Small (<5 nm), Clean, and Well‐Structured Cubic Platinum Nanoparticles: Synthesis and Electrochemical Characterization

Abstract

Shape‐controlled metal nanoparticles are significantly improving the electrocatalysis of many relevant reactions. By controlling the shape of nanoparticles, it is possible to engineer their surface to exhibit a preferential structure. However, to facilitate the incorporation of shaped nanomaterials into practical electrochemical devices, it is indispensable to overcome limitations caused by their large particle size (typically &gt;5 nm). For practical applications, nanoparticles must have a size lower than 5 nm with a clean surface to decrease costs and provide a sufficiently large specific surface area. This is a major challenge that has remained unexplored up to now. Herein, we present the synthesis and electrochemical characterization of 3–5 nm, with well‐defined cubic Pt nanoparticles supported on carbon. The electrochemical characterization of the nanoparticles evidences the existence of a preferential {100} and clean structure (within about 40 % of {100} terrace surface).

Controllable Surfactant‐free Synthesis of Colloidal Platinum Nanocuboids Enabled by Bromide Ions and Carbon Monoxide

“…Figure 5a shows the electrochemical features on Pt nanocubes, proving the nanoparticles are mainly enclosed by Pt {100} facets. [31] The specific electrochemical surface areas are 40.0, 37.5, 20.3 m 2 g À 1 for nc-Pt 3 , nc-Pt 5 and nc-Pt 7 nanocubes, respectively, being consistent with the obtained particle sizes. In addition to VXC-72R carbon support, ordered mesoporous carbon (CMK) was able to support Pt NCs.…”

“…All the three samples had the average length‐to‐width aspect ratio around 1.2, suggesting that the majority were in the cubic shape. Figure 5a shows the electrochemical features on Pt nanocubes, proving the nanoparticles are mainly enclosed by Pt{100} facets [31] . The specific electrochemical surface areas are 40.0, 37.5, 20.3 m 2 g −1 for nc‐Pt 3 , nc‐Pt 5 and nc‐Pt 7 nanocubes, respectively, being consistent with the obtained particle sizes.…”

“…[16][17] Figure 4a shows the Pt NCs of nc-Pt 3 with the edge length of 3.5 nm, which is the smallest NCs among the reported results (Table 1). [31] Figure 4b and c show the formation of large Pt cubes of 5.5 and 7.1 nm but with wide size distribution (Figure 4d) at high concentration of Pt 4 + . All the three samples had the average length-to-width aspect ratio around 1.2, suggesting that the majority were in the cubic shape.…”

“…To evaluate the percentage of Pt{100} terrace sites, electrochemical adsorption and desorption of Ge was conducted as shown in Figure 5b and Figure S5 via the approach applied by Feliu et al. [32][33] The results show that the percentages of Pt {100} terrace sites on nc-Pt 3 , nc-Pt 5 , and nc-Pt 7 are 27.7, 28.3 and 34.2 %, respectively, slightly less than 40 % reported by Antoniassi et al, [31] probably due to more surface defects on our as-prepared nanocubes. However, the calculated percentages of Pt{100} terrace sites are much higher than that on commercial Pt nanoparticles (4.6 % Pt{100} in Figure S5), suggesting that the nanocubic morphology was formed definitely.…”

Ultrasmall, Coating-Free, Pyramidal Platinum Nanoparticles for High Stability Fuel Cell Oxygen Reduction

“…To the best of our knowledge, the goal of ultrasmall, preferentially shaped, Pt nanoparticles has never been accomplished in one-pot water-based, fast, and easily scalable synthesis. Only one recent report has achieved sub-5 nm carbon-supported Pt nanocubes displaying a high percentage of {100} facets, obtained through reshaping of spherical NPs once deposited on carbon support . This promising report further emphasizes the need to develop simple synthetic methods that control the growth and the shape of the nanomaterials directly in solution to craft the materials on the application requirements.…”