In this study, nano-TiO₂ sulfonated with 1,3-propane sultone (STiO₂) was incorporated into the chitosan (CS) matrix for the preparation of CS/STiO₂ nanocomposite membranes for fuel cell applications. The grafting of sulfonic acid (–SO₃H) groups was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis and energy-dispersive X-ray spectroscopy. The physicochemical properties of these prepared membranes, such as water uptake, swelling ratio, thermal and mechanical stability, ion exchange capacity and proton conductivity, were determined. The proton conducting groups on the surface of nano-TiO₂ can form continuous proton conducting pathways along the CS/STiO₂ interface and thus improve the proton conductivity of CS/STiO₂ nanocomposite membranes. The CS/STiO₂ nanocomposite membrane with 5 wt% of sulfonated TiO₂ showed a proton conductivity (0.035 S·cm⁻¹) equal to that of commercial Nafion 117 membrane (0.033 S·cm⁻¹). The thermal and mechanical stability of the nanocomposite membranes were improved because the interfacial interaction between the -SO₃H group of TiO₂ and the –NH₂ group of CS can restrict the mobility of CS chains to enhance the thermal and mechanical stability of the nanocomposite membranes. These CS/STiO₂ nanocomposite membranes have promising applications in proton exchange membrane fuel cells.

In this study, a one-step method was enforced for the phosphorylation of chitosan (CS) using ATMP, and later amino functionalized multiwalled carbon nanotubes (MWCNTs-NH₂) were used for the fabrication of PCS/N-MWCNTs membranes. The phosphorylation of CS and later PCS/N-MWCNTs nanocomposite membranes were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). They were also evaluated for their mechanical properties, water uptake, area swelling ratio, ion-exchange capacity (IEC), and proton conductivity. Interfacial interaction among an -NH₂ group of MWCNTs and -phosphonic acid as well as the -NH₂ group of PCS provided extra sites for proton transfer, thus improving the proton conductivity of PCS/N-MWCNTs membranes. These results revealed that the incorporation of N-MWCNTs into PCS chains lowers PCS chain mobility and ultimately improved the thermal and mechanical properties of the composite membranes. The proton conductivity of the composite membrane with 5 wt.% of N-MWCNTs at 80 °C was 0.045 S.cm⁻¹. Thus, PCS/N-MWCNTs nanocomposite membranes as a PEM can be used in fuel cells. With this advantage, the N-MWCNTs-filled hydrogen fuel cell outperforms compared to PCS filled membrane.

The rising demand for a sustainable and immaculate energy source on a global scale is fascinating regarding the usage and potential effects of green energy. Triboelectric nanogenerators have emerged as some of the major green energy sources, converting mechanical energy into electrical energy by using different electropositive and tribonegative materials. We used surface-modified multiwalled carbon nanotubes incorporated with a chitosan membrane as a tribopositive material in triboelectric nanogenerators for improved efficiency. We demonstrate that the chitosan-modified multiwalled carbon nanotube-based tribopositive material with PDMS as the tribonegative layer with a constant device size of 2 × 2 cm² produced a short circuit current density (J_sc) of 42.004 mA m⁻², an open circuit voltage (V_oc) of 244.90 volts, and a peak power density of 4.22 W m⁻², which can light up more than hundreds of LED lights. The high electrical performance of chitosan-modified multiwalled carbon nanotubes as a tribopositive material is attributed to the increased surface roughness and charge separation without causing significant charge leakage, which is produced by carbon nanotubes. Henceforth, the present work successfully introduces the use of chitosan-modified multiwalled carbon nanotubes as a tribopositive material for enhancing the TENG's output performance.