Graphene quantum dots (GQD) with diameters as small as ∼2 nm were synthesized by an efficient chemo-mechanical technique. This involved mortar grinding and ultra-sonication as a means of mechanical energy transfer, while N-methyl-pyrrolidone and 1,2-dichlorobenzene were used for exfoliation and breakdown of graphene nanoplatelets. High resolution transmission electron microscopy images showed that the solution-based GQDs were about 2–4 nm in size, and had a crystalline lattice parameter of 0.24 nm. The technique proved useful for extracting GQDs of the desired size. XRD, Raman and FTIR spectroscopy were used to analyze the quality of the graphene structure within the GQDs. The UV responsive GQDs had a band-gap of 2.6 eV and stronger photoluminescence at 350 nm compared to lower wavelengths of laser excitation. An all-printed 2 × 2 array of memristors based on a GQD embedded polymer matrix fabricated on a flexible PET substrate showed an OFF/ON ratio of just over 7 when read at 100 mV, stable retention despite a high compliance current for ∼100 switching cycles, and a robustness of 200 bending cycles up to 1.5 cm bending diameter without compromise on resistive switching states.

The purpose to conduct this research work is to study the effect of photocatalytic degradation by developing cost-effective and eco-friendly nitrogen and tungsten (metal/non-metal) co-doped titania (TiO₂). The inherent characteristics of synthesized nanoparticles (NPs) were analyzed by Fourier transform infra-red spectroscopy (FT-IR), ultra-violet visible (UV-Vis) spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), X-ray diffraction (XRD) spectrometry, and atomic force microscopy (AFM). Co-doping of metal and non-metal has intensified the photocatalysis trait of TiO₂ nanoparticles in an aqueous medium. This co-doping of transition metal ions and modification of nitrogen extended the absorption into the visible region subsequently restraining the recombination of electrons/holes pair. The stronger light absorption in the visible region was required for the higher activity of photodegradation of dye under visible light illumination to confine bandgap energy which results in accelerating the rate of photodegradation. After efficient doping, the bandgap of titania reduced to 2.38 eV and caused the photodegradation of malachite green in visible light. The results of photocatalytic degradation were confirmed by using UV/Vis. spectroscopy and high-performance liquid chromatography coupled with a mass spectrophotometer (HPLC-ESI-MS) was used for the analysis of intermediates formed during photocatalytic utility of the work.

Titanium dioxide (TiO₂) nanoparticles have gained significant attention due to their wide-ranging applications. This research explores an approach to functionalize Niobium Nitrogen Titanium Dioxide nanoparticles (Nb-N-TiO₂ NPs) with Mentha arvensis ethanolic leaf extracts. This functionalization allows doped NPs to interact with the bioactive compounds in extracts, synergizing their antioxidant activity. While previous studies have investigated the antioxidant properties of TiO₂ NPs synthesized using ethanolic extracts of Mentha arvensis, limited research has focused on evaluating the antioxidant potential of doped nanoparticles functionalized with plant extracts. The characterization analyses are employed by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Ultraviolet–visible (UV–Vis) spectroscopy to evaluate these functionalized doped nanoparticles thoroughly. Subsequently, the antioxidant capabilities through the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays have been assessed. Within functionalized Nb-N-TiO₂, the FTIR has a distinctive peak at 2350, 2010, 1312, 1212, and 1010 cm⁻¹ with decreased transmittance associated with vibrations linked to the Nb-N bond. SEM revealed a triangular aggregation pattern, 500 nm to 2 µm of functionalized Nb-N-TiO₂ NPs. Functionalized doped Nb-N-TiO₂ NPs at 500 µg mL⁻¹ exhibited particularly robust antioxidant activity, achieving an impressive 79% efficacy at DPPH assessment; meanwhile, ferric reduction efficiency of functionalized doped Nb-N-TiO₂ showed maximum 72.16%. In conclusion, doped Nb-N-TiO₂ NPs exhibit significantly enhanced antioxidant properties when functionalized with Mentha arvensis ethanolic extract compared to pure Nb-N-TiO₂ manifested that doped Nb-N-TiO₂ have broad promising endeavors for various biomedicine applications.