CONDUCTIVITY AND THERMAL STABILITY OF SOLID ACID COMPOSITES CsH2PO4/NaH2PO4/SiO2

Abstract

Solid acid composites CsH 2 PO 4 /NaH 2 PO 4 /SiO 2 with different mole ratios of CsH 2 PO 4 and NaH 2 PO 4 to SiO 2 were synthesized and characterized. Preliminary infrared measurements of CsH 2 PO 4 and its composites indicated that hydrogen bonds breaking and formation were detected between 1710 to 2710 cm -1 , while the rotation of phosphate tetrahedral anions occurred between 900 and 1200 cm -1 . The superprotonic transition of CsH 2 PO 4 /NaH 2 PO 4 /SiO 2 composite was identified at superprotonic temperatures between 230 and 260 °C, under atmospheric pressure. This study reveals higher conductivity values for composites with higher CsH 2 PO 4 (CDP) content. Solid acid composite CDP 613 appeared as the composite with the highest conductivity that is 7.2 x 10 -3 S cm -1 at 230 °C. Thermal stability of the solid acid composites such as temperature of dehydration, melting and decomposition were investigated. The addition of NaH 2 PO 4 lowers the dehydration temperature of the solid acid composites.Keywords: solid acid, conductivity, thermal analysis, caesium dihydrogen phosphate, fuel cell Abstrak Asid pepejal komposit CsH 2 PO 4 /NaH 2 PO 4 /SiO 2 dengan nisbah mol CsH 2 PO 4 kepada SiO 2 dan NaH 2 PO 4 kepada SiO 2 yang berbeza telah disintesis dan dicirikan dalam ujikaji ini. Pencirian awal sinar inframerah menunjukkan bahawa pemecahan dan pembentukan ikatan hidrogen dikesan antara 1710 cm -1 dan 2710 cm -1 , manakala putaran anion tetrahedron fosfat berlaku diantara 900 cm -1 dan 1200 cm -1 . Fasa peralihan berkonduktiviti tinggi bagi asid pepejal komposit CsH 2 PO 4 /NaH 2 PO 4 /SiO 2 telah dikenal pasti antara suhu 230 hingga 260 °C, di bawah tekanan atmosfera. Nilai kekonduksian proton adalah lebih tinggi bagi komposit yang mempunyai kandungan CsH 2 PO 4 (CDP) yang lebih tinggi. Asid pepejal komposit CDP 613 telah muncul sebagai komposit dengan kekonduksian tertinggi iaitu 7.2 x 10 -3 S cm -1 pada suhu 230 °C. Kestabilan terma asid pepejal komposit seperti suhu dehidrasi, takat lebur dan penguraian telah dikenal pasti melalui analisis termogravimetri dan kalorimeter imbasan perbezaan. Penambahan NaH 2 PO 4 merendahkan suhu dehidrasi asid pepejal komposit.Kata kunci: asid pepejal, kekonduksian, analisa terma, sesium dihidrogen fosfat, sel bahanapi Introduction Solid acids emerged as a potential solid electrolyte for fuel cell applications due to its high proton conductivity, also known as superprotonic conductivity as the conductivity values increases by 2 to 3 orders of magnitude at intermediate temperatures between 100 to 250 °C, accompanied by phase transition [1]. Solid acids are defined by the basic chemical formula M a H b (XO 4 ) c where M is a monovalent or divalent metal cation, XO 4 is a tetrahedral oxyanion, and a, b, c are integers [2]. Solid acids caesium dihydrogen phosphate, CsH 2 PO 4 (CDP) and caesium

A synergistic approach to achieving high conduction and stability of CsH2PO4/NaH2PO4/ZrO2 composites for fuel cells

“…We also found that the conductivity of solid acid composites at a high temperature slightly increases due to the hydrophobicity and surface area of ZrO 2 . 40 The conductivity of CDP/SDP/ZrO 2 increased to 1.5 orders of magnitude in the LT region and high temperature which was due to the structural disorder and deformation of the cation shape of ZrO 2 . 31 Furthermore, we investigated the time dependence of the ionic conductivity of CDP, SDP, and 8CDP/1SDP/1ZrO 2 under high hermetically confined conditions.…”

Synthesis of BaSnO3 as a Highly Dispersed Additive for the Preparation of Proton-Conducting Composites

“…In addition, comprehensive studies of composite systems based on a number of acidic salts of Me x H y (AO 4 )z: MeHSO 4 (Me = Cs, Rb, K), Cs 5 H 3 (SO 4 ) 4 , (NH 4 ) 3 H(SO 4 ) 2 , CsH 2 PO 4 , and silicon dioxide with a different specific surface area (10. . .580 m 2 /g) were carried out [44][45][46][47][48].…”