Surface-oxygen induced electrochemical self-assembly of mesoporous conducting polymers for electrocatalysis

Porous polymers have immense potential in catalysis, energy conversion and storage, separation sciences and life sciences due to their high surface area and high diffusion flux. Developing porous polymers with micro and mesoscale porosity with long-range order is challenging and involves multistep templated approaches. Here we demonstrate a simple surface-oxygen induced electropolymerization route to directly obtain self-assembled porous polymers of polyparaphenylene (PPP) and PPP based copolymers in ionic liquids. By combining experimental and theoretical studies, we show that surface oxygen on Cu changes the orientation and assembly of benzene which then results in a change in electropolymerization mechanism leading to a selfassembled porous structure with porosity between 2 and 5 μm. Furthermore, with controlled experimental parameters, bicontinuous conducting polymers with porosity of >10 μm are obtained. The porous conducting polymers show absorption of light in the visible range which was also used as an efficient electrode for investigation of the photo/electrochemical oxygen evolution reaction

Electrodeposition of zinc nanoplates from an ionic liquid composed of 1-butylpyrrolidine and ZnCl2: electrochemical, in situ AFM and spectroscopic studies

The mixtures of 1-butylpyrrolidine and ZnCl2 result in the formation of an ionic liquid, which can be used as an electrolyte for zinc electrodeposition. The feasibility of electrodepositing Zn from these electrolytes was investigated at RT and at 60 °C. The synthesized mixtures are rather viscous. Toluene was added to the mixtures to decrease the viscosity of the ILs. Vibrational spectroscopy was employed for the characterization of the liquids. The electrochemical behaviour of the liquids was evaluated by cyclic voltammetry. The electrode/electrolyte interface of this IL was probed by Atomic Force Microscopy (AFM). The suitable range for the electrodeposition of Zn was found to be ≥28.6 mol% of ZnCl2. Zn deposition occurs mainly from the cationic species of [ZnClxLy]+ (where x = 1, y = 1–2, and L = 1-butylpyrrolidine) in these electrolytes. This is in contrary to the well investigated chlorozincate ionic liquids where the deposition of Zn occurs mainly from anionic chlorozincates. Nanoplates of Zn were obtained from these mixtures of 1-butylpyrrolidine and ZnCl2

In situ atomic force microscopic studies of the interfacial multilayer nanostructure of LiTFSI–[Py₁, ₄]TFSI on Au(111): influence of Li+ ion concentration on the Au(111)/IL interface

In this paper, we present results on the nanoscale interactions of LiTFSI–[Py2081₁_, ₄]TFSI with Au(111) using cyclic voltammetry and atomic force microscopy (AFM). Raman spectroscopy was used to understand the Li⁺ ion coordination with the TFSI– ion and showed that with increase in LiTFSI concentration in[Py₁_, ₄]TFSI, the Li+ ion solvation structure significantly changes. Correspondingly, the force–distance profile in AFM revealed that at lower concentrations of LiTFSI (0.1 M) a multilayered structure is obtained. On increasing the concentration of LiTFSI (0.5 and 1 M), a significant decrease in the number of interfacial layers was observed. With change in the potential, the interfacial layers were found to vary with an increase in the force required to rupture the layers. The present study clearly shows that Li⁺ ions vary the ionic liquid/Au(111) interface and could provide insight into the interfacial processes in ionic liquid based lithium batteries

In situ scanning tunneling microscopy (STM), atomic force microscopy (AFM) and quartz crystal microbalance (EQCM) studies of the electrochemical deposition of tantalum in two different ionic liquids with the 1-butyl-1-methylpyrrolidinium cation

The electrochemical reduction of 0.1 M TaF₅ in two hydrophobic ionic liquids (1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate ([Py_1,4]FAP) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide ([Py_1,4]TFSA) is probed using three <i>in situ</i> techniques: scanning tunneling microscopy (STM), atomic force microscopy (AFM), and electrochemical quartz crystal microbalance (EQCM). These techniques reveal that under similar conditions TaF₅is more easily reduced in the liquids with [TFSA]⁻ than [FAP]⁻anions. Increasing the temperature reduced the viscosity and density of the ionic liquids which facilitates TaF₅ electroreduction, in particular, in [Py_1,4]TFSA. A herringbone reconstruction of the Au electrode was observed by STM for both ionic liquids with and without TaF₅. Ta deposition was proved by STM and EQCM in [Py_1,4]TFSA. Cracked layers, with ionic liquid trapped inside, were obtained by direct plating from the [TFSA]− ionic liquid. No Ta containing deposits could be obtained in the liquid with the [FAP]− anion

[Py_1,4]FSI-NaFSI-Based Ionic Liquid Electrolyte for Sodium Batteries: Na⁺ Solvation and Interfacial Nanostructure on Au(111)

The NaFSI-[Py_1,4]­FSI/Au­(111) interface was investigated using cyclic voltammetry (CV) and in situ atomic force microscopy (AFM). Raman spectroscopy was used to evaluate the Na⁺ solvation in [Py_1,4]­FSI. It was found that Na coordinates with three FSI^– forming [Na­(FSI)₃]^2–. In situ AFM revealed that the interaction of [Py_1,4]­FSI with Au(111) is much stronger compared with other ionic liquids measured using the same technique. On applying a potential, a force of ∼50 nN is required to penetrate through the innermost layer. On addition of low concentration of NaFSI (0.05 M), an insignificant change in the innermost solvation layer was observed, whereas on addition of 0.25 and 0.5 M NaFSI, a significant change in the interfacial structure was noted. The present study clearly shows that Na⁺ ions vary the ionic liquid/Au(111) interface and could provide insight into the interfacial processes in ionic-liquid-based sodium batteries

Nanostructure of the H-terminated p-Si(111)/ionic liquid interface and the effect of added lithium salt

Ionic liquids are potential electrolytes for safe lithium-ion batteries (LIB). Recent research has probed the use of silicon as an anode material for LIB with various electrolytes. However, the nanostructure of the ionic liquid/Si interface is unknown. The present communication probes the hydrogen terminated p-Si(111) interface using atomic force microscopy (AFM) in 1-ethyl-3-methylimidazolium bis(trifluoromethlysulfonyl)amide ([EMIm]TFSA) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethlysulfonyl)amide ([Py1,4]TFSA). AFM measurements reveal that the imidazolium cation adsorbs at the H-Si(111)/[EMIm]TFSA interface leading to an ordered clustered facet structure of ∼3.8 nm in size. In comparison, the Si(111)/[Py1,4]TFSA interface appeared the same as the native surface in argon. For both pure ILs, repulsive forces were measured as the tip approached the surface. On addition of LiTFSA attractive forces were measured, revealing marked changes in the interfacial structure

In Situ Atomic Force Microscopic Studies of the Interfacial Multilayer Nanostructure of LiTFSI–[Py_{1, 4}]TFSI on Au(111): Influence of Li⁺ Ion Concentration on the Au(111)/IL Interface

In this paper, we present results on the nanoscale interactions of LiTFSI–[Py_1, 4]­TFSI with Au(111) using cyclic voltammetry and atomic force microscopy (AFM). Raman spectroscopy was used to understand the Li⁺ ion coordination with the TFSI^– ion and showed that with increase in LiTFSI concentration in [Py_1, 4]­TFSI, the Li⁺ ion solvation structure significantly changes. Correspondingly, the force–distance profile in AFM revealed that at lower concentrations of LiTFSI (0.1 M) a multilayered structure is obtained. On increasing the concentration of LiTFSI (0.5 and 1 M), a significant decrease in the number of interfacial layers was observed. With change in the potential, the interfacial layers were found to vary with an increase in the force required to rupture the layers. The present study clearly shows that Li⁺ ions vary the ionic liquid/Au(111) interface and could provide insight into the interfacial processes in ionic liquid based lithium batteries