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Improving electrolyte stability to suppress water electrolysis represents a basic principle for designing aqueous batteries. Herein, we investigate counterintuitive roles that water electrolysis plays in regulating intercalation chemistry. Using the Na

The diffusion layer created by transition metal (TM) dissolution is ubiquitous at the electrochemical solid-liquid interface and plays a key role in determining electrochemical performance. Tracking the spatiotemporal dynamics of the diffusion layer has remained an unresolved challenge. With spatially resolved synchrotron X-ray fluorescence microscopy and micro-X-ray absorption spectroscopy, we demonstrate the in situ visualization and chemical identification of the dynamic diffusion layer near the electrode surface under electrochemical operating conditions. Our method allows for direct mapping of the reactive electrochemical interface and provides insights into engineering the diffusion layer for improving electrochemical performance. National Science Foundation [CBET 1912885]; DOE Office of Science [DE-AC02-06CH11357] Published version The work was supported by the National Science Foundation under no. CBET 1912885. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract no. DE-AC02-06CH11357. We thank Dr. Cheng-Jun Sun for the W L3-edge hard X-ray absorption spectroscopy measurement of bulk WO3 electrode without electrolyte at the beamline 20-BM-B at the Advanced Photon Source, Argonne National Laboratory.

Achieving stable, low-cost electrocatalysts represents a daunting challenge towards practical water oxidation reactions. Here, we report that a degraded electrocatalyst can be revivified under catalytic operating conditions by manipulating reversible phase segregation. Under the oxygen evolution reaction conditions, Fe segregation develops in the Ni–Fe hydroxide host lattice, with the formation of FeOOH, resulting in an interface between the FeOOH and the host lattice. A dynamic metal dissolution–redeposition process accelerates the Fe segregation and formation of the FeOOH secondary phase, resulting in catalyst deactivation. Operando synchrotron spectroscopic and microscopic analyses suggest that the phase segregation is reversible between the water oxidation potential and the catalyst reduction potential. Therefore, we have developed an intermittent reduction methodology to revivify the catalytic activity under the operating conditions, enhancing catalyst durability. The present study highlights that tailoring phase segregation at the catalyst/electrolyte interface constitutes an important strategy for revivifying and stabilizing catalytic activity. Achieving long-term stability of water oxidation electrocatalysts remains a formidable challenge. Now, an in situ electrochemical reduction strategy to revivify mixed Ni–Fe hydroxide catalysts by reversible phase segregation is presented.

Understanding how various redox activities evolve and distribute in disordered rocksalt oxides (DRX) can advance insights into manipulating materials properties for achieving stable, high-energy batteries. Herein, the authors present how the reaction kinetics and spatial distribution of redox activities are governed by the particle size of DRX materials. The size-dependent electrochemical performance is attributed to the distinct cationic and anionic reaction kinetics at different sizes, which can be tailored to achieve optimal capacity and stability. Overall, the local charged domains in DRX particles display random heterogeneity caused by the isotropic delithiation pathways. Owing to the kinetic limitation, the micron-sized particles exhibit a holistic "core-shell" charge distribution, whereas sub-micron particles show more uniform redox reactions throughout the particles and ensembles. Sub-micron DRX particles exhibit increasing anionic redox activities yet inferior cycling stability. In summary, engineering particle size can effectively modulate how cationic and anionic redox activities evolve and distribute in DRX materials. Thomas F. and Kate Miller Jeffress Memorial Trust; Bank of America; Jeffress Trust Awards Program in Interdisciplinary Research; National Science Foundation [DMR-2045570]; U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-AC02-76SF00515]; DOE Office of Science [DE-AC02-06CH11357, DE-SC0012704]; Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant [841621]; Walter Ahlstrom Foundation Published version The work was supported by the Thomas F. and Kate Miller Jeffress Memorial Trust, Bank of America, Trustee and the Jeffress Trust Awards Program in Interdisciplinary Research, and the National Science Foundation (DMR-2045570). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Research conducted at Spallation Neutron Source in Oak Ridge National Laboratory (NOMAD) was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. S.S. has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 841621. S.S. acknowledges funding from the Walter Ahlstrom Foundation. Y.Z. and F. L. thank Dr. X. Wang for the fruitful discussion.

In the spinel oxide cathode family, LiNi0.5Mn1.5O4 (LNMO) shows a high operating voltage (approximate to 4.7 V vs Li/Li+) and excellent Li-ion mobility with stable 3D conducting channels. Ni/Mn cation disordered and ordered phases usually coexist in LNMO materials, and they have distinct structural and electrochemical properties, resulting in different battery performances for LNMO materials with different phase compositions. Identifying the correlation between phase compositions and electrochemical properties is of significance to the improvement of battery performance and understanding of degradation mechanisms. Herein, the disordered/ordered phase compositions in LNMO materials are tailored by post-annealing strategies and their impacts on electrochemical performance and degradation mechanisms from the surface to the bulk are systematically investigated. The ordered phase increases rapidly as Mn3+ is oxidized to Mn4+ through a post-annealing process. LNMO with an intermediate fraction of disordered and ordered phases gives rise to improved cycling stability. This article further reports that a high ordered phase fraction can preferentially protect Ni from dissolution during cycling. However, these results suggest that the transition metal dissolution and surface structural change of LNMO do not exhibit a direct correlation with cycling stability. These results indicate the capacity fading mainly correlates with the bulk structural distortion, leading to decreased Li-ion kinetics. Department of Chemistry startup funds; U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-AC02-76SF00515]; Applied Battery Research (ABR) for Transportation Program; U.S. DOE Office of Science, Office of Basic Energy Sciences [DE-AC05-00OR22725]; U.S. DOE Office of Science User Facility [DE-AC02-05CH11231]; Walter Ahlstrom Foundation; European Union's Horizon 2020 research and innovation programme under the Marie Skodowska-Curie grant [841621] Published version The work at Virginia Tech was supported by Department of Chemistry startup funds. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. The pristine LNMO powder was produced at the U.S. Department of Energy's (DOE) CAMP (Cell Analysis, Modeling and Prototyping) Facility, Argonne National Laboratory. The CAMP Facility is fully supported by the DOE Vehicle Technologies Program (VTP) within the core funding of the Applied Battery Research (ABR) for Transportation Program. This research used resources of the Advanced Photon Sources at Argonne National Laboratory, which is a U.S. DOE Office of Science User Facility under contract No. DE-AC02-06CH11357. The use of the Spallation Neutron Source at Oak Ridge National Laboratory was supported by the U.S. DOE Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC05-00OR22725. This research used resources of the Advanced Light Source at Lawrence Berkeley National Laboratory, which is a U.S. DOE Office of Science User Facility under contract No. DE-AC02-05CH11231. The authors thank Dr. Gi-Hyeok Lee and Dr. Wanli Yang for fruitful discussion and soft XAS experiments. S.S. acknowledges funding from the Walter Ahlstrom Foundation. S.S. received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skodowska-Curie grant agreement No 841621.

The surface of an electrocatalyst undergoes dynamic chemical and structural transformations under electrochemical operating conditions. There is a dynamic exchange of metal cations between the electrocatalyst and electrolyte. Understanding how iron in the electrolyte gets incorporated in the nickel hydroxide electrocatalyst is critical for pinpointing the roles of Fe during water oxidation. Here, we report that iron incorporation and oxygen evolution reaction (OER) are highly coupled, especially at high working potentials. The iron incorporation rate is much higher at OER potentials than that at the OER dormant state (low potentials). At OER potentials, iron incorporation favors electrochemically more reactive edge sites, as visualized by synchrotron X-ray fluorescence microscopy. Using X-ray absorption spectroscopy and density functional theory calculations, we show that Fe incorporation can suppress the oxidation of Ni and enhance the Ni reducibility, leading to improved OER catalytic activity. Our findings provide a holistic approach to understanding and tailoring Fe incorporation dynamics across the electrocatalyst-electrolyte interface, thus controlling catalytic processes.

Controlling the electrochemical interfacial processes that govern the durability of electrochromic devices represents a key challenge in developing sustainable and cost-effective smart windows. Here, we revisit the classical tungsten trioxide (WO3) materials as a platform to uncover the previously unknown interrelationship between phase transformation, morphological evolution, and nanoscale color heterogeneity in these materials. Through synchrotron/electron spectroscopic and imaging analyses, we report that the WO3–electrolyte interface is influenced by the tungsten dissolution and redeposition during the electrochemical cycling. The tungsten redeposition provokes the in situ crystal growth, which ultimately leads to the phase transformation from the semicrystalline WO3 to a nanoflake-shaped, proton-trapped tungsten trioxide dihydrate (HxWO3·2H2O). The multidimensional quantification of the electronic structure reveals that the tungsten reduction caused by the proton trapping is heterogeneous at the nanometric scale and is responsible for the nanoscale color heterogeneity. The interplay between phase transformation, morphological evolution, and nanoscale color heterogeneity results in degraded optical modulation, switching kinetics, coulombic efficiency, and bleached-state transparency. Our results highlight that the high interfacial reactivity near the electrode surface may be the underlying mechanism for undesired bulk structural changes of electrochromic materials, and calls for fundamental studies in probing and controlling the electrode–electrolyte interfacial processes in electrochromic devices.

The electrode-electrolyte interface governs the efficiency and life time of almost all electrochemical reactions. Essentially, this interface, as a geometrically confined environment, allows many interfacial reactions occurring and provides a versatile toolbox of tailoring electrode surface chemistry under operating conditions. Here, through synchrotron spectroscopic, microscopic, and imaging characterizations, using the electrochromic tungsten trioxide (WO3) in an acidic electrolyte as the research platform, we reveal that the performance degradation is related to electrode material morphology evolution, phase transformation, and charge heterogeneity. We experimentally demonstrate that WO3 dissolution and redeposition across the electrochemical interface trigger all these evolutions. The redeposition process provokes the in situ crystal growth, inducing the evolution from the semicrystalline WO3 to the single-crystalline, nanoflake-shaped, proton-trapped tungsten trioxide di-hydrate (H x WO3·2H2O). Importantly, as a ubiquitous phenomenon, transition metal dissolution will form the diffusion layer at the interface. We have established a novel experimental design to probe and understand how the dissolved transition metal species evolve in the diffusion layer. The thickness of the diffusion layer is up to tens of micrometers, and the local electronic structure of dissolved species varies with the distance from the electrode surface. Furthermore, this dynamic dissolution and redeposition feature can be manipulated to regulate the chemical composition and crystal structure of the electrode surface as well as the overall electrochemical performance. Foreign cations (e.g., Ti4+), either added as electrolyte additives or dissolved from surface coatings, can rapidly participate in the electrode dissolution-redeposition process and facilitate the establishment of the dissolution-redeposition equilibrium, thereby alleviating W net dissolution, modulating the electrode morphology, and improving the Coulombic efficiency and cycling stability during long-term electrochemical reactions. Therefore, our systematic study demonstrates that it is feasible to exploit the intertwined dissolution-redeposition kinetics between oxide surface coatings and electrodes in aqueous electrolytes to extend control over electrochemical interfacial reactions. Electrode surface chemistry can be re-synthesized in terms of regulating the dynamic structural evolution of electrode surface and the correlatively developing speciation at the interface, which highlights the significance of more fundamental investigations at the electrode-electrolyte interfaces.

Kelin Chen,1 Yuni Luo,1 Anyang Hu,2 Ji Zhao,3 Liwei Zhang4 1Institute of Urban Governance, Shenzhen University, Shenzhen, 518060, People’s Republic of China; 2School of Government, University of Chinese Academy of Social Science, Beijing, 102488, People’s Republic of China; 3School of International and Public Affairs, Shanghai Jiao Tong University, Shanghai, 200030, People’s Republic of China; 4School of Public Administration, Jilin University, Changchun, 130012, People’s Republic of ChinaCorrespondence: Liwei ZhangSchool of Public Administration, Jilin University, 2699 Qianjin Street, Changchun, 130012, People’s Republic of ChinaEmail zhanglw@jlu.edu.cnBackground: During a public health emergency, social media is a major conduit or vector for spreading health misinformation. Understanding the characteristics of health misinformation can be a premise for rebuking and purposefully correcting such misinformation on social media.Methods: Using samples of China’s misinformation on social media related to the COVID-19 outbreak (N=547), the objective of this article was to illustrate the characteristics of said misinformation on social media in China by descriptive analysis, including the typology, the most-mentioned information, and a developmental timeline.Results: The results reveal that misinformation related to preventive and therapeutic methods is the most-mentioned type. Other types of misinformation associated with people’s daily lives are also widespread. Moreover, cultural and social beliefs have an impact on the perception and propaganda of misinformation, and changes in the crisis situation are relevant to the type variance of misinformation.Conclusion: Following research results, strategies of health communication for managing misinformation on social media are given, such as credible sources and expert sources. Also, traditional beliefs or perceptions play the vital role in health communication. To sum up, combating misinformation on social media is likely not a single effort to correct misinformation or to prevent its spread. Instead, scholars, journalists, educators, and citizens must collaboratively identify and correct any misinformation.Keywords: health misinformation, social media, public health emergency, health communication, COVID-19, China

We report that electrocatalytic water decomposition can be leveraged to enhance the performance of aqueous batteries. Using the NaxFe[Fe(CN)6]ǁNaTi2(PO4)3 aqueous battery as a platform, we demonstrate that electrocatalytic water oxidation can serve as an electrochemical activation approach to achieving higher full cell capacity.

The electrode–electrolyte interfacial chemistry determines the durability of electrochromic devices. The long‐term cycling stability of transition metal (TM) oxide electrochromic films in the acidic electrolyte is impoverished, which is a major obstacle towards deep market penetration through sustainable and cost-effective smart windows. The research interest in nanostructuring TM oxide films to improve electrochromic performance has grown rapidly. However, there are few fundamental studies that investigate the mechanism of electrochromic degradation. In this work, we revisit the classical tungsten trioxide (WO3) materials as the platform to uncover the previously unknown interrelationship between morphological evolution, phase transformation, nanoscale color heterogeneity, and durability in these electrochromic materials. Through synchrotron spectroscopic, microscopic, and imaging characterizations, we experimentally reveal that tungsten dissolution/redeposition and proton-trapping are the two fundamental origins for performance degradation. The WO3–electrolyte interface is reshaped due to the metal dissolution and redeposition during electrochemical cycling. The recurrent redeposition process provokes the in situ crystal growth, which ultimately leads to the phase transformation from the semicrystalline WO3 to a nanoflake-shaped, proton-trapped tungsten trioxide dihydrate (H x WO3·2H2O). Besides, the heterogeneous proton trapping during long-term electrochemical cycling brings about the charge heterogeneity of thin-film electrodes, which further creates a significant degree of nanoscale color heterogeneity. The interaction between phase transformation, morphological evolution, and nanoscale color heterogeneity results in degraded cycling durability, including inferior optical modulation, switching kinetics, coulombic efficiency, and bleached-state transparency. Our work highlights that the high interfacial reactivity near the electrode surface may be the underlying mechanism for undesired bulk structural changes of electrochromic materials. The overwhelming morphological changes reported here may raise concerns about the legitimacy of a large body of literature that attributes the electrochromic performance solely to initial nanostructure design. More fundamental studies are needed to probe and control the interfacial chemistry in electrochromic and other electrochemical devices.

The porous polyvinylalcohol (PVA) hydrogel was prepared by chemical crosslinking in the saturated boric acid solution with sodium bicarbonate (SBC) as porogen. It was found that addition of SBC decreased the mechanical strength of the gel beads, while the gel permeability was improved. The equilibrium swelling rate and the swelling rate constant k of gel beads increased significantly by addition of SBC. Most of water in PVA hydrogel was in the form of free water and freezing bound water. With increasing SBC content, the total water content of the gel increased, in which the free water content increased remarkably, due to the formation of a large number of pores, and in the meantime, n values, characterizing the mole content of non-freezing bound water, were also improved greatly, indicating of the enhancement of the interaction between PVA molecules and water molecules. SEM observation showed that by adding SBC, many pores formed on the surface and inside gels, which provided channels for microbial metabolites. Microorganism could be successfully entrapped in the porous PVA beads, and addition of SBC made COD removal rate of the gel beads increase significantly.

This paper presents an embedded terminal design based on ARM11 to implement multimedia information sharing and relay transmission between wireless terminal devices. Multimedia collection and wireless transmission to each other are easy to be realized based on an embedded board combined with a CMOS camera module and a SDIO wifi module. After the procedure of installation of cross complier on PC, and transplantation of bootloader, linux kernel and file system on board, through programming application based on V4L2, the camera can be controlled to capture a picture, which is compressed into jpeg format by calling libjpeg, another application is applied to wirelessly send pictures to each other through TCP socket network programming between two embedded devices. This design can widely be used in fields like modern security, monitor system for safety production, cloud camera and so on. Keywords-ARM11; multimedia collection and wireless transmission; V4L2; libjpeg; socket