Proceeding of catalytic water splitting on Cu/Ce@g-C3N4 photocatalysts: an exceptional approach for sunlight-driven hydrogen generation.

Increasing energy demands and environmental problems require carbon-free and renewable energy generation systems. For this purpose, we have synthesized efficient photocatalysts (i.e., g-C3N4, Cu@g-C3N4, Ce@g-C3N4 and Cu/Ce@g-C3N4) for H2 evolution from water splitting. Their optical, structural and electrochemical properties were investigated by UV-Vis-DRS, PL, XRD, FTIR, Raman and EIS methods. Their surface morphologies were evaluated by AFM and SEM analyses. Their chemical characteristics, compositions and stability were assessed using XPS, EDX and TGA techniques. Photoreactions were performed in a quartz reactor (150 mL/Velp-UK), whereas hydrogen generation activities were monitored using a GC-TCD (Shimadzu-2014/Japan). The results depicted that Cu/Ce@g-C3N4 catalysts are the most active catalysts that deliver 23.94 mmol g-1 h-1 of H2. The higher rate of H2 evolution was attributed to the active synergism between Ce and Cu metals and the impact of surface plasmon electrons (SPEs) of Cu that were produced during the photoreaction. The rate of H2 production was optimized by controlling various factors, including the catalyst amount, light intensity, pH, and temperature of the reaction mixture. It has been concluded that the current study holds promise to replace the conventional and costly catalysts used for hydrogen generation technologies.

Facile transfer of surface plasmon electrons of Au-NPs to Zn3V2O8 surfaces: a case study of sunlight driven H2 generation from water splitting.

For future energy perspectives, an effective way to produce H2 from water splitting is suggested using Zn3V2O8 photocatalyst as a semiconductor support. Further, to enhance the catalytic efficiency and stability of the catalyst, gold metal was deposited over the Zn3V2O8 surface by a chemical reduction method. For comparison, the Zn3V2O8 and gold-fabricated catalysts (i.e., Au@Zn3V2O8) were used for water splitting reactions. For structural and optical properties, various techniques, including XRD, UV-Vis DRS, FTIR, PL, Raman, SEM, EDX, XPS and EIS were used for the characterizations. The scanning electron microscope revealed the pebble-shaped morphology of the Zn3V2O8 catalyst. The FTIR and EDX results confirmed the purity and structural and elemental composition of the catalysts. Overall, 7.05 mmol g-1 h-1 H2 generation was observed over Au1.0@Zn3V2O8, which was ten times higher than bare Zn3V2O8. The results revealed that the higher H2 activities could be attributed to the Schottky barriers and surface plasmon electrons (SPRs). Thus the Au@Zn3V2O8 catalysts have potential to deliver higher hydrogen generation than Zn3V2O8 by water splitting.

Synergism of Co/Na in BiVO4 microstructures for visible-light driven degradation of toxic dyes in water.

In this work, we report a synergism of Co/Na in Co@Na-BiVO4 microstructures to boost the photocatalytic performance of bismuth vanadate (BiVO4) catalysts. A co-precipitation method has been employed to synthesize blossom-like BiVO4 microstructures with incorporation of Co and Na metals, followed by calcination at 350 °C. The structure and morphology of the as-prepared photocatalysts are characterized by XRD, Raman, FTIR, SEM, EDX, AFM, UV-vis/DRS and PL techniques. Dye degradation activities are evaluated by UV-vis spectroscopy, in which methylene blue, Congo red and rhodamine B dyes are chosen for comparative study. The activities of bare BiVO4, Co-BiVO4, Na-BiVO4, and Co@Na-BiVO4 are compared. To evaluate the ideal conditions, various factors that affect degradation efficiencies have been investigated. The results of this study show that the Co@Na-BiVO4 photocatalysts exhibit higher activity than bare BiVO4, Co-BiVO4 or Na-BiVO4. The higher efficiencies were attributed to the synergistic role of Co and Na contents. This synergism assists in better charge separation and more electron transportation to the active sites during the photoreaction.

Tunable sulphur doping on CuFe2O4 nanostructures for the selective elimination of organic dyes from water.

In this work, sulphur doped copper ferrites (S-CuFe2O4) photocatalysts were successfully synthesized for the first time using the facile hydrothermal method. The as-synthesized photocatalysts were characterized through XRD, Raman, TGA, FT-IR, UV-Vis-DRS, SEM, EDX and PL techniques. The results revealed that doping with sulphur has been found to be a suitable alternative that causes strain in the lattices as anions replace the oxygen from the CuFe2O4 nanostructures. Due to sulphur dopants, photocatalysts are able to efficiently trap and transfer the photoinduced charges, which readily suppress charge recombination. A UV-Vis spectrophotometer was used to monitor the degradation of selective toxic organic dyes (RhB, CR, MO, and CV) in aqueous media. The dye degradation results provide evidence for the surprisingly superior performance of S-CuFe2O4 over pristine CuFe2O4. On the basis of its efficiencies, this work can be assigned as an excellent candidate for photocatalysis science.

Growth of villi-microstructured bismuth vanadate (Vm-BiVO4) for photocatalytic degradation of crystal violet dye.

In this work, villi-microstructured Au-loaded BiVO4 photocatalysts were successfully synthesized by hydrothermal method. The as-synthesized photocatalysts were characterized by XRD, Raman, UV-Vis-DRS, PL, SEM and EDX techniques. The presence of metallic Au on the surface of Vm-BiVO4 support boosts the photocatalytic performance to degrade toxic crystal violet dye. The enhanced activities were attributed to the surface plasmon resonance (SPR) of Au which efficiently broadens the visible light response. SPR increases the electron population in Vm-BiVO4 and forms a Schottky barrier at the interface between Au and Vm-BiVO4 which enhances the separation efficiency of photoinduced charges. Various factors affecting photocatalytic degradation of crystal violet (CV) were studied to find optimum conditions. In addition, a radical trapping study indicates that ˙O2 - is the main active species in the degradation process of cationic CV dye. All photocatalytic degradation reactions were monitored by UV-Vis spectrophotometry (PerkinElmer/λ-365).