• PDF / 543,929 Bytes
• 5 Pages / 595.32 x 841.92 pts (A4) Page_size
• 3 Downloads / 183 Views

DOWNLOAD

REPORT

---

doi: 10.1007/s40242-020-9276-1

Introduction of H2SO4 and H3PO4 into Crystalline Porous Organic Salts(CPOS-1) for Outstanding Proton Conductivity WANG Yuxia1, YAN Tingting1,2 and BEN Teng1* 1. Department of Chemistry, Jilin University, Changchun 130012, P. R. China; 2. Shandong Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, P. R. China Abstract To improve the proton conduction of crystalline porous organic salts(CPOS-1), H2SO4 and H3PO4 were introduced into the channel to obtain H 2SO4@CPOS-1 and H3PO4@CPOS-1. Compared to CPOS-1, the proton conductivities of H2SO4@CPOS-1 and H3PO4@CPOS-1 increased two orders of magnitude and one order of magnitude at 303 K and 100% RH, respectively. It can be attributed to the increasing concentration of the protons, which dissociates from the acids. Keywords Proton conductivity; Crystalline porous organic salt; H2SO4; H3PO4

1

Introduction

The proton exchange membrane fuel cell(PEMFC) has drawn wide attention due to its high energy density and low pollution[1,2]. The performance of electrolyte species directly affects the performance of PEMFCs. Recently, porous materials, such as metal organic frameworks(MOFs)[3,4], covalent organic frameworks(COFs)[5―7], and crystalline porous organic salts(CPOSs)[8] have been applied to proton conduction. Owing to high stability and definite structure, these porous materials exhibit excellent performance in proton conduction, which make them potential candidates as proton conductors[9―11]. As we all know, the concentration and mobility of protons are the two key factors that impact the conduction of protons[12,13]. Inspired by this, introducing an additional source of protons, such as imidazole[14], histamine[15], sulfuric acid[16], or phosphoric acid[17] to host frameworks facilitates an increase in proton concentration, and therefore may increase the proton conductivity to a certain extent. Alternatively, modification of the host framework by grafting ―SO3H could also increase the proton conduction[18―21]. According to a recent report[8], CPOS-1 is a crystalline porous organic salt with a one-dimensional polar channel formed from tetrakis(4-sulfophenyl)methane, trans-1,4diamino-cyclohexane, and water molecules. Meanwhile, the high stability of CPOS-1 makes it a good candidate for proton conduction. Furthermore, it is important that CPOS-1 has a definite structure to allow clear analysis of the relationship between its proton conductivity and structure. However, the small pore volume will limit its capture of more protons.

Introducing an additional source of protons to its channels will greatly improve the proton conduction. Herein, we introduce nonvolatile acids [H2SO4(3.05 mol/L) and H3PO4(3.16 mol/L)] into crystalline porous organic salts(CPOS-1) to improve the proton conduction of CPOS-1.

2

Materials and Methods

2.1 Materials Tetrakis(4-sulfophenyl)methane was synthesized according to the ref.[22], and trans-1,4-diaminocyclohexane was purchased from TCI chemicals without further purification.