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The increasing demand for functional nanodevices in sustainable energy applications necessitates the development of innovative approaches. In this study, we present the fabrication and characterization of three-dimensional (3D) structures coated with titanium dioxide (TiO 2) nanorods (NRs). These novel devices are created through the integration of four distinct techniques, multi-photon lithography, post-thermal treatment, pulsed laser deposition, and an aqueous chemical growth, enabling their unique properties and functionalities in photocatalysis. The photocatalytic performance of the 3D devices is evaluated through the degradation of organic pollutants, such as methylene blue and stearic acid, showcasing their efficiency in reducing pollutant concentrations. The devices demonstrate a remarkable decomposition coefficient (k = 0.059 min − 1 ), highlighting their enhanced photocatalytic efficiency. Additionally, we propose a rapid fabrication technique using 3D holographic printing to create large-area TiO 2 -coated micro-structured photocatalytic devices at the mesoscale regime. This approach increases the active surface area, further enhancing the devices' photocatalytic capabilities. By combining additive micro-manufacturing, TiO 2 NR coating, and holographic printing, our work introduces a promising avenue for the development of advanced nanodevices with superior photocatalytic performance in sustainable energy applications. [ABSTRACT FROM AUTHOR]

We report for the first time on theredox multiphoton polymerizationof an organic–inorganic composite material, in which one ofthe components, a vanadium metallo-organic complex, initiates thepolymerization. The composite employs multiphoton absorption to self-generateradicals by photoinduced reduction of the metal species from vanadium(V) to vanadium (IV). We exploit this material for the fabricationof fully 3D structures by multiphoton polymerization with 200 nm resolution,employing a femtosecond laser operating at 800 nm, in the absenceof a photoinitiator. Nonlinear absorption measurements indicate thatthe use of an 800 nm laser initiates the photopolymerization due tothree-photon absorption of the vanadium alkoxide. The laser powerrequired to induce this three-photon polymerization is comparableto what is required for inducing two-photon polymerization in materialsusing standard two-photon absorbers, most likely due to the high contentof vanadium in the final composite (up to 50% mole). [ABSTRACT FROM AUTHOR]

Multiphoton lithography (MPL), based on multiphoton polymerization (MPP), is a powerful technique for the fabrication of 3D structures used in tissue engineering and other biomedical applications, microoptics, nanophotonics, micro‐/nanomechanics, and micro‐/nanofluidics. MPL is based on the localized polymerization/cross‐linking of photosensitive materials induced by femtosecond laser pulses. The use of an appropriate photoinitiator (PI) is required to initiate the polymerization/cross‐linking process. However, several studies have demonstrated the cytotoxicity of the PIs and their derived free radicals. The photo‐cross‐linking of a pre‐synthesized photosensitive gelatin methacrylamide (GelMA) biopolymer using an initiator‐free MPP process is reported for the first time. This is achieved by employing a femtosecond laser operating in the visible range of the spectrum (520 nm). It is demonstrated that multiphoton absorption can cause the cleavage of the polymer double bonds and induce the cross‐linking process. GelMA‐based 3D structures accurately replicating the original computer‐aided design are fabricated, and their excellent biocompatibility is demonstrated in vitro using 3D cell culture experiments with NIH‐3T3 fibroblast cells. Three‐dimensional structures based on gelatin methacrylamide are fabricated by initiator‐free multiphoton polymerization using a femtosecond laser operating in the visible range. The elimination of the toxic photoinitiator and its derived free radicals renders the approach very attractive in 3D scaffold fabrication. [ABSTRACT FROM AUTHOR]