The wide spectral range of the solar flux with undesirable diffused energy distribution remains a substantial impediment to the high‐efficiency utilization of the whole spectrum. Here, inspired by ...the spectrally selective sunlight utilization of plants, a spectrum‐tailored solar harnessing aerogel is conceived. It is composed of oxygen vacancy (Ov) defect‐rich semiconductor HNb3O8 (D‐HNb3O8) nanosheets and polyacrylamide (PAM) framework to perform all‐in‐one photochemical and photothermal full solar energy conversion. The aerogel selectively utilizes the whole solar spectrum, in which high energy ultraviolet (UV) photon is converted into high redox potential electron–hole pairs, while low energy visible‐near infrared (NIR) photons are transformed into heat. The designed solar absorber‐polymer composite shows energy harnessing‐conversion capability with desired heat insulation, reactant enrichment, rapid mass diffusion and capillary pumping characteristics, thus realizing a high efficient steam generation and photochemical activity. This cooperative photochemical and photothermal solar energy conversion, at respective optimal working spectrum, holds great promise for optimizing and maximizing the solar energy utilization, as well as opening up opportunities to explore simultaneous multifunctional usage of solar energy.
A spectrum‐tailored solar harnessing aerogel is conceived. It selectively utilizes the whole solar spectrum, in which high energy ultraviolet photons are converted into high redox potential electron–hole pairs to drive photochemical conversion, while low energy visible‐near infrared photons are transformed into heat to drive photothermal evaporation, thereby optimally utilizing the full solar spectrum with high conversion efficiency.
At present, the technological groundwork of atomically thin two-dimensional (2D) hetero-layered structures realized by successive thin film epitaxial growth is in principle constrained by lattice ...matching prerequisite as well as low yield and expensive production. Here, we artificially coordinate ultrathin 2D hetero-layered metal chalcogenides via a highly scalable self-surface charge exfoliation and electrostatic coupling approach. Specifically, bulk metal chalcogenides are spontaneously exfoliated into ultrathin layers in a surfactant/intercalator-free medium, followed by unconstrained electrostatic coupling with a dissimilar transition metal dichalcogenide, MoSe
, into scalable hetero-layered hybrids. Accordingly, surface and interfacial-dominated photocatalysis reactivity is used as an ideal testbed to verify the reliability of diverse 2D ultrathin hetero-layered materials that reveal high visible-light photoreactivity, efficient charge transfer and intimate contact interface for stable cycling and storage purposes. Such a synthetic approach renders independent thickness and composition control anticipated to advance the development of 'design-and-build' 2D layered heterojunctions for large-scale exploration and applications.
This paper presents the in situ mapping of temperature-dependent lithium-ion diffusion at the nanometer level in thin film Li1.2Co0.13Ni0.13Mn0.54O2 cathode using electrochemical strain microscopy. ...The thin-film Li1.2Co0.13Ni0.13Mn0.54O2 cathode exhibits higher lithium-ion diffusivities with increasing temperature, which explains the higher capacity observed in the lithium-ion batteries with a Li-rich cathode at elevated temperature. In addition, the activation energy for lithium-ion diffusion can be extracted in an Arrhenius-type plot at the level of grain structure with the assumption that the ionic movement is diffusion controlled. Compared with the grain interiors, the grain boundaries show relatively lower activation energy; hence, it is the preferred diffusion path for lithium ions. This study has bridged the gap between atomistic calculations and traditional macroscopic experiments, showing direct evidence as well as mechanisms for ionic diffusion for Li-rich cathode material.
Freestanding functional inorganic membranes, beyond the limits of their organic and polymeric counterparts
, may unlock the potentials of advanced separation
, catalysis
, sensors
, memories
, ...optical filtering
and ionic conductors
. However, the brittle nature of most inorganic materials, and the lack of surface unsaturated linkages
, mean that it is difficult to form continuous membranes through conventional top-down mouldings and/or bottom-up syntheses
. Up to now, only a few specific inorganic membranes have been fabricated from predeposited films by selective removal of sacrificial substrates
. Here we demonstrate a strategy to switch nucleation preferences in aqueous systems of inorganic precursors, resulting in the formation of various ultrathin inorganic membranes at the air-liquid interface. Mechanistic study shows that membrane growth depends on the kinematic evolution of floating building blocks, which helps to derive the phase diagram based on geometrical connectivity. This insight provides general synthetic guidance towards any unexplored membranes, as well as the principle of tuning membrane thickness and through-hole parameters. Beyond understanding a complex dynamic system, this study comprehensively expands the traditional notion of membranes in terms of composition, structure and functionality.
High-resolution real-space mapping of Li-ion diffusion in the LiNi1/3Co1/3Mn1/3O2 cathode within an all-solid-state thin film Li-ion battery has been conducted using advanced scanning probe ...microscopy techniques, namely, band excitation electrochemical strain microscopy (BE-ESM) and conductive atomic force microscopy. In addition, local variations of the electrochemical response in the LiNi1/3Co1/3Mn1/3O2 thin film cathode at different cycling stages have been investigated. This work demonstrates the unique feature and applications of the BE-ESM technique on battery research. The results allow us to establish a direct relationship of the changes in ionic mobility as well as the electrochemical activity at the nanoscale with the numbers of charge/discharge cycles. Furthermore, various factors influencing the BE-ESM measurements, including sample mechanical properties (e.g., elastic and dissipative properties) as well as surface electrical properties, have also been studied to investigate the coupling effects on the electrochemical strain. The study on the relationships between the Li-ion redistribution and microstructure of the electrode materials within thin film Li-ion battery will provide further understanding of the electrochemical degradation mechanisms of Li-ion rechargeable batteries at the nanoscale.
Considering that there is a shortage of sustainable resources and that serious environmental issues need to be solved, the development of efficient catalysts has attracted a lot attention globally ...for energy saving and environmental improvement. In the last few decades, great progresses have been made in terms of fabrication and application of catalysts, however, systematic characterization with advanced technology and methods that enable researchers to have a detailed understanding of the catalysts’ properties and catalytic reactions, especially where an interface is present, are still limited. This Review focusses on the applications of advanced Scanning Probe Microscopy (SPM) and Spectroscopy techniques for the characterization of catalytic materials and their related reactions. A detailed description of advanced SPM and Spectroscopy techniques is introduced, followed by their applications in the characterization of surfaces and properties of common ordered catalytic materials including some coordination polymers and metal oxides. Various properties of these catalytic materials, such as conductivity, piezoelectricity, nanomechanics, photoresponse, and others, characterized by SPM and Spectroscopy are discussed. Subsequently, we introduce the high‐resolution imaging of chemical reactions and bond configuration by high‐resolution non‐contact Atomic Force Microscopy (NC‐AFM). Finally, the challenges involved in the development of SPM and Spectroscopy and an outlook for future research are presented. This Review provides fundamental insights into the characterization of heterogeneous catalysts and viewpoints to the development of smart catalytic materials.
Take a closer look: This Review focusses on the applications of advanced Scanning Probe Microscopy (SPM) and Spectroscopy techniques for the characterization of catalytic materials and their related reactions. A detailed description of the techniques is introduced, followed by their applications in the characterization of surfaces and properties of common ordered catalytic materials including some coordination polymers and metal oxides.
The effect of relative humidity on the domain structure imaging and polarization switching process of Pb(Zn1/3Nb2/3)O3-x%PbTiO3 (PZN-x%PT) ferroelectric single crystals has been investigated by means ...of the piezoresponse force microscopy (PFM) and piezoresponse force spectroscopy (PFS) techniques. It was found that the PFM amplitude increases with the relative humidity, and that the ferroelectric hysteresis loops at different relative humidity levels show that the coercive bias decreases with the increase in relative humidity. These observed phenomena are attributed to the existence of the water layer between the probe tip and the sample surface in a humid atmosphere, which could affect the effect of the electric field distribution and screening properties at the ferroelectric sample surface. These results provide a better understanding of the water adsorption phenomena at the nanoscale in regard to the fundamental understanding of ferroelectrics’ properties.
The evolution of the domain structures of 001-oriented relaxor ferroelectric 0.93PbZn1/3Nb2/3O3-0.07PbTiO3 (PZN-7%PT) single crystals as a function of temperature was investigated in situ by using ...piezoresponse force microscopy (PFM). It was found that the local domain structure of PZN-7%PT single crystals at room temperature is rhombohedral with nanoscale twins. Temperature-dependent domain structures showed that the phase transition process is a collective process and that the sample underwent a sequence of rhombohedral (R) → monoclinic (Mc) → tetragonal (T) → cubic (C) phase transformations when the temperature increased from 25 °C to 170 °C. The results provide direct observation of the phase transition evolution of PZN-7%PT single crystals as a function of temperature, which is of great significance to fully understand the relationships between the domain structure and phase structure of PZN-7%PT single crystals.
Generation of large strains upon Na
+
intercalation is one of the prime concerns of the mechanical degradation of Prussian blue (PB) and its analogs. Structural construction from the atomic level is ...imperative to maintain structural stability and ameliorate the long-term stability of PB. Herein, an inter nickel hexacyanoferrate (NNiFCN) is successfully introduced at the out layer of iron hexacyanoferrate (NFFCN) through ion exchange to improve structural stability through compressive stress locking by forming NNiFCN shell. Furthermore, the kinetics of sodium ion diffusion is enhanced through the built-in electric pathway. The electrochemical performance is therefore significantly improved with a remarkable long-term cycling stability over 3,000 cycles at 500 mA·g
−
1
in the full sodium-ion batteries (SIBs) with a maximum energy density of 91.94 Wh·g
−
1
, indicating that the core-shell structured NNiFCN/NFFCN could be the low-cost and high-performance cathode for full SIBs in large-scale EES applications.
Resistive switching phenomena form the basis of competing memory technologies. Among them, resistive switching, originating from oxygen vacancy migration (OVM), and ferroelectric switching offer two ...promising approaches. OVM in oxide films/heterostructures can exhibit high/low resistive state via conducting filament forming/deforming, while the resistive switching of ferroelectric tunnel junctions (FTJs) arises from barrier height or width variation while ferroelectric polarization reverses between asymmetric electrodes. Here the authors demonstrate a coexistence of OVM and ferroelectric induced resistive switching in a BaTiO3 FTJ by comparing BaTiO3 with SrTiO3 based tunnel junctions. This coexistence results in two distinguishable loops with multi‐nonvolatile resistive states. The primary loop originates from the ferroelectric switching. The second loop emerges at a voltage close to the SrTiO3 switching voltage, showing OVM being its origin. BaTiO3 based devices with controlled oxygen vacancies enable us to combine the benefits of both OVM and ferroelectric tunneling to produce multistate nonvolatile memory devices.
The coexistence of oxygen‐vacancy migration and ferroelectric‐induced resistive switching in BaTiO3 ferroelectric tunnel junctions through several sets of comparison between BaTiO3‐ and SrTiO3‐ based tunnel junctions is described. This coexistence results in two distinguishable loops with multi‐nonvolatile resistive states in a single device, showing that controlling oxygen vacancies is an effective way to produce multistate memory devices.
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