Vcx 750

The precise procedure of ZnO NPs coating on PMMA was described in a previously published article [26 (link)]. Suspensions of ZnO NPs for the coating procedure were prepared in deionized water in a 0.1 wt % concentration of nanoparticles [49 ]. The PMMA samples (13 × 13 × 2 mm) were dipped in the prepared ZnO NPs suspension. The coating processes involved submerging an ultrasonic tip (Ti horn, 20 kHz, 80 µm amplitude, 70% efficiency, VCX750, Sonics & Materials Inc, Newtown, CT, USA) in the suspension, then due to vibration the tip induced cavitation for 5 min. The process temperature was stabilized at 30 °C ± 1 °C. The coated samples were washed with deionized water, dried, and then packaged in a laminar flow (laminar chamber, S@feflow 1.2 EuroCloneS.p.A., Pero (MI), Italy) for further research.

Maceration for the initial screening of the solvents was carried out for 1 h in a closed vessel placed in a thermostatically controlled bath at 50 °C with 10 mL of solvent and different solid/liquid (S/L) ratios. UAE was carried out using an ultrasonic processor (VCX750, power 750 W, 20 kHz; Sonics and Materials Inc., Newtown, CT, USA) equipped with a titanium alloy (Ti-6AI-4V) probe (13-mm diameter). Extraction was performed according to the conditions described in Section 2.4. The pulse sequence interval was 30 s ON and 30 s OFF in the whole extraction process. After extraction, the samples were diluted ten times with 50% ethanol and filtered by a 0.45 μm-pore-size cellulose membrane filter before HPLC analysis.

A mixture of PSWNT (1 mg) and flavin derivatives (0.61 mM, i.e., 0.86, 1.00, 1.13, and 1.27 mg for respective FC8, FC12, FC16, and FC20, respectively) was added to p-xylene (4 mL) which was dried over 3 Å molecular sieve (Alfa Aesar, Haverhill, MA, USA) overnight before use. The resulting mixture was subjected to 5 min bath sonication (Branson 1510, 70 W, Emerson, Saint Louis, MO, USA) for mixing, and further to 1 h tip sonication (40% power, 18.8 W/mL, probe tip diameter: 13 mm, VCX 750, Sonics & Materials, Newtown, CT, USA). During sonication, the temperatures of the sample vials were maintained at 15, 25, and 35 °C using an external water circulator (Lab Companion RW-2025G, Jeio Tech, Daejeon, Korea). Centrifugations with typical (5 and 30 kg) and optional (1 and 60 kg) g forces were conducted by using a high-performance centrifuge with a fixed angle rotor (Avanti J-26 XPI and JA-25.50, respectively, Beckman Coulter, Brea, CA, USA) at room temperature using an organic solvent-tolerant centrifugal tube (50 mL, Cat. #: 3114-0050, fluorinated poly(ethylene-co-propylene), Nalgene, Sigma-Aldrich, Saint Louis, MO, USA). 80% of the supernatant was carefully collected for further measurements. For dispersions with lower and higher flavin concentrations, 0.5 and 2.44 mM were utilized. HiPco SWNT was dispersed in a similar manner as mentioned above.

g-C₃N₄ was prepared via thermal polymerization using melamine as a precursor. Melamine powder (3 g) was heated in air to 550 °C at a heating rate of 10 °C min⁻¹. The g-C₃N₄ product was obtained after being heated at 550 °C for 5 h and naturally cooled to room temperature. t-C₃N₄ was obtained via a two-step process based on rolling-up mechanism (detailed in electronic supplementary material). Firstly, melamine (3 g) was added to 30 mL of deionized water and dispersed for 30 min using tip sonication (750 W, VCX 750, Sonics, USA). The resulting mixture was heated in a Teflon-lined autoclave at 200 °C for 12 h. After the autoclave was cooled to room temperature, a white powder was obtained. Following filtration and washing with deionized water and ethanol for three times, the white powder was ground in an agate mortar for 30 min. The ground white powder was heated under above-mentioned conditions to give the t-C₃N₄ product (heated in air to 550 °C at a heating rate of 10 °C min⁻¹ and 550 °C for 5 h).

The ultrasound irradiation process was carried out using an ultrasonic processor (Model No: VCX 750, Sonics and Materials, Inc., USA (750 W, 20 kHz)) with a titanium horn. The electrospinning process for the preparation of siloxene/PVDF piezofibers was carried out on NanoNC electrospinning instrument (Model: ESR200R2, South Korea). The X-ray diffractogram of siloxene sheets was recorded using an Empyrean X-ray diffractometer (Malvern Panalytical, UK) with Cu-Kα radiation (λ = 1.54184 Å). The Fourier transform infrared spectrum (FT-IR) was measured using a Thermo Scientific Nicolet-6700 FT-IR spectrometer. The laser Raman spectra were obtained using a Lab Ram HR Evolution Raman spectrometer (Horiba Jobin-Yvon, France, at a laser excitation source of wavelength 514 nm). The chemical state of elements present in the siloxene sheets was analyzed by an X-ray photoelectron spectrometer (ESCA-2000, VG Microtech Ltd). The surface morphology of the siloxene powders and electrospun fibers was examined using field emission scanning electron microscopy (TESCAN, MIRA3) under different magnifications with energy dispersive X-ray spectroscopy (EDS) and HR-TEM (JEM-2011, JEOL) with a CCD 4k × 4k camera (Ultra Scan 400SP, Gatan).