@article{saeed_fortunato_ganeshan_duin_augustyn_2021, title={Decoupling Proton and Cation Contributions to Capacitive Charge Storage in Birnessite in Aqueous Electrolytes}, volume={8}, ISSN={["2196-0216"]}, DOI={10.1002/celc.202100992}, abstractNote={Nanostructured birnessite is of interest as an electrode material for aqueous high power electrochemical energy storage as well as desalination devices. In neutral pH aqueous electrolytes, birnessite exhibits a capacitive response attributed to the adsorption of cations and protons at the outer surface and within the hydrated interlayer. Here, we utilize the understanding of proton-coupled electron transfer (PCET) in buffered electrolytes to decouple the role of protons and cations in the capacitive charge storage mechanism of birnessite at neutral pH. We find that without buffer, birnessite exhibits primarily potential-independent (capacitive) behavior with excellent cycling stability. Upon the addition of buffer, the capacity initially increases and the cyclic voltammograms become more potential-dependent, features attributed to the presence of PCET with the birnessite. However, long-term cycling in the buffered electrolyte leads to significant capacity fade and dissolution, which is corroborated through ex situ characterization. ReaxFF atomistic scale simulations support the observations that proton adsorption leads to birnessite degradation and that capacitive charge storage in birnessite is primarily attributed to cation adsorption at the outer surface and within the interlayer.}, number={22}, journal={CHEMELECTROCHEM}, author={Saeed, Saeed and Fortunato, Jenelle and Ganeshan, Karthik and Duin, Adri C. T. and Augustyn, Veronica}, year={2021}, month={Nov}, pages={4371–4379} }
 @article{boyd_ganeshan_tsai_wu_saeed_jiang_balke_duin_augustyn_2021, title={Effects of interlayer confinement and hydration on capacitive charge storage in birnessite}, ISSN={["1476-4660"]}, url={https://doi.org/10.1038/s41563-021-01066-4}, DOI={10.1038/s41563-021-01066-4}, abstractNote={Nanostructured birnessite exhibits high specific capacitance and nearly ideal capacitive behaviour in aqueous electrolytes, rendering it an important electrode material for low-cost, high-power energy storage devices. The mechanism of electrochemical capacitance in birnessite has been described as both Faradaic (involving redox) and non-Faradaic (involving only electrostatic interactions). To clarify the capacitive mechanism, we characterized birnessite’s response to applied potential using ex situ X-ray diffraction, electrochemical quartz crystal microbalance, in situ Raman spectroscopy and operando atomic force microscope dilatometry to provide a holistic understanding of its structural, gravimetric and mechanical responses. These observations are supported by atomic-scale simulations using density functional theory for the cation-intercalated structure of birnessite, ReaxFF reactive force field-based molecular dynamics and ReaxFF-based grand canonical Monte Carlo simulations on the dynamics at the birnessite–water–electrolyte interface. We show that capacitive charge storage in birnessite is governed by interlayer cation intercalation. We conclude that the intercalation appears capacitive due to the presence of nanoconfined interlayer structural water, which mediates the interaction between the intercalated cation and the birnessite host and leads to minimal structural changes.}, journal={NATURE MATERIALS}, author={Boyd, Shelby and Ganeshan, Karthik and Tsai, Wan-Yu and Wu, Tao and Saeed, Saeed and Jiang, De-en and Balke, Nina and Duin, Adri C. T. and Augustyn, Veronica}, year={2021}, month={Aug} }
 @article{saeed_boyd_tsai_wang_balke_augustyn_2021, title={Understanding electrochemical cation insertion into prussian blue from electrode deformation and mass changes}, volume={57}, ISSN={["1364-548X"]}, url={https://doi.org/10.1039/D1CC01681D}, DOI={10.1039/d1cc01681d}, abstractNote={Alkali ion insertion into Prussian blue from aqueous electrolytes is characterized with <italic>operando</italic> AFM and EQCM, showing coupling of current with deformation and mass change rates.}, number={55}, journal={CHEMICAL COMMUNICATIONS}, publisher={Royal Society of Chemistry (RSC)}, author={Saeed, Saeed and Boyd, Shelby and Tsai, Wan-Yu and Wang, Ruocun and Balke, Nina and Augustyn, Veronica}, year={2021}, month={Jul}, pages={6744–6747} }