Hydrothermal Synthesis of Platinum Group Metal Nanoparticles

Abstract

Abstract. A novel route for the synthesis of platinum group metal nanoparticles has been reported. The synthesis is based on the addition of tetramethylammonium hydroxide (TMAH) to the aqueous PtCl 4 , IrCl 3 or Rh(NO 3 ) 3 solution followed by the hydrothermal treatment of these precipitation systems at 160 ºC. The mean size of nanoparticles was 9.2 nm for platinum, 21 nm for iridium, and 28 nm for rhodium. The average crystallite size was estimated at 7.4 nm for platinum, 3.1 nm for iridium and 3.5 nm for rhodium. The possible mechanism of platinum group metal nanoparticles formation is briefly discussed. (doi: 10.5562/cca1856)

The influence of platinum(IV) ions on the formation of iron oxides in a highly alkaline medium

“…4) and at 580 cm À1 in the spectrum of samples PtG2-16h and PtG2-24h (Fig. 5) confirmed the presence of Fe 3 O 4 in the said samples [58][59][60][61]. The above mentioned Fe 3 O 4 IR band is dominant in the spectrum of sample PtG1-72h (Fig.…”

The effect of iridium(III) ions on the formation of iron oxides in a highly alkaline medium

“…The infrared spectrum of ␣-Fe 2 O 3 depends on the shape of particles [58,59] and the positions of these bands match closely those in the spectra of pseudocubic ␣-Fe 2 O 3 particles [59][60][61], which is in line with the FE-SEM images of corresponding samples (see Section 3.4,. A broad band with the minimum at 580 cm −1 indicates the presence of only Fe 3 O 4 as a single iron oxide phase [46,62,63], which tallies with the XRD and Mössbauer measurements.…”

“…In the absence of the platinum group metal ions Fe 3+ ions have not been reduced and only Fe(III) oxides have been formed [17,19,20,27,28]. On the other hand, in the presence of even a small amount (1 mol% or less) of platinum group metal ions ␣-FeOOH has been completely transformed to Fe 3 O 4 [18,[46][47][48][49]. On the basis of these observations, it can be concluded that the platinum group metals act as catalysts for the transformation ␣-FeOOH → Fe 3 O 4 in the presence of TMAH.…”

“…Formation of Fe 3 O 4 has been observed only in the case of the platinum group metal cations (ruthenium, palladium, platinum and rhodium) [18,[46][47][48][49], well known for their excellent catalytic properties. In the absence of the platinum group metal ions Fe 3+ ions have not been reduced and only Fe(III) oxides have been formed [17,19,20,27,28].…”

“…In our previous studies [17][18][19][20][46][47][48][49] we have investigated the influence of various metal cations on the formation of iron oxides in a highly alkaline medium in the presence of TMAH. Formation of Fe 3 O 4 has been observed only in the case of the platinum group metal cations (ruthenium, palladium, platinum and rhodium) [18,[46][47][48][49], well known for their excellent catalytic properties.…”