Pd-catalyzed instant hydrogenation of TiO₂ with enhanced photocatalytic performance

Abstract

This facile hydrogenation strategy is based on room temperature H2 dissociation into [H] on Pd, providing a general methodology for transitional metal oxide hydrogenation under ordinary conditions for advanced photocatalysis systems.

Facile and Efficient Atomic Hydrogenation Enabled Black TiO2 with Enhanced Photo‐Electrochemical Activity via a Favorably Low‐Energy‐Barrier Pathway

“…To understand the defect changes of H–TiO 2 nanorods after the HWA treatment, the EELS spectra of H–TiO 2 treated at T wire = 1700 and 1800 °C at core and shell positions are compared (Figure S8, Supporting Information). The Ti‐L 23 edge of H–TiO 2 “shell” treated at T wire = 1700 °C shifts toward lower energy in comparison to that of the H–TiO 2 “core,” indicating the generation of Ti 3+ species . It is noted that the Ti‐L 23 edge of H–TiO 2 “shell” treated at T wire = 1800 °C shifts also toward low energy in comparison to that of the H–TiO 2 “core,” but the shift is lower than that of H–TiO 2 treated at T wire = 1700 °C, indicating lower concentration of Ti 3+ species than that of H–TiO 2 treated at T wire = 1700 °C.…”

“…Due to the simple technical configuration, the HWA is suitable for large‐scaled hydrogenation of TiO 2 for a variety of practical energy applications. The advanced features of HWA can be listed as followed: i) the most effective hydrogenation method till now (low pressure: 1 Pa, low temperature: 265 °C, and short time: 20 min); ii) one step and reproducible processing; iii) clean physical processing by using controllable and tunable flux rate of active atomic hydrogen to avoid the chemical residues; iv) general method for hydrogenation of inorganic metal oxides for broad applications; and v) large‐scaled processing for practical applications. In comparison to inefficient molecular hydrogenation and multistep solution‐based reduction approaches, HWA with controllable active atomic hydrogen can be developed to be a standard hydrogenation method for the fabrication of black TiO 2 .…”

“…The IPCE of H–TiO 2 for T wire = 1700 °C shows the best redshift of band edge (bandgap narrowing) and the best improvement of visible photoactivity. Recently, two effective and practical hydrogenation approaches using either lithium reduction or Pd‐catalyzed instant hydrogenation could achieve the maximum 2 mA cm −2 photocurrent density at 1.23 V versus RHE. In comparison to the photocurrent density of these superior hydrogenation methods, our approach achieved 2.5 mA cm −2 photocurrent density, 25% enhancement.…”

“…Very recently, Xu et al used noble metallic Pd nanoparticles to dissociate H 2 to atomic [H] (spill‐over effect) to prepare black TiO 2 . The multistep approach is efficient, but the achieved photocurrent density is limited to 2 mA cm −2 (at 1.23 V vs RHE) possibly due to the chemical residues after Pd decoration . Additionally, the underlying mechanism of atomic hydrogenation is still unclear.…”

Novel Supramolecular Photocatalyst Based on Conjugation of Cucurbit[7]uril to Non‐Metallated Porphyrin for Electrophotocatalytic Hydrogen Generation from Water Splitting

“…A number of photocatalytic systems have been developed during the past decade but those are mainly based on inorganic semiconductor materials . Titanium oxide (TiO 2 ) is one of the widely used photocatalysts because of its high chemical stability, ambient operational conditions, strong oxidizing power of holes, non‐toxicity and low cost . However, there are some drawbacks in its use as a photocatalyst as it possesses a wide energy band gap (3.2–3.4 eV) and as a result of this it absorbs the light in the UV region and a fast recombination rate between photogenerated electron‐hole pairs.…”