Surface Defect-Induced Site-Specific Dispersion of Pd Nanoclusters on TiO₂ Nanoparticles for Semihydrogenation of Phenyl Acetylene

Abstract

Currently, the wide application of heterogeneous noble metal catalysts is greatly limited due to their high cost and scarcity in global reserves. Thus, an effective strategy is to design highly efficient and stable catalysts with low metal loadings. In this work, highly dispersed Pd nanoclusters supported on high-surface-area TiO2 with a large number of defective Ti3+-Ov structures (Ov: oxygen vacancy) were fabricated by our developed hydrogen bubble-assisted approach, which were applied for phenylacetylene semihydrogenation to produce styrene. As-constructed supported Pd catalysts bearing a Pd loading amount of 0.2 wt % afforded a superior catalytic performance to other Pd-based catalysts with higher Pd loading amounts and commercial TiO2-supported counterparts, along with a 99% yield of styrene and a quite high turnover frequency of ∼18,930 h–1 at room temperature and ambient hydrogen pressure. Comprehensive structural characterizations, comparative catalytic experiments, and density functional theory calculations based on a Pd4 cluster model system on a defective TiO2(101) surface emphatically revealed that surface defective structures could greatly facilitate the site-specific dispersion of single Pd atoms or nanoclusters, thereby leading to the formation of electron-rich Pd0 sites favoring the semihydrogenation of phenylacetylene.

Solar driven efficient direct conversion of methane to multicarbon oxygenates

“…53 With decreasing particle size, the Ti 2p peaks of titania in the RGTX composites shi positively, implying the presence of fewer oxygen atoms in the vicinity of Ti. 54,55 Furthermore, the Ti 3+ /Ti 4+ ratio can be used to evaluate the surface O-vacancies of the catalysts. The Ti 3+ /Ti 4+ ratios of RGTX composites (Fig.…”

Possible handle for broadening the catalysis regime towards low temperatures: proof of concept and mechanistic studies with CO oxidation on surface modified Pd–TiO2

“…(b) Photo-deposition of metal occurs selectively over oxygen vacancies on the support, as they are electron-rich sites, which also helps to tune the surface electronic structure as well as stabilize and achieve high dispersion. 23–25…”

Light-Irradiated Thermal Energy-Promoted Selective Phenol Hydrogenation on Cellulose-Supported Palladium Catalyst with Green Hydrogen

“…20,21 The oxygen vacancies on oxide supports can also impact the catalytic performance positively. 22,23 Currently, it is significant to develop a sustainable system to achieve phenol hydrogenation to cyclohexanone with high catalytic activity and selectivity.…”

“…For instance, anhydrous AlCl 3 enhanced the selectivity to cyclohexanone on a Pd/C catalyst in a CH 2 Cl 2 solution by bonding carbonyl oxygen of cyclohexanone . The presence of potassium or sodium ions could promote the dissociative adsorption of phenol on a catalyst, which can also improve the selectivity to cyclohexanone. , The oxygen vacancies on oxide supports can also impact the catalytic performance positively. , Currently, it is significant to develop a sustainable system to achieve phenol hydrogenation to cyclohexanone with high catalytic activity and selectivity.…”