@article{ding_spencer_holzapfel_chagnot_augustyn_2025, title={Interlayer pillaring influences the octahedral tilting and electrochemical capacity of tungsten oxides}, ISSN={["2050-7496"]}, DOI={10.1039/d4ta08647c}, abstractNote={Pillaring tungsten oxides with alkylammonium cations increases the interlayer spacing but decreases the band gap, leading to low electrochemical capacity.}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Ding, Ran and Spencer, Michael A. and Holzapfel, Noah P. and Chagnot, Matthew and Augustyn, Veronica}, year={2025}, month={Feb} }
 @article{chagnot_abello_wang_dawlaty_rodriguez-lopez_zhang_augustyn_2024, title={Influence of Finite Diffusion on Cation Insertion-Coupled Electron Transfer Kinetics in Thin Film Electrodes}, volume={171}, ISSN={["1945-7111"]}, DOI={10.1149/1945-7111/ad1d98}, abstractNote={Materials that undergo ion-insertion coupled electron transfer are important for energy storage, energy conversion, and optoelectronics applications. Cyclic voltammetry is a powerful technique to understand electrochemical kinetics. However, the interpretation of the kinetic behavior of ion insertion electrodes with analytical solutions developed for ion blocking electrodes has led to confusion about their rate-limiting behavior. The purpose of this manuscript is to demonstrate that the cyclic voltammetry response of thin film electrode materials undergoing solid-solution ion insertion without significant Ohmic polarization can be explained by well-established models for finite diffusion. To do this, we utilize an experimental and simulation approach to understand the kinetics of Li + insertion-coupled electron transfer into a thin film material (Nb 2 O 5 ). We demonstrate general trends for the peak current vs scan rate behavior, with the latter parameter elevated to an exponent between limiting values of 1 and 0.5, depending on the solid-state diffusion characteristics of the film (diffusion coefficient, film thickness) and the experiment timescale (scan rate). We also show that values < 0.5 are possible depending on the cathodic potential limit. Our results will be useful to fundamentally understand and guide the selection and design of intercalation materials for multiple applications.}, number={1}, journal={JOURNAL OF THE ELECTROCHEMICAL SOCIETY}, author={Chagnot, Matthew and Abello, Sofia and Wang, Ruocun and Dawlaty, Jahan and Rodriguez-Lopez, Joaquin and Zhang, Chao and Augustyn, Veronica}, year={2024}, month={Jan} }
 @article{holzapfel_chagnot_abdar_paudel_crumlin_mckone_augustyn_2024, title={Solution-Phase Synthesis of Platinum-Decorated Hydrogen Tungsten Bronzes for Hydrogen Atom Transfer from Oxides to Molecules}, ISSN={["1520-5002"]}, DOI={10.1021/acs.chemmater.4c02814}, abstractNote={Hydrogen bronzes can be used as hydrogen donors for the broad class of reactions involving proton-coupled electron transfer (PCET). Here, we describe a method to prepare platinum-decorated hydrogen tungsten bronzes, Pt@HxWO3·nH2O with n = 0, 1, and 2, by reacting the pristine oxides at modest temperatures with a mild reducing agent, H3PO2, and H2PtCl6 in an aqueous solution. We explored the tunability and kinetics of this reaction and compared it with that of archetypal gas–solid hydrogen spillover. We demonstrate that the identity of the noble metal affects the extent of bronze reduction. This suggests that the mechanism proceeds via the adsorption of a hydrogen-atom species on the noble metal. Finally, we explored the ability of the Pt-decorated hydrogen tungsten bronzes to hydrogenate a model H+/e– acceptor, 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO). The bronze phases return to their fully oxidized states along with the subsequent reduction of TEMPO to TEMPOH. Overall, this work demonstrates a solution-phase method to obtain hydrogen bronzes, which can then be used to perform hydrogen transfer reactions, providing a pathway for the use of extended transition metal oxides as stoichiometric reagents for broad classes of hydrogenation reactions.}, journal={CHEMISTRY OF MATERIALS}, author={Holzapfel, Noah P. and Chagnot, Matthew and Abdar, Payman Sharifi and Paudel, Jay R. and Crumlin, Ethan J. and Mckone, James R. and Augustyn, Veronica}, year={2024}, month={Nov} }
 @article{fortunato_zydlewski_lei_holzapfel_chagnot_mitchell_lu_jiang_milliron_augustyn_2023, title={Dual-Band Electrochromism in Hydrous Tungsten Oxide}, ISSN={["2330-4022"]}, DOI={10.1021/acsphotonics.3c00921}, abstractNote={The independent modulation of visible and near-infrared light by a single material, termed dual-band electrochromism, is highly desirable for smart windows to enhance the energy efficiency of buildings. Tungsten oxides are commercially important electrochromic materials, exhibiting reversible visible and near-infrared absorption when electrochemically reduced in an electrolyte containing small cations or protons. The presence of structural water in tungsten oxides has been associated with faster electrochromic switching speeds. Here, we find that WO3·H2O, a crystalline hydrate, exhibits dual-band electrochromism unlike the anhydrous WO3. This provides a heretofore unexplored route to tune the electrochromic response of tungsten oxides. Absorption of near-infrared light is achieved at low Li+/e– injection, followed by the absorption of visible light at higher Li+/e– injection as a result of an electrochemically induced phase transition. We propose that the dual-band modulation is possible due to the more open structure of WO3·H2O as compared to WO3. This facilitates a more extended solid-solution Li+ insertion regime that benefits the modulation of near-infrared radiation via plasmon absorption. Higher degrees of Li+/e– insertion lead to polaronic absorption associated with localized charge storage. These results inform how structural factors influence the electrochemically induced spectral response of transition-metal oxides and the important role of structural water beyond optical switching speed.}, journal={ACS PHOTONICS}, author={Fortunato, Jenelle and Zydlewski, Benjamin Z. and Lei, Ming and Holzapfel, Noah P. and Chagnot, Matthew and Mitchell, James B. and Lu, Hsin-Che and Jiang, De-en and Milliron, Delia J. and Augustyn, Veronica}, year={2023}, month={Sep} }
 @misc{mitchell_chagnot_augustyn_2023, title={Hydrous Transition Metal Oxides for Electrochemical Energy and Environmental Applications}, volume={53}, ISSN={["1545-4118"]}, DOI={10.1146/annurev-matsci-080819-1249550}, journal={ANNUAL REVIEW OF MATERIALS RESEARCH}, author={Mitchell, James B. and Chagnot, Matthew and Augustyn, Veronica}, year={2023}, pages={1–23} }