Synthesis and conductive performance of indium-substituted ternary heteropoly acids with Keggin structures

Abstract

Two new high-proton conductors, indium-substituted ternary heteropoly acids with Keggin structures, H4[In(H2O)PW11O39]·11H2O and H5[In(H2O)SiW11O39]·8H2O, have been synthesized and characterized using elemental analysis, IR, UV, XRD and TG-DTA. Their proton conductivities were measured using electrochemical impedance spectroscopy (EIS), and the results indicate that H4[In(H2O)PW11O39]·11H2O and H5[In(H2O)SiW11O39]·8H2O are solid high-proton conductors with a conductivity of 2.60 × 10(-4) S cm(-1) and 5.25 × 10(-4) S cm(-1), respectively, at 18 °C and 80% relative humidity (RH). Their activation energies are 33.40 kJ mol(-1) and 28.52 kJ mol(-1), which suggests that the mechanism of proton conduction is the vehicle mechanism. In the range of the measured temperatures, the conductivity of both heteropoly acids increases with higher temperatures.

Ultralow‐Loading and High‐Performing Ionic Liquid‐Immobilizing Rhodium Single‐Atom Catalysts for Hydroformylation

“…Then, the POM catalysts were subjected to UV‐vis characterization. As shown in Figure S3a and b, all samples showed UV‐vis absorption peaks at 200 nm, which belonged to O d →W (O d is the terminal oxygen) charge‐transfer band (CT) and was not affected by the cation and Rh‐substituted POMs [32] . In addition, K‐SiW and K‐PW showed absorption bands at 243 and 246 nm respectively, which belonged to O b /O c →W(O b is bridged between corner‐shared WO 6 octahedra and O c is bridged between edge‐shared WO 6 octahedra) transition and was the characteristic absorption peak of Keggin‐type POMs [33] .…”

“…As shown in Figure S3a and b, all samples showed UVvis absorption peaks at 200 nm, which belonged to O d !W (O d is the terminal oxygen) charge-transfer band (CT) and was not affected by the cation and Rh-substituted POMs. [32] In addition, K-SiW and K-PW showed absorption bands at 243 and 246 nm respectively, which belonged to O b /O c !W(O b is bridged between corner-shared WO 6 octahedra and O c is bridged between edge-shared WO 6 octahedra) transition and was the characteristic absorption peak of Keggin-type POMs. [33] The characteristic absorption peaks of K-SiWRh and K-PWRh from O b /O c !W transition red-shifted to 256 and 253 nmdue to mono-metal(Rh) substituted Keggin-type structure, respectively.…”

Proton Conductance of a Superior Water-Stable Metal–Organic Framework and Its Composite Membrane with Poly(vinylidene fluoride)

“…4,5 In this context, a number of efforts have been dedicated to exploring alternative types of PEMs, e.g., modified PFSA membranes, acid−base polymer membranes, and inorganic−organic composite membranes. 6−8 Nevertheless, the challenge still remains to develop new types of PEMs that meet the following requirements simultaneously: high proton conductivity with a value of 1.0 × 10 −4 S•cm −1 or above, 9 excellent thermal and chemical stability together with good mechanical performance, 10,11 and low-cost and facile manufacturing processes. 12 Metal−organic frameworks (MOFs) or porous coordination polymers are a class of new crystalline porous materials, emerging as the most promising candidates for next-generation proton-conducting materials because of the advantages of tremendous structural flexibility, large pore volume, and poresize tenability.…”

“…Perfluorosulfonic acid (PFSA) polymer membranes are the most commonly and widely used types of PEMs, and the Nafion membrane is a typical example. The Nafion membrane shows high proton conductivity (10 –1 –10 –2 S·cm –1 ) at moderate temperature (60–80 °C) and high relative humidity (98% RH) but high-cost and hazardous manufacturing processes and low thermal stability. , In this context, a number of efforts have been dedicated to exploring alternative types of PEMs, e.g., modified PFSA membranes, acid–base polymer membranes, and inorganic–organic composite membranes. − Nevertheless, the challenge still remains to develop new types of PEMs that meet the following requirements simultaneously: high proton conductivity with a value of 1.0 × 10 –4 S·cm –1 or above, excellent thermal and chemical stability together with good mechanical performance, , and low-cost and facile manufacturing processes …”

Facile fabrication of thermal-control ionic liquid compound based on undecatungstophosphoindic polyoxometalate with fast ionic conductivity

“…Synthesis of the POM-IL H 4 [In(H 2 O)PW 11 O 39 ] was synthesized using a procedure described in a previous report. 22 A solution of In(NO 3 ) 3 was dropped into a solution of Na 7 PW 11 O 39 at pH = 4.8, with the ratio of the substrates controlled at 1 : 1. A potassium salt was collected as a white powder after adding solid KCl into the solution.…”