Superhydrophilic and underwater superoleophobic membranes based on hierarchical TiO2 nanotubes integrated the functions of oil–water separation, flow-through photocatalysis and self-cleaning.
An environment-friendly photocatalytic strategy operated at room temperature and atmospheric pressure without using toxic precursors was used to develop high-performance MoS 2 nanoparticulate electrodes consisting of layered MoS 2 nanoparticles on anodized TiO 2 nanotubes (TiO 2 -NTs). TiO 2 -NTs were used as a substrate for MoS 2 growth because of their strong photocatalytic activity and large surface area. The photocatalysis of TiO 2 -NTs was used to reduce (NH 4 ) 2 MoS 4 precursor into MoS 2 nanoparticles. By elaborately designing the microstructures of TiO 2 -NTs, MoS 2 nanoparticles on TiO 2 -NTs demonstrates a high electrocatalytic activity for HER with an onset overpotential of -0.14 V (vs. SHE) and a Tafel slope of ~52 mV/dec, which indicates that our photocatalytic strategy is highly efficient for preparing high-activity MoS 2 nanoparticulate electrode. . 2Hydrogen is considered to be an ideal energy carrier in the future because of its cleaning, renewability and portability. 1-5 Electrochemical and photoelectrochemical water splitting is a sustainable route for hydrogen production, in which a cathode with a high electrocatalytic activity for hydrogen evolution reaction (HER) is necessary. Precious metals, such as platinum, are considered to be the best electrocatalysts for HER due to their low onset overpotential and high electrocatalytic activity. 1-8 However, the rarity and high cost prohibit the widespread use as electrocatalysts in HER. Therefore, there is growing interest in the development of efficient non-precious metal hydrogen evolution catalyst. [9][10][11][12][13][14][15][16][17][18] Molybdenum disulfide (MoS 2 ) nanoparticles with a layer structure have attracted significant attention for HER because of their excellent electrocatalytic activity and low cost. 15-30 From the practical standpoint of realizing water splitting, MoS 2 nanoparticles need to be fixed on a conductive substrate to form an electrode. Previously, MoS 2 nanoparticles were supported on the surface of Au, 17, 18 nickel foam, 19, 20 conductive glass 21-24 and carbon materials. 25-30 However, the possible application of these electrodes is hindered by their complex preparation procedures, extreme vacuum conditions and toxic precursors. Therefore, development of a sustainable strategy to fabricate MoS 2 nanoparticulate electrode is of significant importance.Herein, we proposed an environment-friendly photocatalytic strategy to develop a kind of high-performance MoS 2 nanoparticulate electrode consisting of layered MoS 2 nanoparticles on anodized TiO 2 nanotubes (TiO 2 -NTs). This photocatalytic strategy was operated at room temperature and atmospheric pressure without using toxic precursors. TiO 2 -NTs grown on Ti substrates with flexible geometry have been well-recognized to be an efficient photocatalyst because of their facile preparation method, large surface area and straight mass transfer channels. 31-33 Herein, TiO 2 -NTs were used as a substrate for the fabrication of MoS 2 nanoparticulate electrode, which provide not...
Surface wettability is of importance for electrochemical reactions. Herein, its role in electrochemical hydrogen evolution reactions is investigated using light-sensitive nanotubular TiO2 supported Pt as hydrogen evolution electrodes (HEEs). The HEEs are fabricated by photocatalytic deposition of Pt particles on TiO2 nanotubes followed by hydrophobization with vaporized octadecyltrimethoxysilane (OTS) molecules. The surface wettability of HEEs is subsequently regulated in situ from hydrophobicity to hydrophilicity by photocatalytic decomposition of OTS molecules using ultraviolet light. It is found that hydrophilic HEEs demonstrate a larger electrochemical active area of Pt and a lower adhesion force to a gas bubble when compared with hydrophobic ones. The former allows more protons to react on the electrode surface at small overpotential so that a larger current is produced. The latter leads to a quick release of hydrogen gas bubbles from the electrode surface at large overpotential, which ensures the contact between catalysts and electrolyte. These two characteristics make hydrophilic HEEs generate a much high current density for HERs. Our results imply that the optimization of surface wettability is of significance for improving the electrocatalytic activity of HEEs.
This paper describes an easy and time-saving strategy for the fabrication of heterogeneous nanotubular arrays of TiO 2 -CdS (TCHNTAs) on transparent conductive glass (FTO) and their photoelectrochemical properties. The use of transparent FTO instead of opaque Ti substrate allows incident light from the substrate side. The anodized TiO 2 nanotubular arrays were firstly detached from Ti substrate by anodization under a high voltage of 120 V and then transferred to FTO substrate using TiO 2 (P25) paste as a binder, followed by sensitization with CdS nanoparticles. After optimizing the deposition cycles of CdS nanoparticles, the TCHNTAs on FTO substrate demonstrated an enhanced photocurrent density in the Na 2 S/Na 2 SO 3 electrolyte under front-side illumination from the FTO side, which improved by ~ 21% when compared with the photocurrent density under back-side illumination from the TiO 2 -CdS side. This improvement in photoelectrochemical properties can be ascribed to the reduced charge recombination on the interface between the TiO 2 nanotubes and the CdS nanoparticles under front-side illumination. Our strategy for nanotubular transfer on transparent substrate may extend the applications of TiO 2 nanotubular arrays into other fields, such as dye-sensitized solar cells, photochromism and photocatalysis.
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