Shape-Controlled Synthesis of Platinum-Based Nanocrystals and Their Electrocatalytic Applications in Fuel Cells

Abstract

To achieve environmentally benign energy conversion with the carbon neutrality target via electrochemical reactions, the innovation of electrocatalysts plays a vital role in the enablement of renewable resources. Nowadays, Pt-based nanocrystals (NCs) have been identified as one class of the most promising candidates to efficiently catalyze both the half-reactions in hydrogen- and hydrocarbon-based fuel cells. Here, we thoroughly discuss the key achievement in developing shape-controlled Pt and Pt-based NCs, and their electrochemical applications in fuel cells. We begin with a mechanistic discussion on how the morphology can be precisely controlled in a colloidal system, followed by highlighting the advanced development of shape-controlled Pt, Pt-alloy, Pt-based core@shell NCs, Pt-based nanocages, and Pt-based intermetallic compounds. We then select some case studies on models of typical reactions (oxygen reduction reaction at the cathode and small molecular oxidation reaction at the anode) that are enhanced by the shape-controlled Pt-based nanocatalysts. Finally, we provide an outlook on the potential challenges of shape-controlled nanocatalysts and envision their perspective with suggestions. "Image missing"

Effect of Nanoparticle Shape on the Oxygen Reduction Reaction Activity of PtNiFe Nanocatalysts

“…In contrast, the high R m in the parameters of the synthesis of PtNiFe octahedra leads to the low yield of the octahedral shape and the higher yield of the polyhedral shape and cuboctahedral shape, as shown in Figures d and S14. It has been well established that the final shapes of alloy nanocrystals are determined by the specific bindings between the surfactant molecules and crystal surfaces, which consequently change the order of free energies for different crystallographic planes and thus their relative growth rates in the solution-phase synthesis. ,,, The above-mentioned results and discussion thus reveal that higher R m makes the increase of surfactant molecules on the {100} facets of the growth seed feasible, resulting in the formation of shapes with high coverage of the {100} facets. On the contrary, smaller R m causes the increase of the surfactant molecules on the {111} facets of growth seed, leading to the formation of shapes with the high coverage of the {111} facets.…”

“…The improvement of the efficiency and specificity of a given catalytic reaction requires finely controlled morphological parameters, which may be harnessed by synthetic routes. As a result, in the wet chemistry process, Pt-alloy nanocatalysts with different shapes were determined amid the formation of the nanocrystals confined using the surfactants and other synthetic methods. − Classical theory reveals that the surface energy of crystal facets is determined by the amount and/or type of surfactant on the crystalline phase. , In other words, the crystal facet–surfactant bindings can be delicately tuned to achieve the goal of Pt-alloy nanocatalysts with controllable shapes. For example, the ratios of oleylamine (OAm) and oleic acid (OA) are one of the most common combinations in the preparation of Pt-alloy nanostructures. − …”

Intermetallic Nanocrystals for Fuel-Cells-Based Electrocatalysis

“…This has become an inevitable trend of intermetallic electrocatalysts. On the other hand, multidimensionally anisotropic structures can provide the enhanced electron and mass transport, the improved chemical stability, as well as the multiple anchoring points with supports, thus presenting another feasible path for the enhanced electrocatalysis of intermetallics. − An important merit of this multidimensional morphological regulation is stronger interaction between nanocrystals and supports. Therefore, the multidimensionality of intermetallics has been regarded as another trend for boosting electrocatalytic performance.…”

Synergistic effect of bimetallic Pd–Pt nanocrystals for highly efficient methanol oxidation electrocatalysts

“…Pt is widely recognized as one of the primary electrocatalysts utilized in various applications. [12][13][14] To pave the way for the eventual large-scale commercialization of fuel cells, signicant attention has been dedicated to advancing Pt-based materials, aiming to develop cost-effective, highly efficient, and longlasting electrocatalysts. [15][16][17] Currently, efforts are being directed towards addressing catalytic activity by means of controlling factors such as surface structure and composition.…”