Influence of pH on performance of sodium phosphinate for decreasing the particle size

Abstract

To clarify the influence of pH on performance of sodium phosphinate (NaPH 2 O 2 ) for decreasing particle size of Pt nanoparticles, carbonsupported Pt nanoparticles that contained phosphorus (PÀPt/C) were synthesised by an electron-beam irradiation reduction method (EBIRM) under four different pH conditions (pH D 3, 6, 9, and 12) and under five different NaPH 2 O 2 concentrations (0.0, 0.5, 1.0, 3.0, and 5.0 mM). The relationship among pH, NaPH 2 O 2 concentration, average particle size of Pt nanoparticle, and Pt loading weight was investigated in this study. The average particle size of Pt nanoparticles was in the range of 0.8À3.4 nm and lower in the order; pH12 > pH3 > pH6 > pH9; for example, under the same NaPH 2 O 2 concentrations of 3.0 mM, the particle size of PÀPt/C prepared at pH D 12 and pH D 9 was 1.5 and 0.8 nm, respectively. In addition, Pt loading weight was also lower in the order; pH12 > pH3 > pH6 > pH9. In summary, these results indicated that the pH in the precursor solution affected the performance of NaPH 2 O 2 . These findings would be useful for controlling the particle size of monometallic Pt and Pt-based bimetallic nanoparticles supported on carbon particles for fuel cell applications.

CO Effect on the Dynamics of Platinum Nucleation/Growth Under the Liquid-Phase Synthesis of Pt/C Electrocatalysts

“…Despite the fundamental and practical significance of these processes, long-term efforts aimed at studying the mechanisms of nanostructure formation are still of limited success. Even a slight change in one of the synthesis parameters, such as the nature of the reducing agent, 11,12 temperature, 13 pH, 14 the composition of the atmosphere 15,16 and the reaction medium, 17,18 significantly affects the reaction path, the kinetics of phase formation, and, as a result, structural and morphological characteristics of the catalyst. A sizable portion of the works devoted to the search for optimal synthesis methods of Pt-based catalysts is aimed at reducing the size of the formed NPs, when paired with minimizing the dispersion of their dimensional and spatial (over the support surface) distribution.…”