Mutual effect of extrinsic defects and electronic carbon traps of M-TiO2 (M = V, Co, Ni) nanorod arrays on photoexcited charge extraction of CdS for superior photoelectrochemical activity of hydrogen production (original) (raw)
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Nanoscale Research Letters, 2013
A continuous and compact CdS quantum dot-sensitive layer was synthesized on TiO 2 nanorods by successive ionic layer adsorption and reaction (SILAR) and subsequent thermal annealing. The thickness of the CdS quantum dot layer was tuned by SILAR cycles, which was found to be closely related to light absorption and carrier transformation. The CdS quantum dot-sensitized TiO 2 nanorod array photoelectrodes were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet-visible absorption spectroscopy, and photoelectrochemical property measurement. The optimum sample was fabricated by SILAR in 70 cycles and then annealed at 400°C for 1 h in air atmosphere. A TiO 2 /CdS core-shell structure was formed with a diameter of 35 nm, which presented an improvement in light harvesting. Finally, a saturated photocurrent of 3.6 mA/cm 2 was produced under the irradiation of AM1.5G simulated sunlight at 100 mW/cm 2 . In particular, the saturated current density maintained a fixed value of approximately 3 mA/cm 2 without decadence as time passed under the light conditions, indicating the steady photoelectronic property of the photoanode.
Journal of Nanoparticle Research, 2013
In this work, we developed a new type of nanostructured photoanodes for photoelectrochemical water splitting. They are based on CdS-TiO 2 nanocomposite films, supported on conductive Ti sheets, prepared by an easy-to-achieve three-step method. It involves the production of TiO 2 nanofibers (NFs) using a controlled corrosion route of polished Ti sheets, the preparation of size-controlled CdS quantum dots (QDs) by the polyol process and the direct impregnation of TiO 2 /Ti sheets by QDs in suspension. The photoelectrochemical (PEC) properties of the resulting nanostructures were measured, using a homemade electrochemical cell illuminated with a standard Xenon lamp, and compared to those of bare TiO 2 NFs. A net enhancement of the photocurrent was observed after CdS impregnation, suggesting a low carrier recombination rate and a higher efficiency of the PEC device for solar water splitting, as the induced photocurrent is related to the electrons needed to reduce H + ions into H 2 at the cathode electrode (Pt wire). Keywords TiO 2 nanofibers CdS quantum dots CdS-TiO 2 /Ti nanocomposites Photoelectrochemical properties X-ray photoelectron spectroscopy Electron microscopy Energy conversion
International Journal of Hydrogen Energy, 2008
A CdS/TiO 2 composite photocatalyst consisting of one-dimensional CdS nanowire (NW) with a high crystallinity decorated with nanosized TiO 2 particles (NP) was fabricated by solvothermal method and sol-gel synthesis. The new configuration photocatalyst exhibited higher rate of hydrogen production than that of single CdS NW under visible light irradiation (l ! 420 nm) from water containing sulfide and sulfite ions as hole scavengers. Physicochemical properties of CdS NW/TiO 2 NP composite photocatalysts were investigated together with the effect of the mole ratio of TiO 2 and CdS for photocatalytic hydrogen production from water under visible light irradiation.
Theoretical and Experimental Chemistry, 2009
The properties of TiO 2 /CdS nanohetero structures produced by the chemical and photocatalytic deposition of CdS nanoparticles on the surface of nanocrystalline films of TiO 2 under the conditions of laser pulse photolysis were studied. It was shown that in the case of photocatalytically formed TiO 2 /CdS nanocomposites the spatial separation of the photogenerated charges between the components of the hetero structure, leading to the formation of intermediates of the photochemical transformations (Ti III centers in the TiO 2 nanoparticles and S-× radical-anions in the CdS nanoparticles), is an order of magnitude more effective.
Nanotechnology, 2016
Hydrogen fuels generated by water splitting using a photocatalyst and solar irradiation are currently gaining the strength to diversify the world energy matrix in a green way. CdS quantum dots have revealed a hydrogen generation improvement when added to TiO2 materials under visible-light irradiation. In the present paper, we investigated the performance of TiO2 nanotubes coupled with CdS quantum dots, by a molecular bifunctional linker, on photocatalytic hydrogen generation. TiO2 nanotubes were obtained by anodization of Ti foil, followed by annealing to crystallize the nanotubes into the anatase phase. Afterwards, the samples were sensitized with CdS quantum dots via an in situ hydrothermal route using 3-mercaptopropionic acid as the capping agent. This sensitization technique permits high loading and uniform distribution of CdS quantum dots onto TiO2 nanotubes. The XPS depth profile showed that CdS concentration remains almost unchanged (homogeneous), while the concentration rela...
ChemSusChem, 2014
A typographical error has been found in this Full Paper. In the caption of Figure 5, the labels for (a) and (b) were switched. The caption of Figure 5 should read: "Room temperature I-V curves of the nanorod array films with probes in contact with the surface of the films. (a) ZnO film, (b) CdS/ZnO film, and (c) CdO/CdS/ZnO film. The insets are optical microscopic images that show the tungsten probes in contact with the films." The authors and the editorial office apologize for this oversight and for any inconvenience caused.
ChemSusChem , 2018
Selective release of hydrogen from formic acid (FA) is deemed feasible to solve issues associated with the release and storage of hydrogen. Here, we present a new efficient photocatalytic system consisting of CdS nanorods (NR), Ni, and Co to liberate hydrogen from formic acid. The optimised noble metal free catalytic system employs Ni/Co as a redox mediator to relay electrons and holes from CdS-NR to the Ni and Co respectively, which also deters the oxidation of CdS-NR. As a result, a high hydrogen production activity of 32.6 mmolh-1 g-1 from the decomposition of FA was noted. Furthermore, the photocatalytic system exhibit sustained H2 production rate for 12 hours with sequential turnover numbers surpassing 4×10 3 , 3×10 3 and 2×10 3 for Co-Ni/CdS-NR, Ni-CdS-NR and CoCl2/CdS-NR respectively.
Stabilizing effect in nano-titania functionalized CdS photoanode for sustained hydrogen generation
Efficient and stable photoanode has been fabricated by the surface functionalization of the nanostructured film. For this, the surface of spray deposited CdS thin film was modified through bi-functional molecule mediated chemisorption of TiO2 nanoparticles (NP). Consequently, a systematic control over efficiency and photoanode stability against corrosion has been investigated. An in-depth quantitative analysis of the photocorrosion of these photoanodes is further studied using chronoamperometry, X-ray photoelectron spectroscopy and induced coupled plasma spectroscopy. TiO2 NP modified photoanodes show an enhanced efficiency and a stability. For photoelectrochemical (PEC) systems, the stability factor (P) has been defined for the first time based on the time dependent chronoamperometry, which clearly demonstrates that Pmodified >> Pbare. The modified photoanode shows an improved Incident Photon to Current Efficiency of 22% than the bare CdS (w8%) electrode. It gives an enhanced solar-to-hydrogen conversion efficiency of STH w 0.7% w.r.t bare CdS (0.2%) under AM 1.5G solar simulator, at 0.2 V/SCE. Improved stability of more than nine hours and enhanced efficiency is attributed to the controlled passivation of CdS surface through TiO2 NP (5 nm), and inhibition of the charge recombination. Superior and stable performance of modified photoelectrode has been validated by higher and stable hydrogen evolution over modified electrode.
Journal of Colloid and Interface Science, 2017
In this report, CdS nanoparticles have been grown on the surface of CdWO 4 nanorods via an insitu approach and their high photocatalytic ability towards dye degradation and H 2 evolution from H 2 S splitting under visible light has been demonstrated. The structural and optical properties as well as morphologies with varying amount of CdS to form CdS@CdWO 4 have been investigated. Elemental mapping and high resolution transmission electron microscopy (HRTEM) analysis proved the sensitization of CdWO 4 nanorods by CdS nanoparticles. A decrease in the PL emission of CdWO 4 was observed with increasing amount of CdS nanoparticles loading possibly due to the formation of trap states. Considering the band gap in visible region, the photocataytic study has been performed for H 2 production from H 2 S and dye degradation under natural sunlight. The steady evolution of H 2 was observed from an aqueous H 2 S solution even without noble metal. Moreover, the rate of photocatalytic H 2 evolution over CdS modified CdWO 4 is ca. 5.6 times higher than that of sole CdWO 4 under visible light. CdS modified CdWO 4 showed a good ability toward the photo-degradation of methylene Blue. The rate of dye degradation over CdS modified CdWO 4 is ca. 7.4 times higher than that of pristine CdWO 4 under natural sunlight. With increase in amount of CdS nanoparticle loading on CdWO 4 nanorods the hydrogen generation was observed to be decreased where as dye degradation rate is increased. Such nano-heterostructures may have potential in other photocatalytic reactions.