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Because of the environmental benignity, abundance, and promising electrochemical properties of Ti-containing materials in batteries, these materials have been attracting the attention of the academic community. Herein, we report on KTiPO4F as a novel Ti-containing polyanionic negative electrode (anode) material with a robust framework structure, which is obtained via a facile hydrothermal synthesis route. A comprehensive analysis of the chemical composition, particle morphology, and electronic and crystal structure of KTiPO4F is performed using X-ray powder diffraction, electron microscopy, and spectroscopy methods. When tested against metallic K with a 1 M KPF6 electrolyte, the carbon-coated KTiPO4F reveals remarkable K-ion storage properties, delivering around 130 mA h g−1 at 130 mA g−1 with symmetric charge/discharge (1C rate) in the 0.001–3.0 V vs. K/K+ potential range with 97% capacity retention after 1000 cycles. This polyanion anode operates at an average potential of only 0.8 V vs. K/K+via a solid-solution-like de/insertion mechanism showing a cell volume change of 8.5% – the lowest value among modern benchmark electrode materials for potassium-ion batteries. A full symmetric K-ion KTiPO4F‖KTiPO4F cell is for the first time assembled and tested. This work complements the available range of anode materials for K-ion batteries with a new polyanionic representative thus extending the development frontiers. [ABSTRACT FROM AUTHOR]

Innovative models of teaching through research have broken the long-held paradigm that core chemistry competencies must be taught with predictable, scripted experiments. We describe here five fundamentally different, course-based undergraduate research experiences that integrate faculty research projects, accomplish ACS accreditation objectives, provide the benefits of an early research experience to students, and have resulted in publishable findings. The model detailed is the Freshman Research Initiative (FRI) at The University of Texas at Austin. While there are currently 30+ active FRI research groups, or "streams", we focus this report on five different chemistry streams in these four areas (organic, inorganic, analytical, and biochemistry) to demonstrate how general chemistry laboratory skills are taught in the context of these varied research disciplines. To illustrate the flexibility of the FRI model for teaching first-year chemistry, we show how each stream teaches students three different skills within the context of their research: making (synthesis), measuring (UV-vis spectroscopy), and characterization. As a unifying example, all five chemistry streams describe using UV-vis spectroscopy to characterize new synthetic molecules, complexes, and compounds, followed by extensive quantitative collection, processing, and analysis of experimental data sets. The FRI model allows full integration of training in mandatory and accredited general chemistry skill sets with open-ended research experiences with unexpected outcomes in undergraduate science curricula. In turn, this model enables undergraduates to be productive contributors to new knowledge and scientific discovery at the earliest levels of the undergraduate experience.

Hard carbon (HC) is considered as a negative electrode material for potassium-ion batteries, but it suffers from significant irreversible capacity loss at the first discharge cycle. Here, we investigated the possible reasons of this capacity loss with a combination of in situ AFM and various ex situ TEM techniques (high resolution TEM and high angle annular dark field scanning TEM imaging, and STEM-EELS and STEM-EDX spectroscopic mapping) targeting the electrode/electrolyte interphase formation process in the carbonate-based electrolyte with and without vinylene carbonate (VC) as an additive. The studied HC consists of curved graphitic layers arranged into short packets and round cages, the latter acting as traps for K+ ions causing low Coulombic efficiency between cycling. Our comparative study of solid electrolyte interphase (SEI) formation in the carbonate-based electrolyte with and without the VC additive revealed that in the pristine electrolyte, the SEI consists mostly of inorganic components, whereas adding VC introduces a polymeric organic component to the SEI, increasing its elasticity and stability against fracturing upon HC expansion/contraction during electrochemical cycling. Additionally, significant K+ loss occurs due to Na+ for K+ exchange in Na-carboxymethyl cellulose used as a binder. These findings reflect the cumulative impact of the internal HC structure, SEI properties, and binder nature into the electrochemical functional properties of the HC-based anodes for K-ion batteries. [ABSTRACT FROM AUTHOR]

Carbon soot has been known since antiquity, but has recently been finding new uses as a robust, inexpensive nanomaterial. This paper describes the superhydrophobic properties of carbon soot films prepared by combustion of candle wax or propane gas and introduces some of the optical absorption and fluorescence properties of carbon soot particles. Multiple demonstrations, appropriate for a variety of educational backgrounds, are presented. (Contains 6 figures.)