An Effective Synthetic Process for Pt-ZnO Composite and PtZn Alloy Using Spherical Coordination Polymer Particles as Precursors

Abstract

We report size-controllable syntheses of spherical coordination polymer particles using only K 2 [Pt(CN) 4 ], Zn(NO 3 ) 2 ¢6H 2 O, and water, and their conversion to Pt-ZnO composite and PtZn alloy. This method can control both the size and surface morphology of coordination polymer particles by changing the concentrations of the starting materials without any organic solvents, surfactants, and heating treatment. For example, the increasing of [Pt(CN) 4 ] 2¹ concentration reduced the particle size and improved the smoothness of particle surface. Thermal treatment of the particles in oxidative atmosphere at 500°C results in the formation of Pt-ZnO composite. Upon further treatment in reducing atmosphere at 400°C, the composite was converted to PtZn alloy compound. After conversion to composite and alloy, the initial particle size and surface morphology were retained. Keywords: Coordination polymer particle (CPP) | PtZn alloy particle | Size-controllable synthesis Synthesis of bimetallic alloy particles with controlled size, shape, and composition have garnered considerable attention lately due to their scientific and technological applications. 1,2 These are important functional materials that are available for a wide range of applications such as magnetic materials, conductivity, catalysis, and hydrogen storage. Among these materials, Pt-based multimetallic compounds show important functions, and controlling their size and morphology, which are the critical factors that limit their utility in future applications, is particularly important. It is further recognized that the preparation of Pt-based multimetallic materials, Pt-M crystals (M = Pd, Fe, Co, Ni, etc.), was an efficient way to obtain active and durable catalysts with less consumption of expensive Pt metals.3,4 Much research effort has therefore been devoted to establish effective methods to synthesize Pt-based compounds with controllable size and/or structures.Coordination polymers (CPs) have received considerable attention lately due to their novel structures and physical and chemical properties. These materials belong to a subset of organicinorganic hybrid materials, and usually employ a central metal ion and a multitopic organic linker or a coordination complex having ambidentate ligands, such as cyanide and oxalate. CPs are attractive materials, not only for their specific properties but also for their high potential utility as precursors for the synthesis of pure inorganic materials. Various synthetic methods, such as thermolysis, hydrothermal/solvothermal methods, chemical vapor deposition synthesis, and soft-chemical growth routes have been employed to prepare various Pt-based micro/nanostructures. 515 One of the most common approaches to the synthesis of the desired multimetallic system is simultaneous decomposition or reduction of two precursor compounds. The thermal processing of CPs provides an alternate route to metal alloy and oxide materials. 1521 Here we focused on cyanide-bridged bimetallic CPs as precursors. The advantage of cyanide...

Pt–Ni/ZnO-rod catalysts for hydrogen production by steam reforming of methanol with oxygen

“…During the TPR experiments, the hydrogen is rst activated on Pt (or Ni) surface, then the active hydrogen is transferred to the surface ZnO by the hydrogen spillover, reducing it. Aer this, most of the metallic Ni (or Pt) and Zn atoms react between them to form the intermetallic NiZn or PtZn alloys, 35 The overall activity as a function of the reaction temperature is shown in Fig. 5.…”