Ligand‐Assisted Co‐Assembly Approach toward Mesoporous Hybrid Catalysts of Transition‐Metal Oxides and Noble Metals: Photochemical Water Splitting

Abstract

A bottom-up synthetic approach was developed for the preparation of mesoporous transition-metal-oxide/noble-metal hybrid catalysts through ligand-assisted co-assembly of amphiphilic block-copolymer micelles and polymer-tethered noble-metal nanoparticles (NPs). The synthetic approach offers a general and straightforward method to precisely tune the sizes and loadings of noble-metal NPs in metal oxides. This system thus provides a solid platform to clearly understand the role of noble-metal NPs in photochemical water splitting. The presence of trace amounts of metal NPs (≈0.1 wt %) can enhance the photocatalytic activity for water splitting up to a factor of four. The findings can conceivably be applied to other semiconductors/noble-metal catalysts, which may stand out as a new methodology to build highly efficient solar energy conversion systems.

Surface Engineering of Spherical Metal Nanoparticles with Polymers toward Selective Asymmetric Synthesis of Nanobowls and Janus‐Type Dimers

“…An amphiphilic BCP of PEO 114 ‐ b ‐PS 288 ( M n = 35.1 kg mol −1 , Ð ( M w / M n ) = 1.14) with a thiol or dithioester group at the PS end was prepared using a reversible addition‐fragmentation chain‐transfer polymerization . The surface modification of AgNPs with the amphiphilic BCP was carried out using a solution ligand exchange method . Briefly, as‐prepared AgNPs were concentrated by centrifugation and then mixed with dithioester‐terminated PEO 114 ‐ b ‐PS 288 in dimethylformamide (DMF), a good solvent for both PS and PEO blocks.…”

Co‐Template Directed Synthesis of Gold Nanoparticles in Mesoporous Titanium Dioxide

“…The optical properties of synthesized Au@ m TiO 2 materials were examined using diffuse reflectance UV/Vis spectroscopy since the LSPR peaks of AuNPs are very sensitive to the size and aggregation of AuNPs . As shown in Figure c, a small shift of absorption peak in the range of 515–530 nm was observed for Au@ m TiO 2 with different sizes.…”

“…Synthesis and surface modifications of AuNPs : AuNPs with a diameter of 8 nm (Au8) were synthesized using a seed‐mediated growth route, whereas AuNPs with diameters of 14, 23, and 40 nm (Au14, Au23, and Au40) were prepared using the sodium citrate reduction method . The interfacial ligand exchange method was used for surface modification of Au8, whereas the solution ligand exchange method was performed for surface modifications of Au14, Au23, and Au40 .…”

“…Au‐PEO consists of pre‐synthesized AuNPs modified by thiol‐functionalized hydrophilic PEO tethers. PEO‐tethered AuNPs are chemically and structurally similar to spherical micelles of PEO 114 ‐ b ‐PS 141 , enabling the co‐self‐assembly of the two micelles in the sol–gel process . The PEO tethers stabilize AuNPs and prevent the aggregation of AuNPs under strong acidic conditions during the co‐hydrolysis of TiCl 4 and TIPO .…”

Polymer‐Assisted Co‐Assembly towards Synthesis of Mesoporous Titania Encapsulated Monodisperse PdAu for Highly Selective Hydrogenation of Phenylacetylene

“…Scheme illustrates the syntheses of PdAu@mTiO 2 . Cetrimonium bromide (CTAB) capped monodisperse PdAu nanoalloys (Pd : Au=1 : 1, mol) with a dimeter of 11.9±1.5 nm (Figures S1–S2), were firstly prepared through the co‐reduction of HAuCl 4 and Na 2 PdCl 4 . A ligand exchange with thiol‐terminated poly(ethylene oxide) (PEO 45 −SH, M n =2000 g/mol) was carried out in water then followed by dialysis in ethanol .…”