Insight into growth of Au–Pt bimetallic nanoparticles: an in situ XAS study

Abstract

Au-Pt bimetallic nanoparticles have been synthesized through a one-pot synthesis route from their respective chloride precursors using block copolymer as a stabilizer. Growth of the nanoparticles has been studied by simultaneous in situ measurement of X-ray absorption spectroscopy (XAS) and UV-Vis spectroscopy at the energy-dispersive EXAFS beamline (BL-08) at Indus-2 SRS at RRCAT, Indore, India. In situ XAS spectra, comprising both X-ray near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) parts, have been measured simultaneously at the Au and Pt L-edges. While the XANES spectra of the precursors provide real-time information on the reduction process, the EXAFS spectra reveal the structure of the clusters formed in the intermediate stages of growth. This insight into the formation process throws light on how the difference in the reduction potential of the two precursors could be used to obtain the core-shell-type configuration of a bimetallic alloy in a one-pot synthesis method. The core-shell-type structure of the nanoparticles has also been confirmed by ex situ energy-dispersive spectroscopy line-scan and X-ray photoelectron spectroscopy measurements with in situ ion etching on fully formed nanoparticles.

Synergistic Effects of Plasmonic Gold and Perovskite-Type SrTiO3 for Enhanced Photocatalytic Performance of TiO2 Nanotube Arrays

“…Figure displays the intermolecular vibrational modes of the as-prepared samples, including E g , B 1g , and A 2g . Among these modes, E g at ∼145.0 cm –1 (inset spectrum) is a symmetric peak that is contributed from the O–Ti–O vibration. ,,− With the STO formation and hydrogenation, the position of the E g mode was respectively blue-shifted to 146.7 and 147.1 cm –1 for the STO/TiO 2 and H:(STO/TiO 2 ) substrates, possibly related to an increased surface tension . In this work, the Au vibration mode was not detected because of the small extent of its loading.…”

“…In addition, as shown in Figure 6c, further depositing Au on the surface of the H:(STO/TiO 2 ) generated the increase of unoccupied DOS of 5d-character with positive ΔA values of the Au L 3 -edge XANES under solar illumination. 55 Therefore, it is significant to note that solar illumination induces the existence of hot-electron transfer from plasmonic Au to H: (STO/TiO 2 ). It is believed that in situ XANES provides an appropriate account of this plasmonic hot-electron transfer between the Au and H:(STO/TiO 2 ).…”

In Situ XAS Study on Growth of PVP‐Stabilized Cu Nanoparticles

“…etc. We have also recently reported in‐situ XAS studies on the growth of Au and Pt monometallic nanoparticles and on Au@Pt bi‐metallic core‐shell type nanoparticles . However, most of the above experiments are for noble metal systems where the chances of oxidation are very rare and the growth reactions are carried out in specially designed cells and in‐situ XAS spectra were recorded in the same cell as the reaction proceeds.…”

High-Power Abiotic Direct Glucose Fuel Cell Using a Gold–Platinum Bimetallic Anode Catalyst

“…Although there is a difference in the redox potential between Au 3+ /Au 0 ( E 0 = 1.00 V) and Pt 4+ /Pt 0 (0.71 V), it does not necessarily lead to phase separation. Either the alloy formation or the phase separation depends on the power of a reducing agent. − Because we employed here sodium borohydride (NaBH 4 ) bearing a strong reducing power, reduction of the two metal ions (Pt 4+ and Au 3+ ) to the metallic state was completed prior to the electron transfer from Pt(0) or Pt 2+ to Au 3+ or Au + , thus Au–Pt alloy nanoparticles were produced.…”