Because of the popularity of smart electronics, multifunctional energy storage devices, especially electrochromic supercapacitors (SCs), have attracted tremendous research interest. Herein, a solid-state electrochromic asymmetric SC (ASC) window is designed and fabricated by introducing WO and polyaniline as the negative and positive electrodes, respectively. The two complementary materials contribute to the outstanding electrochemical and electrochromic performances of the fabricated device. With an operating voltage window of 1.4 V and an areal capacitance of 28.3 mF cm, the electrochromic devices show a high energy density of 7.7 × 10 mW h cm. Meanwhile, they exhibit an obvious and reversible color transition between light green (uncharged state) and dark blue (charged state), with an optical transmittance change between 55 and 12% at a wavelength of 633 nm. Hence, the energy storage level of the ASC is directly related to its color and can be determined by the naked eye, which means it can be incorporated with other energy cells to visual display their energy status. Particularly, a self-powered and color-indicated system is achieved by combining the smart windows with commercial solar cell panels. We believe that the novel electrochromic ASC windows will have great potential application for both smart electronics and smart buildings.

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Tungsten oxide has been recently demonstrated interesting and promising bifunctionalities that combine electrochromism and pseudocapacitance. However, understanding about the charge storage process of pseudocapacitive tungsten oxide film is very limited. Our quantitative investigation clearly reveals that the capacity performance of tungsten oxide film is thickness-dependent. In particular, the 100 nm-thick tungsten oxide film exhibits highest charge capacity density at high rates, with nearly 242.1 C g −1 stored reversibly in 6 s. The 100 nmthick tungsten oxide film stores charges mainly by capacitive effects (including both electric double layer capacitance and pseudocapacitance). For example, at a scan rate of 5 mV s −1 , more than 78% stored charges is attributed to capacitive effects, according to the cyclic voltammetry analysis. Furthermore, pseudocapacitance is responsible for around 70% of the capacitive charge storage based on the electrochemical impedance spectroscopy analysis. The contributions of diffusion-controlled process, electric double layer capacitive process, and pseudocapacitive process have been discussed in detailed and successfully identified. Overall, this work provides insight into the charge storage process of tungsten oxide, and our new findings can shed light on other transition metal oxide-based electrochemical energy storage systems.

BackgroundSignificant growth has been observed in the field of foot and ankle research in recent years. However, bibliometric studies concerning the quantity and quality of articles published in foot and ankle journals are scarce. This study aimed to reveal the characteristics of national productivity in the field of foot and ankle research and to provide a general picture of foot and ankle research for surgeons and researchers.MethodsWeb of Science was searched for foot and ankle articles in 4 highly cited journals from 2009 to 2013. The number of total articles and citations were collected to evaluate the contribution of different countries. Publication activity was adjusted for the countries by population size and gross domestic product (GDP).ResultsA total number of 2083 articles were published worldwide. North America, West Europe, Australia and East Asia were the most productive world regions. High income countries published 90.35% of articles, middle-income 9.60%, and low-income just 0.05%. The United States published the largest number of articles (1025/2083, 49.2%), followed by the United Kingdom (221/2083, 10.6%), Australia (92/2083, 4.4%), and had the highest total citations (3631). However, Canada had the highest average citations per article (5.0), followed by Australia (4.6) and Switzerland (4.2). There were positive correlations between the total number of publications and population/GDP (p < 0.01). When normalized to population size, Switzerland ranked the highest, followed by Australia, and the United Kingdom. When adjusted for GDP, Switzerland ranked the highest, followed by United Kingdom, and South Korea.ConclusionsThe United States is the most productive country in the field of foot and ankle research. However, Australia, some smaller European and Asian countries may be more productive relative to their size.