The development of mixture, alloy, and core-shell nanocatalysts with nanomaterial supports for energy conversion in low-temperature fuel cells

In this review, we present the development of Pt-based catalysts and the uses of Pt-based bimetallic and multi-metallic nanoparticles with mixture, alloy and core-shell structures for nanocatalysis, energy conversion, catalytic nanomaterials and fuel cells (FCs). The important roles of the structure, size, shape, and morphology of Pt and Pd nanoparticles, which can be engineered via chemistry and physics methods, are discussed. To reduce the high costs of FCs, Pt-based mixture catalysts can be used with cheaper base metals. Importantly, Pt-based alloy and core-shell catalysts with very thin Pt and Pt-Pd shells, Pt-noble-metal coatings or Pt-noble-metal skins can be used as Pt-based catalysts in FCs, typically low- and high-temperature proton-exchange membrane FCs (PEMFCs) and direct methanol FCs (DMFCs). On the basis of the latest scientific reports and research results, new catalytic models of the possibilities and relations of both Pt-based catalysts and supports, which are typically carbon, glasses, oxides, ceramics, and composite nanosized nanomaterials, are proposed for the further investigation of catalytic surface roles to achieve crucial improvements of Pt-based catalysts. The various applications of Pt-based catalysts with specific supports in PEMFCs and DMFCs are also discussed. The nanosystems of as-prepared Pt nanoparticles as well as Pt-based nanoparticles with various mixture, alloy, and core-shell structures are of great importance to next-generation FCs. Low-cost Pt-based mixture, alloy, and core-shell nanoparticles have been shown to have the advantages of excellently durability, reliability, and stability for realizing FCs and their large-scale commercialization. The latest trend in the use of new non-Pt alloys or new alloys without Pt but they have high catalytic activity as the same as to that of Pt catalyst has been discussed. We propose a new method of atomic deformation, and surface deformation as well as nanoparticle and structure deformation together with plastic and elastic deformation at the microand nano-scale ranges by heat treatments at high temperature can be applied for enhancement of catalytic activity, stability and durability of Pt catalyst and new non-Pt alloy and oxide catalysts in future while the characteristics of size and shape can be retained. Finally, there has been a great deal of demand to produce catalytic nanosystems of homogeneous Pt-based nanoparticles because of their ultra-high stability, long-term durability, and high reliability as well as the durable and stable nanostructures of Pt-based catalysts with carbon, oxide and ceramic supports. Such materials can be utilized in FCs, and they pose new challenges to scientists and researchers in the fields of energy materials and FCs. In addition, the importance of Pt based nanoparticle heat treatment with, and without the nanoparticle surface deformation or nuclei surface deformation is very crucial to discover a new robust Pt based catalyst for alcohol FCs. The new urgently trend of producing various novel alloy catalysts replacing Pt catalyst but similar catalytic activity is confirmed in the avoidance of the dependence of Pt-noble-metal catalyst in both the cathode and the anode of FCs. (C) 2013 Elsevier Ltd. All rights reserved.