Electronic Tuning of Gold Nanoparticle Active Sites for Reduction Catalysis

Abstract

Electronic tuning of active sites in heterogeneous catalysis with organic ligands remains challenging since the ligands are often bound to the most active sites on the catalysts’ surfaces. In this work, gold nanoparticles, which are on average less than 2 nm in diameter, are synthesized with strongly binding thiol and phosphine ligands and have measurable quantities of accessible sites on their surfaces in both cases. Triphenylphosphine (TPP) is used as the phosphine ligand, while triphenylmethyl mercaptan (TPMT) serves as the thiol ligand. Phosphines are chosen because they are electron-donating ligands when bound to Au, and thiols are selected because they are electron-withdrawing on the Au surface. X-ray photoelectron spectroscopy (XPS) results show differences in the Au 4f binding energies between the TPP- and TPMT-bound Au nanoparticles. Fourier transform infrared spectroscopy (FTIR) measurements of bound CO indicate that the TPP-bound Au nanoparticles are more electron-rich than the TPMT-bound Au nanoparticles. The number of binding sites on the surface is quantified using 2-naphthalenethiol titration experiments. It is observed that the number of binding sites on the thiol and phosphine-bound Au nanoparticles is similar in both cases. The Au nanoparticles are used for three different reactions: resazurin reduction, CO oxidation, and benzyl alcohol oxidation. For both CO oxidation and benzyl alcohol oxidation, which are performed with the ligands attached, TPP- and TPMT-bound nanoparticles are both catalytically active. However, for resazurin reduction, the TPMT-bound Au nanoparticles are not active, while the TPP-bound Au nanoparticles are catalytically active. These results illustrate that the catalytic activity can be tuned using bound organic ligands with different electronic properties for reduction reactions using Au nanoparticle catalysts.

Unraveling the transformative pathways of Au-NHC and Au-alkynyl complexes and bridging the gap between molecular and nanoscale gold systems

“…With their distinctive chemical and catalytic properties, gold compounds have been the subject of extensive research in recent decades. 1–70 Research in this field employs either well-defined gold complexes 2,12,52–57,59–70 or gold particles ranging from subnanometer to macroscale with a well/poorly defined structure, 1,3–11,14,24,28–37,39,45,49 each demonstrating unique catalytic behavior. 1–70…”

“…1–70 Research in this field employs either well-defined gold complexes 2,12,52–57,59–70 or gold particles ranging from subnanometer to macroscale with a well/poorly defined structure, 1,3–11,14,24,28–37,39,45,49 each demonstrating unique catalytic behavior. 1–70…”

“…4,7,8,37 Various gold complexes and nanoparticles are now easily accessible from readily available sources. 1–70 The distinct advantage of this developed method lies in its sequential approach, allowing the precise procurement of specific gold forms. 1–8…”

Electron Structure Tuned Oxygen Vacancy‐Rich AuPd/CeO2 for Enhancing 5‐Hydroxymethylfurfural Oxidation

“…[16,17] For instance, Nigra and co-worker found that employed the electrondonating ligand of phosphines or electron-withdrawing of thiol ligand as ligands can successfully regulate the electronic tuning of Au active sites, and showing the different catalytic ability for oxidation and reduction reaction. [18] Research shown that the strongly metal-support interaction was an important strategy to improve the electron state of Au catalyst. [19] Chu et al reported that CeMnO 3 perovskite supported Au nanoparticles (NPs) shown the higher oxidation ability in comparison with CeO 2 and Mn 3 O 4 , suggesting that Mn site metal in the CeMnO 3 raised the d-band center of Au and formatted the high content of metallic Au 0 species, thus strengthened the adsorption of substrate for catalyst.…”

Ligand Decomposition Differences during Thermal Sintering of Oleylamine-Capped Gold Nanoparticles in Ambient and Inert Environments: Implications for Conductive Inks

“…Gold nanoparticles (GNP) have garnered significant attention in contemporary nanotechnology, underpinned by their unique properties such as easy solution processability, robust plasmonic absorption, and efficient light scattering. , This attention is substantiated by their varied applications in realms like photothermal therapy, , thermoelectrics, , photovoltaics, , and photocatalysis. − Traditionally, the gold nanoparticles are synthesized as a colloidal suspension, commonly referred to as “ink”, which encompasses ligands to prevent agglomeration and maintain the desired nanoparticle size and shape. Numerous ligands have been used in gold nanoparticle synthesis such as short-chain thiols, , amines, , and phosphine, and different ligand types will help to fulfill different applications.…”