Hierarchically Porous Carbon Photonic Structures

Abstract

Hierarchically porous carbon holds promise for many applications involving not only electrical, catalytic, power storage and related functionalities but, despite absorption in the visible and near-infrared, also optical and sensing uses are envisaged. In this paper, the self-assembly of heterogeneous coreshell and hollow carbon spheres based on polystyrene cores, their optical properties and their response to humidity are described. The remarkable high quality of the crystals permits to exploit their singular optical properties among which a very high sensitivity to adsorption of guest materials stands out. In this regard, an original characterization of the system response is performed by means of the photonic bandgap variation with the relative gas pressure. Controlled pyrolysis enables to create and tune the features of the porosity brought about by degassing and the restructuring of the carbon lattice. Functionality associated with diverse pore populations reveals sensitivity to diverse ranges of humidity owing to selective adsorption of water in different size pores.

Humidity‐Induced Simultaneous Visible and Fluorescence Photonic Patterns Enabled by Integration of Covalent Bonds and Ionic Crosslinks

“…It is generally observed from the materials possessing spatial periodicity, which names photonic crystals (PC). [ 1–2 ] Different from the color from dyes or pigments that suffers from the photobleaching, structural color presents excellent iridescent and angular‐dependence, enabling the PCs, especially stimuli‐responsive PCs able to change the reflective color under external stimulations, applicable in researches of biomedical analysis, [ 3–5 ] sensors, [ 6–8 ] optical devices, [ 9–12 ] and anti‐counterfeiting. [ 13–15 ] Among the abundant of the responsive PCs, invisible PC patterns that hiding the information under normal state but showing under external stimulations have drawn intense scientific interests because of the great potentials in information storage, anti‐counterfeiting, and decorations.…”

A Strategy of Bifunctional Nanoscale Melamine‐Resin Sphere Template to Fabricate Porous Carbons

“…[ 2,9,10 ] As an important pore‐forming approach, the hard template method was widely implemented for the fabrication of porous carbons. [ 2,11–18 ] The usual hard templates such as silica nanoparticle, mesoporous silica, and polystyrene sphere exhibit nanoscale particle diameter or pore size, which facilitate the resulting carbons to obtain hierarchical pore structures and high specific surface area. [ 13–16 ] On the other hand, the heteroatoms of porous carbons remarkably boost their performances.…”

“…[ 2,11–18 ] The usual hard templates such as silica nanoparticle, mesoporous silica, and polystyrene sphere exhibit nanoscale particle diameter or pore size, which facilitate the resulting carbons to obtain hierarchical pore structures and high specific surface area. [ 13–16 ] On the other hand, the heteroatoms of porous carbons remarkably boost their performances. [ 19–21 ] Many incorporation strategies of the heteroatoms have been carried out to regulate the structure of porous carbons, thus remarkably improving their performances.…”

Silicon‐Based Photonic Architectures from Hierarchically Porous Carbon Opals

“…In this work, we demonstrate the fabrication of up to five types of hybrid C-Si and pure Si hierarchical structures starting from a 3D ordered template based on hollow carbon spheres, that is, a hollow carbon opal (HCO). 22,24 Its selection as the starting material relies on its advantageous features to generate novel and improved architectures, conveniently combining properties in different areas of application such as: i) Hierarchical porosity comprised of uniform, spherical macropores (the empty space inside the spheres), mesopores (the interstices between the spheres) and micropores (induced in the carbon shell by pyrolysis). Additionally, the HCO is a versatile system as it allows broad variation of fabrication parameters, such as the macropore size (from 500 to 900 nm), the shell thickness (from 20 to 210 nm) and the shell microporosity.…”

“…22 ii) Photonic properties arising from the highly ordered fcc crystalline array formed by the spheres showing an intense Bragg peak (the lowest-energy photonic bandgap). 24 This property not only allows applicability in photonics (as a sensitive platform for sensing for instance) but also constitutes a powerful diagnostic tool to follow the changes undergone by the structure along the fabrication process.…”