Formulating Zwitterionic, Responsive Polymers for Designing Smart Soils.

The design of new remediation strategies and materials for treating saline-alkaline soils is of fundamental and practical importantance for many applications. Conventional soil remediation strategies mainly focus on the development of fertilizers or additives for water, nutrient, and heavy metal managements in soils, but they often overlook a soil sensing function for early detection of salinization/alkalization levels toward optimal and timely soil remediation. Here, new smart soils, structurally consisting of the upper signal soil and the bottom hygroscopic bed and chemically including zwitterionic, thermo-responsive poly(NIPAM-co-VPES) and poly(NIPAM-co-SBAA) aerogels in each soil layer are formulated.

Non-thermal plasma-assisted rapid hydrogenolysis of polystyrene to high yield ethylene.

The evergrowing plastic production and the caused concerns of plastic waste accumulation have stimulated the need for waste plastic chemical recycling/valorization. Current methods suffer from harsh reaction conditions and long reaction time. Herein we demonstrate a non-thermal plasma-assisted method for rapid hydrogenolysis of polystyrene (PS) at ambient temperature and atmospheric pressure, generating high yield (>40 wt%) of C-C hydrocarbons and ethylene being the dominant gas product (Selectivity of ethylene, S > 70%) within ~10 min.

Improved Polydopamine Deposition in Amine-Functionalized Silica Aerogels for Enhanced UV Absorption.

Silica aerogels are interesting porous materials with extremely low density and high surface area, making them advantageous for a number of aerospace and catalysis applications. Here, we report the preparation of polydopamine (PDA)-functionalized silica aerogels using an coating method, wherein the dopamine monomer was allowed to diffuse through the underlying structure of the gels in the absence of any external base and polymerize on the surface of the gel. The use of a siloxane precursor with an amine functionality decorates the silica backbone, allowing for a superior PDA coating, as evident in the darker color of PDA-coated amine-functionalized silica gels than PDA-coated silica-only gels and the X-ray photoelectron spectroscopy results.

Accurate Determination of the Quantity and Spatial Distribution of Counterions around a Spherical Macroion.

The accurate distribution of countercations (Rb and Sr ) around a rigid, spherical, 2.9-nm size polyoxometalate cluster, {Mo } , is determined by anomalous small-angle X-ray scattering. Both Rb and Sr ions lead to shorter diffuse lengths for {Mo } than prediction.

Mechanism of UVA Degradation of Synthetic Eumelanin.

Eumelanin is a ubiquitous natural pigment that has a broad absorption across ultraviolet (UV, 100-400 nm) and visible wavelengths (400-700 nm) and can protect against radiation. Synthetic eumelanin with properties similar to natural eumelanin has been made using dopamine or dihydroxyindole. Here, we use solid-state nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy to elucidate the chemical structure of synthetic eumelanins (made from dopamine and l-3,4-dihydroxyphenylalanine precursors) and investigate how their structures change after intensive UVA (315-400 nm) exposure.

In situ infrared study of photo-generated electrons and adsorbed species on nitrogen-doped TiO in dye-sensitized solar cells.

Charge transfer between adsorbed dyes and the TiO2 surface plays a key role in controlling the efficiency of dye-sensitized solar cells (DSSCs). The lack of understanding of charge transfer steps has hindered further development of DSSCs and many solar energy conversion devices/processes. In this study, we used in situ infrared spectroscopy to investigate electron transfer and photo-electric energy conversion processes at the interface, i.

A Spontaneous Structural Transition of {U Pp } Clusters Triggered by Alkali Counterion Replacement in Dilute Solution.

A transition between two isomeric clusters involving the change of the main skeleton structure of a well-defined, rigid molecular cluster [(UO ) (O ) (P O ) ] , {U Pp }, is achieved by simply introducing proper alkali cations into its dilute aqueous solution. While the unique structural transition can be triggered by introducing any of the Na /K /Rb /Cs alkali ions, the two isomers, Li/Na-{U Pp } and Na/K-{U Pp }, as typical macroions, can accurately choose among different alkali counter-cations based on their hydrated sizes, and the ion selectivity process clearly showed endothermic features. The preferred K and Rb ions have suitable sizes to be incorporated into the proper windows on {U Pp } nanocapsules, as supported by the transition points in both ITC studies and IR measurements.

Enhanced Thermoelectric Properties of Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) by Binary Secondary Dopants.

Unlabelled: To simultaneously increase the electrical conductivity and Seebeck coefficient of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (

Pedot: PSS) was a challenge for realizing efficient organic thermoelectrics. In this study, for the first time, we report both increased electrical conductivities and Seebeck coefficients, hence, enhanced thermoelectric properties of

Pedot: PSS thin films by doped with binary secondary dopants, dimethyl sulfoxide (DMSO) and poly(ethylene oxide) (PEO). Without modifying film morphology, the molar ratios of PEDOT to PSS are tuned by PEO, resulting in increased proportions of PEDOT in the bipolaron states.

In situ ATR and DRIFTS studies of the nature of adsorbed CO₂ on tetraethylenepentamine films.

CO2 adsorption/desorption onto/from tetraethylenepentamine (TEPA) films of 4, 10, and 20 μm thicknesses were studied by in situ attenuated total reflectance (ATR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) techniques under transient conditions. Molar absorption coefficients for adsorbed CO2 were used to determine the CO2 capture capacities and amine efficiencies (CO2/N) of the films in the DRIFTS system. Adsorption of CO2 onto surface and bulk NH2 groups of the 4 μm film produced weakly adsorbed CO2, which can be desorbed at 50 °C by reducing the CO2 partial pressure.

In situ infrared study of the effect of amine density on the nature of adsorbed CO2 on amine-functionalized solid sorbents.

In situ Fourier transform infrared spectroscopy was used to determine the nature of adsorbed CO2 on class I (amine-impregnated) and class II (amine-grafted) sorbents with different amine densities. Adsorbed CO2 on amine sorbents exists in the form of carbamate-ammonium ion pairs, carbamate-ammonium zwitterions, and carbamic acid. The adsorbed CO2 on high-amine density sorbents showed that the formation of ammonium ions correlates with the suppression of CH stretching intensities.

In situ pulse diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) mass spectrometry study of the water-gas shift reaction on nickel(II) oxide-zinc(II) oxide catalysts.

The water-gas shift (WGS) reaction has been studied by pulsing carbon monoxide (CO) into a steady-state water (H2O)-Ar flow over nickel(II) oxide-zinc oxide (NiO-ZnO) catalysts using in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) coupled with a mass spectrometer method using the pulse technique (in situ pulse DRIFTS-MS) for different flow rates (gas hourly space velocity [GHSV] of 24,000-72,000 h(-1)) and reaction temperatures (250-350 °C). The results obtained from the in situ pulse DRIFTS-MS revealed that there are two types of water adsorption bands on the surface of the catalyst: (i) molecular adsorption (infrared [IR] bands in the 2500-3600 cm(-1) range and at 1640 cm(-1)), and (ii) dissociative adsorption at 3700 cm(-1), where carboxyl bands are formed at 1461 and 1368 cm(-1) and the gas-phase CO is adsorbed at 2187 and 2111 cm(-1) on the surface of the catalyst. After using a GHSV = 24,000 h(-1) H2O/Ar flow, we probed the existence of two active intermediates via the formation of two hydrogen production peaks.

Spectroscopic investigation into oxidative degradation of silica-supported amine sorbents for CO(2) capture.

Oxidative degradation characteristics of silica-supported amine sorbents with varying amounts of tetraethylenepentamine (TEPA) and polyethylene glycol (PEG; P(200) or P(600) represents PEG with molecular weights of 200 or 600) have been studied by IR and NMR spectroscopy. Thermal treatment of the sorbents and liquid TEPA at 100 °C for 12 h changed their color from white to yellow. The CO(2) capture capacity of the TEPA/SiO(2) sorbents (i.

In situ infrared study of the role of PEG in stabilizing silica-supported amines for CO(2) capture.

The CO(2) capture capacity, adsorption mechanism, and degradation characteristics of two sorbents, silica-supported tetraethylenepentamine (TEPA/SiO(2)) and polyethylene-glycol-modified TEPA/SiO(2) (PEG/TEPA/SiO(2)), are studied by diffuse reflectance infrared Fourier transform spectroscopy and mass spectrometry. The CO(2) capture capacities of TEPA/SiO(2) and PEG/TEPA/SiO(2) are determined to be 2087 and 1110 micromol CO(2) g(-1) sorbent, respectively. Both sorbents adsorb CO(2) as hydrogen-bonding species, NH(2)--O, and carbamate/carboxylate species.

Tracing the reaction steps involving oxygen and IR observable species in ethanol photocatalytic oxidation on TiO2.

The rate-determining step of ethanol photocatalytic oxidation was identified to be the adsorption of O(2) by an infrared (IR) spectroscopy coupled with mass spectrometry method. Dosing O(2) during reaction showed that adsorption of O(2) controls the accumulation of photogenerated electrons and the formation of acetate (CH(3)COO(-)(ad)), acyl species (CH(3)CO(ad)), acetaldehyde (CH(3)CHO(ad)), CO(2), and H(2)O. Accumulation of CH(3)COO(-)(ad) on the TiO(2) surface slowed down the conversion of ethanol to CO(2) and H(2)O.