11 research outputs found

    Cognitive Alignment through Artefacts in Distributed Innovation: The Role of Initial Code Release in Open Source Software

    No full text
    We present results from density functional theory calculations of the lithium adsorption onto 2D graphitic carbon nitride membranes, C<sub>3</sub>N<sub>4</sub> and C<sub>6</sub>N<sub>8</sub> and bulk C<sub>3</sub>N<sub>4</sub>. We find that lithium adsorbs preferentially over the triangular pores with a high adsorption energy. We also find that lithium adsorption severely distorts the membrane and bulk material. The lithium mainly interacts with the pyridinic nitrogen in the material, which enables a large lithium uptake. However, the pyridinic nitrogen is also responsible for the instability of the material. We also present experimental results on the charge and discharge capacities of C<sub>6</sub>N<sub>8</sub>. These mirror the theoretical prediction that the material shows a high lithium uptake which is, however, irreversible

    Pyrene-Functionalized PTMA by NRC for Greater π–π Stacking with rGO and Enhanced Electrochemical Properties

    No full text
    Nitroxide radical polymers can undergo both excellent electrochemical redox reactions and a rapid “click” coupling reaction with carbon-centered radicals (i.e., nitroxide radical coupling (NRC) reaction). In this work, we report a strategy to functionalize poly­(2,2,6,6,-tetramethylpiperidinyl-1-oxyl methacrylate) (PTMA) with pyrene side groups through a rapid and near quantitative NRC reaction. This resulted in P­(TMA-<i>co</i>-PyMA) random copolymers with near quantitative amounts of pyrene along the PTMA chain for greater π–π interaction with rGO, while the nitroxide radicals on the polymer could simultaneously be used for energy storage. These copolymers can bind with reduced graphene oxide (rGO) and form layered composites through noncovalent π–π stacking, attaining molecular-level dispersion. Electrochemical performance of the composites with different polymer contents (24, 35, and 45 wt %), tested in lithium ion batteries, indicated that the layered structures consisting of P­(TMA-<i>co</i>-PyMA) maintained greater capacities at high C-rates. This simple and efficient strategy to synthesize pyrene-functionalized polymers will provide new opportunities to fabricate many other polymer composite electrodes for desired electrochemical performance

    Transition from the Tetragonal to Cubic Phase of Organohalide Perovskite: The Role of Chlorine in Crystal Formation of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> on TiO<sub>2</sub> Substrates

    No full text
    The role of chlorine in the superior electronic property and photovoltaic performance of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>(3–<i>x</i>)</sub>Cl<sub><i>x</i></sub> perovskite has attracted recent research attention. Here, we study the impact of chlorine in the perspective of the crystal structure of the perovskite layer, which can provide important understanding of its excellent charge mobility and extended lifetimes. In particular, we find that in the presence of chlorine (PbCl<sub>2</sub> or CH<sub>3</sub>NH<sub>3</sub>Cl), when CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> films are deposited on a TiO<sub>2</sub> mesoporous layer instead of a planar TiO<sub>2</sub> substrate, a stable cubic phase rather than the commonly observed tetragonal phase is formed in CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> perovskite at room temperature. The relative peak intensity of two major facets of cubic CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> crystals, (100)<sub>C</sub> and (200)<sub>C</sub> facets, can also be easily tuned, depending on the film thickness. Furthermore, compared with pristine CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> perovskite films, in the presence of chlorine, CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> crystals grown on planar substrates exhibit strong preferred orientations on (110)<sub>T</sub> and (220)<sub>T</sub> facets

    Facile Synthesis of Highly Efficient One-Dimensional Plasmonic Photocatalysts through Ag@Cu<sub>2</sub>O Core–Shell Heteronanowires

    No full text
    A novel class of one-dimensional (1D) plasmonic Ag@Cu<sub>2</sub>O core–shell heteronanowires have been synthesized at room temperature for photocatalysis application. The morphology, size, crystal structure and composition of the products were investigated by XRD, SEM, TEM, XPS, and UV–vis instruments. It was found the reaction time and the amount of Ag nanowires play crucial roles in the formation of well-defined 1D Ag@Cu<sub>2</sub>O core–shell heteronanowires. The resultant 1D Ag@Cu<sub>2</sub>O NWs exhibit much higher photocatalytic activity toward degradation of organic contaminants than Ag@Cu<sub>2</sub>O core–shell nanoparticles or pure Cu<sub>2</sub>O nanospheres under solar light irradiation. The drastic enhancement in photocatalytic activity could be attributed to the surface plasmon resonance and the electron sink effect of the Ag NW cores, and the unique 1D core–shell nanostructure

    Hollow Anatase TiO<sub>2</sub> Single Crystals and Mesocrystals with Dominant {101} Facets for Improved Photocatalysis Activity and Tuned Reaction Preference

    No full text
    Faceting photocatalysts has attracted increasing interest to improve photocatalytic activity by optimizing surface charge carrier separation/transfer. In principle, a high photocatalytic activity is co-contributed by both high surface separation/transfer and low bulk recombination of charge carriers. However, little effort focuses on lowering bulk recombination of charge carriers in faceted photocatalysts. In this work, we report the synthesis of hollow anatase TiO<sub>2</sub> single crystals and mesocrystals with dominant {101} facets by a new route with PO<sub>4</sub><sup>3–</sup>/F<sup>–</sup> as morphology controlling agent. It is found that with respect to solid crystals, being hollow crystals and mesocrystals can substantially improve photocatalytic activity (O<sub>2</sub>/H<sub>2</sub> evolution from water splitting, CH<sub>4</sub> generation from photoreduction of CO<sub>2</sub>) as a result of the synergistic effects of shortened bulk diffusion length of carriers for the decreased bulk recombination and increased surface area. Furthermore, the photocatalysis reaction preference toward O<sub>2</sub> and H<sub>2</sub> evolution from water splitting can be tuned

    Porous Titania Nanosheet/Nanoparticle Hybrids as Photoanodes for Dye-Sensitized Solar Cells

    No full text
    Porous titania nanohybrids (NHs) were successfully prepared by hybridizing the exfoliated titania nanosheets with anatase TiO<sub>2</sub> nanoparticles. Various characterizations revealed that the titania NHs as photoanodes play a trifunctional role (light harvesting, dye adsorption, and electron transfer) in improving the efficiency (η) of the dye-sensitized solar cells. The optimized photoanode consisting layered NHs demonstrated a high overall conversion efficiency of 10.1%, remarkably enhanced by 29.5% compared to that (7.8%) obtained from the benchmark P25 nanoparticles under the same testing conditions

    Liquid-Metal-Induced Hydrogen Insertion in Photoelectrodes for Enhanced Photoelectrochemical Water Oxidation

    No full text
    Fast charge separation and transfer (CST) is essential for achieving efficient solar conversion processes. This CST process requires not only a strong driving force but also a sufficient charge carrier concentration, which is not easily achievable with traditional methods. Herein, we report a rapid hydrogenation method enabled by gallium-based liquid metals (GBLMs) to modify the prototypical WO3 photoelectrode to enhance the CST for a PEC process. Protons in solution are controllably embedded into the WO3 photoanode accompanied by electron injection due to the strong reduction capability of GBLMs. This process dramatically increases the carrier concentration of the WO3 photoanode, leading to improved charge separation and transfer. The hydrogenated WO3 photoanode exhibits over a 229% improvement in photocurrent density with long-term stability. The effectiveness of GBLMs treatment in accelerating the CST process is further proved using other more general semiconductor photoelectrodes, including Nb2O5 and TiO2

    Oriented Built-in Electric Field Introduced by Surface Gradient Diffusion Doping for Enhanced Photocatalytic H<sub>2</sub> Evolution in CdS Nanorods

    No full text
    Element doping has been extensively attempted to develop visible-light-driven photocatalysts, which introduces impurity levels and enhances light absorption. However, the dopants can also become recombination centers for photogenerated electrons and holes. To address the recombination challenge, we report a gradient phosphorus-doped CdS (CdS-P) homojunction nanostructure, creating an oriented built-in electric-field for efficient extraction of carriers from inside to surface of the photocatalyst. The apparent quantum efficiency (AQY) based on the cocatalyst-free photocatalyst is up to 8.2% at 420 nm while the H<sub>2</sub> evolution rate boosts to 194.3 μmol·h<sup>–1</sup>·mg<sup>–1</sup>, which is 58.3 times higher than that of pristine CdS. This concept of oriented built-in electric field introduced by surface gradient diffusion doping should provide a new approach to design other types of semiconductor photocatalysts for efficient solar-to-chemical conversion

    Liquid-Metal-Induced Hydrogen Insertion in Photoelectrodes for Enhanced Photoelectrochemical Water Oxidation

    No full text
    Fast charge separation and transfer (CST) is essential for achieving efficient solar conversion processes. This CST process requires not only a strong driving force but also a sufficient charge carrier concentration, which is not easily achievable with traditional methods. Herein, we report a rapid hydrogenation method enabled by gallium-based liquid metals (GBLMs) to modify the prototypical WO3 photoelectrode to enhance the CST for a PEC process. Protons in solution are controllably embedded into the WO3 photoanode accompanied by electron injection due to the strong reduction capability of GBLMs. This process dramatically increases the carrier concentration of the WO3 photoanode, leading to improved charge separation and transfer. The hydrogenated WO3 photoanode exhibits over a 229% improvement in photocurrent density with long-term stability. The effectiveness of GBLMs treatment in accelerating the CST process is further proved using other more general semiconductor photoelectrodes, including Nb2O5 and TiO2

    Oriented Built-in Electric Field Introduced by Surface Gradient Diffusion Doping for Enhanced Photocatalytic H<sub>2</sub> Evolution in CdS Nanorods

    No full text
    Element doping has been extensively attempted to develop visible-light-driven photocatalysts, which introduces impurity levels and enhances light absorption. However, the dopants can also become recombination centers for photogenerated electrons and holes. To address the recombination challenge, we report a gradient phosphorus-doped CdS (CdS-P) homojunction nanostructure, creating an oriented built-in electric-field for efficient extraction of carriers from inside to surface of the photocatalyst. The apparent quantum efficiency (AQY) based on the cocatalyst-free photocatalyst is up to 8.2% at 420 nm while the H<sub>2</sub> evolution rate boosts to 194.3 μmol·h<sup>–1</sup>·mg<sup>–1</sup>, which is 58.3 times higher than that of pristine CdS. This concept of oriented built-in electric field introduced by surface gradient diffusion doping should provide a new approach to design other types of semiconductor photocatalysts for efficient solar-to-chemical conversion
    corecore