Methylene Blue Dye as Photosensitizer for Scavenger-Less Water Photo Splitting: New Insight in Green Hydrogen Technology

In this study, hydrogen generation was performed by utilizing methylene blue dye as visible-light photosensitizer while the used catalyst is working as a transfer bridge for the electrons to H+/H2 reaction. Silica NPs-incorporated TiO2 nanofibers, which have a more significant band gap and longer electrons lifetime compared to pristine TiO2, were used as a catalyst. The nanofibers were prepared by electrospinning of amorphous SiO2 NPs/titanium isopropoxide/poly (vinyl acetate)/N, N-dimethylformamide colloid. Physicochemical characterizations confirmed the preparation of well morphology SiO2–TiO2 nanofibers with a bandgap energy of 3.265 eV. Under visible light radiation, hydrogen and oxygen were obtained in good stoichiometric rates (9.5 and 4.7 mL/min/gcat, respectively) without any considerable change in the dye concentration, which proves the successful exploitation of the dye as a photosensitizer. Under UV irradiation, SiO2 NPs incorporation distinctly enhanced the dye photodegradation, as around 91 and 94% removal efficiency were obtained from TiO2 nanofibers containing 4 and 6 wt% of the used dopant, respectively, within 60 min

Carbon Nanofibers-Sheathed Graphite Rod Anode and Hydrophobic Cathode for Improved Performance Industrial Wastewater-Driven Microbial Fuel Cells

Carbon nanofiber-decorated graphite rods are introduced as effective and low-cost anodes for industrial wastewater-driven microbial fuel cells. Carbon nanofiber deposition on the surface of the graphite rods could be performed by the electrospinning of polyacrylonitrile/N,N-Dimethylformamide solution using the rod as nanofiber collector, which was calcined under inert atmosphere. The experimental results indicated that at 10 min electrospinning time, the proposed graphite anode demonstrates very good performance compared to the commercial anodes. Typically, the generated power density from sugarcane industry wastewater-driven air cathode microbial fuel cells were 13 ± 0.3, 23 ± 0.7, 43 ± 1.3, and 185 ± 7.4 mW/m2 using carbon paper, carbon felt, carbon cloth, and graphite rod coated by 10-min electrospinning time carbon nanofibers anodes, respectively. The distinct performance of the proposed anode came from creating 3D carbon nanofiber layer filled with the biocatalyst. Moreover, to annihilate the internal cell resistance, a membrane-less cell was assembled by utilizing a poly(vinylidene fluoride) electrospun nanofiber layer-coated cathode. This novel strategy inspired a highly hydrophobic layer on the cathode surface, preventing water leakage to avoid utilizing the membrane. However, in both anode and cathode modifications, the electrospinning time should be optimized. The best results were obtained at 5 and 10 min for the cathode and anode, respectively