipase-based magnetic nanoflowers were effectively applied for the synthesis of tyrosol esters in non-aqueous media, such as organic solvents, ionic liquids, and environmental friendly deep eutectic solvents. In such media, the immobilized lipase preserved almost 100% of its initial activity after eight successive catalytic cycles, indicating that these hybrid magnetic nanoflowers can be applied for the development of efficient nanobiocatalytic systems.

For the first time, the thermoelectric properties of cement/single-walled carbon nanotube (SWCNT) nanocomposites with over 3, 7, 14 and 28 days of hydration are reported, while a thermoelectric generator device (TEG) is fabricated utilising the material with the highest achieved power factor (PF). SWCNTs with inherent p-type semiconductor characteristics were introduced into the cementitious matrix at a water to cement (w/c) ratio of 0.5, while the Seebeck coefficient (S), electrical conductivity (σ) and PF for different SWCNT loadings were determined at different ages. The 28 day cement/SWCNT sample with 0.5 wt% loading exhibited the highest performance in terms of σ (1.59 × 10³ S m⁻¹), S (+ 1348.8 μV K⁻¹) and PF (2.89 × 10³ μW m⁻¹ K⁻²), with the PF being the highest among other carbon nanoadditive-based cement thermoelectric nanocomposites to date. The cement/SWCNT(0.5) was used for the fabrication of a thermoelectric generator (TEG) device exhibiting a maximum power output (P_max) of 5.02 μW and a power density of 5.02 mW m⁻², upon being exposed to a temperature difference (ΔT) of 50 K. Finite element (FE) simulations validated the TEG thermoelectric performance corroborating the experimental findings. The highly efficient cement/SWCNT thermoelectric nanocomposites, as well as the cement-based structural TEG device, demonstrated herein could open new avenues towards future energy efficient buildings and green construction.