Highly Crystalline Mesoporous Phosphotungstic Acid: A High‐Performance Electrode Material for Energy‐Storage Applications

Abstract

Heteropoly acids (HPAs) are unique materials with interesting properties, including high acidity and proton conductivity. However, their low specific surface area and high solubility in polar solvents make them unattractive for catalytic or energy applications. This obstacle can be overcome by creating nanoporosity within the HPA. We synthesized mesoporous phosphotungstic acid (mPTA) with a spherical morphology through the self‐assembly of phosphotungstic acid (PTA) with a polymeric surfactant as stabilized by KCl and hydrothermal treatment. The mPTA nanostructures had a surface area of 93 m2 g−1 and a pore size of 4 nm. Their high thermal stability (ca. 450 °C) and lack of solubility in ethylene carbonate/diethyl carbonate (EC/DEC) electrolyte are beneficial for lithium‐ion batteries (LIBs). Optimized mPTA showed a reversible capacity of 872 mAh g−1 at 0.1 A g−1 even after 100 cycles for LIBs, as attributed to a super‐reduced state of HPA and the storage of Li ions within the mesochannels of mPTA.

Polyvinyl Alcohol Incorporated with Mesoporous Phosphotungstic Acid for Direct Methanol Fuel Cell Application

“…Moreover, the compactness and the distribution of mPTA-Si in the PVA matrix increases and more uniform (white dots are the mPTA-Si particles) with the increases of loading content (Figure 1b-e) It is suggested that the structural order of mPTA in PEM matrix was improved with the increases amount of mPTA [11], owing to the higher particles number (red circle) of fillers. In addition, the surface of the membranes also was found in smooth and no aggregation formed in the structure.…”

“…PTA is primarily used as a homogeneous catalyst for acid and oxidation, due to its high acidity and good oxidizing ability. Because the high oxidation level of 6 tungsten in PTA, reducing W 6+ to W 3+ in PTA may produce high energy and power densities for energy cells [11]. In addition, PTA also have been used in fuel cell applications to improve proton conductivity.…”

Polyoxometalates (POMs) with Ion/Electron‐Sponge Properties and Abundant Active Sites as Emerging Electrode Materials for Secondary Batteries: A Review

“…Ilbeygi et al. applied K 3 PW 12 O 40 to the anode material of LIBs and investigated its lithiation mechanism by analyzing the in‐situ X‐ray absorption spectroscopic during cycling test [19] . With the increase of cycling time, the anions of the K 3 PW 12 O 40 , [PW 6+ 12 O 40 ] 3− , are gradually reduced to a completely stabilized structure, [PW 4+ 12 O 40 ] 27− , and the valence state of W hardly ever changes after the 10 th cycle, indicating that the non‐Faradaic Li + storage contributes most of the capacity of K 3 PW 12 O 40 .…”