Synthesis of Platinum Nanoparticles from K2PtCl4 Solution Using Bacterial Cellulose Matrix

Platinum (Pt) nanoparticles have been synthesized from a precursor solution of potassium tetrachloroplatinate (K2PtCl4) using a matrix of bacterial cellulose (BC). The formation of Pt nanoparticles occurs at the surface and the inside of the BC membrane by reducing the precursor solution with a hydrogen gas reductant. The Pt nanoparticles obtained from the variations of precursor concentration, between 3？mM and 30？mM, and the formation of Pt nanoparticles have been studied using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), and thermogravimetry analysis (TGA). Based on X-ray diffraction patterns, Pt particles have sizes between 6.3？nm and 9.3？nm, and the Pt particle size increases with an increase in precursor concentration. The morphology of the Pt nanoparticles was observed by SEM-EDS and the content of Pt particles inside the membrane is higher than that on the surface of BC membranes. This analysis corresponds to the TGA analysis, but the TGA analysis is more representative in how it describes the content of Pt particles in the BC membrane. 1. Introduction Platinum (Pt) has attracted much attention because Pt is the best catalyst to use for a variety of specific purposes. As a noble metal, Pt has the best catalytic activity among all pure metals, especially in fuel cells [1]. Many factors affect the electrocatalytic activity of Pt particles, such as the size, distribution, and synthesis method [2, 3]. The catalytic activity of Pt is better when nanosized Pt particles are produced. A nanosized Pt catalyst that is distributed properly will result in high electrocatalytic activity [1, 4, 5]. To synthesize nanosized Pt particles, several methods have been applied, such as colloidal systems [6], reduction [7], using bacterial cellulose (BC) as a hydrophilic matrix [8], microemulsion [9], sol-gel [10], sonochemical method [11], and electrodeposition [12]. However, no one method is superior to the other methods because it depends on the final application of the catalyst used. Among these methods, the synthesis of Pt nanoparticles using the reduction method is a very simple method. This method is done by reducing the precursor solution with a reducing agent. The precursors that are most often used as a source of Pt particles are H2PtCl6 and the reducing agents, that are also commonly used, are formaldehyde [13], Lithium triethylborohydride [14], sodium borohydride [15], and ethylene glycol [16]. Yang et al. [17] have synthesized Pt nanoparticles from Pt (IV) solution, namely, H2PtCl6, into BC matrix