Pt Deposites on TiO2 for Photocatalytic H2 Evolution: Pt Is Not Only the Cocatalyst, but Also the Defect Repair Agent

Abstract

Pt, as a common cocatalyst, has been widely used in photocatalytic H2 evolution. However, the specific role of Pt in photocatalytic H2 evolution has not been thoroughly studied. In this paper, by employing three Pt sources with different charges (positive, negative and neutral), we systematically studied the charge effect of Pt sources on photocatalytic H2 evolution via TiO2 catalyst. According to the results of Raman, X-ray photoelectron spectroscopy (XPS), recycle experiments and photocurrent characterizations, it was found that TiO2 would produce electropositive defects during photocatalytic H2 evolution, inevitably leading to the decline of H2 production activity. Thanks to the electrostatic interaction, the electronegative Pt source not only promoted charge separation, but preferential deposited on electropositive defects, which acted as the defect repair agent, and thus resulted in the increased photocatalytic stability. This work may provide a new perspective for enhancing photocatalytic stability of hydrogen production.

Efficient electron extraction by CoS2 loaded onto anatase TiO2 for improved photocatalytic hydrogen evolution

“…Compared to noble metal cocatalysts commonly employed for anatase TiO 2 , such as metallic Pt, the photocatalytic activity improvement when loading CoS 2 is still inferior to that with metallic Pt (rH 2 = 261.1 µmol h −1 •g cat ), as seen in figure S8. Here, metallic Pt is photodeposited onto the TiO 2 host using H 2 PtCl 6 as the Pt source [84]. Despite its lower photocatalytic activity, CoS 2 is composed of low-cost, earth-abundant elements.…”

Rhus Semialata Derived Carbon Quantum Dots Decorated Pt Deposited TiO2 for Efficient Light‐Driven Hydrogen Production

“…The surfaces and interfaces that control the characteristics of nanostructured materials can be identified by XPS in terms of their underlying elemental composition.The full scan XPS spectra of A‐1 could be seen in Figure 3(a). The survey spectra of A‐1 show three intense peaks around 285, 460, and 531 eV, which correspond to C1s, O1s, and Ti2p, respectively, while the small peak around 74 eV corresponds to Pt in Pt deposited TiO 2 nanostructure, indicating that H‐CD (Figure S2, ESI) and Pt−TiO 2 nanocomposite formation was successful [44] . The C1s spectrum (Figure 3(b)) can be deconvoluted into three peaks with the binding energy values of 284.5, 286.0 and 288.6 eV that could be ascribed to C=C, C−O and O=C‐OH respectively.…”

“…The survey spectra of A-1 show three intense peaks around 285, 460, and 531 eV, which correspond to C1s, O1s, and Ti2p, respectively, while the small peak around 74 eV corresponds to Pt in Pt deposited TiO 2 nanostructure, indicating that H-CD (Figure S2, ESI) and PtÀ TiO 2 nanocomposite formation was successful. [44] The C1s spectrum (Figure 3(b)) can be deconvoluted into three peaks with the binding energy values of 284.5, 286.0 and 288.6 eV that could be ascribed to C=C, CÀ O and O=C-OH respectively. Likewise, peak at 528 eV of O1s spectrum gave three peaks on deconvolution, one at 528.0 eV, 528.5 eV and other at 529.6 eV corresponding to the presence of TiÀ O, C=O and O=C-OH bonds respectively, as observed from Figure 3(c).…”

Evaluation of Antifungal Properties of Titania P25

“…It was proposed that broadening and blue shift of peaks could be caused by an increase in the content of defects (e.g., oxygen vacancies, causing the titania lattice to shrink and, thus, shortening the length of the Ti-O bond) [46,47] and/or substitution of titanium (Ti 4+ ) by metal (e.g., Cu, Fe and Mn [50]). However, it was also proposed that platinum could repair the rupture of the Ti-O bond and, thus, reduce the blue shift of Raman peak (though in all Pt-modified samples, the blue shift was observed in comparison to the original titania) [51]. Interestingly, there are also contrary reports showing the red shift of the titania peak after modification with platinum resulting from the growth of particle size (during synthesis) [52].…”