Powerful Dehalogenation Tool: A Simple Route To Graft Carbon Materials With Well-Defined Open Pores

Porous carbon materials (PCMs) hold great scientific and technological importance due to their ability to allow gases and liquids to penetrate their entire bulk.(1) They have been long regarded as key components for building up sustainable and clean energy technologies such as fuel cells, rechargeable batteries, supercapacitors, etc.(2) Especially, PCMs with open pores (including mesopores, macropores, and larger-sized pores) are more attractive in the abovementioned fields because open pores are able to provide fast communication between bulk medium and inner interfaces of PCMs.(3)

Despite their abundant resources and low costs, the synthetic strategies for PCMs have been mostly founded based on condensation of organic matters that are functionalized with H-, O-, N-, or S-moieties, followed by activation steps.(4) However, the energy for activating these bonds are usually very high, leaving some tough issues such as high-energy in demand, a large quantity of hazardous gas byproducts emitted, and hard control on structure and porosity.(4) Mostly, in order to introduce controllable meso-/macro-pores, solid or liquid templates with narrow size distributions are required.

To meet these ends, we have developed a novel strategy that enables fast fabrication of carbon materials under mild conditions. For instance, carbonaceous materials can be obtained in 60 seconds via dehalogenation of polyvinyl dichloride (PVDC) by KOH at room temperature, no hazardous byproduct was formed.(5) Meanwhile, following studies revealed that the dehalogenation strategy is applicable for the tunable synthesis of carbon materials with largely varied dopant types (N, S, P, O, or their combinations)(6-8), morphologies (sheet, crump, foam, etc) (5, 9, 10), and most importantly, widely tuned porosity(11, 12).

In this work, hierarchically porous carbon (HPC) materials with well-defined meso-/macro-pores are obtained via the dehalogenation reaction of polyvinyl difluoride (PVDF) by NaNH2. The mechanism of carbon formation is described by Eq. (1), accordingly, two important byproducts of NaF and NH3 are formed, which are applicable for in situ templating and bubbling intermediate carbon structure for meso-/macro-pores. Meanwhile, the intentionally left NaNH2 can further activate carbon for abundant microporosity (Eq. (2)). Electron microscopy studies and Brunauer–Emmett–Teller (BET) measurements confirmed that the structures of HPC samples contain multiple-scale pores assembled in a hierarchical pattern, and most of their volumes are contributed by mesopores, as displayed in Figure 1.

We managed to synthesize two types of HPC materials, the synthesis of HPC-7 followed the protocol mentioned above, the other one: HPC-M7 with much larger macropores was obtained by adding decomposable and vaporable component (melamine) before the dehalogenation reaction initiated. This specific finding relating secondary vaporable component may enable powerful tuning on pore types and their ratios of porous carbon materials.

Figure 1. Electron microscopy and BET characterizations on HPC materials. (Used with permission from Guoxin Zhang)

Improving specific energy of supercapacitors (SCs) at high power has been intensively investigated as a hot and challengeable topic. As for demonstration, HPC-M7 with abundant well-defined open pores as well as micropores was fabricated into aqueous symmetric supercapacitors (ASSCs). Electrochemical measurements revealed that HPC-M7 achieved an ultrahigh specific energy of 19 Wh kg-1 at the specific power of ~1 kW kg-1. Remarkably, at the ultrahigh power of 14 kW kg-1, the HPC-M7-ASSCs still delivered a very high specific energy of 17 Wh kg-1, meaning that the HPC-M7-ASSCs can be charged or discharged within 4 s.

These findings are described in the article entitled Fabricating Hierarchically Porous Carbon with Well-Defined Open Pores via Polymer Dehalogenation for High-Performance Supercapacitor recently published in the journal Applied Surface Science. This work was conducted by Mei Guo, Yu Li, Kewen Du, Chaochao Qiu, Gang Dou, and Guoxin Zhang from Shandong University of Science and Technology.

About The Author

Guoxin Zhang

Guoxin is a research scientist at the Shandong University of Science and Technology, Electrical Engineering and Automation.

Speak Your Mind!


Map Of Italy And Greece

When looking at a map of Italy and Greece you can tell both countries are amazingly beautiful with a lot of gorgeous cities and towns. Both countries are situated along the Ionian Sea so, the beautiful coastlines stretch far across both countries and are home to many people. To learn all about the maps of […]

Integer Aperture Estimation In The Presence Of Biases

Integer aperture estimation, also called integer ambiguity resolution, is a critical step to realized fast and precise global navigation satellite system (GNSS) positioning. It is a process which projects a float ambiguity to an integer ambiguity and then judges whether to fix that integer. Decades of research offer many projection methods. Efficiency and success rate […]

Wind Scorpion

The wind scorpion is a colloquial name for a group of arthropods under the order Solifugae in the class Arachnida. Also known as sun spiders or camel spiders, the order Solifugae includes over 1,000 individual species of arthropod spread over 153 genera. Contrary to their popular names, wind scorpions are neither true scorpions nor true spiders, but […]

Dispersion And Distortion In Decamethylmetallocenes

Bonding between atoms can take a variety of forms, but ionic bonding is conceptually one of the most straightforward. It involves the attraction between positively (cationic) and negatively (anionic) charged ions, such as occurs between sodium ions (Na+) and chloride ions (Cl–) in table salt (NaCl). These bonds are often quite strong (i.e., NaCl is […]

Urban Modeling For Large-Scale Assessment Of Building Energy Efficiency Improvements

More than two-thirds of people in the U.S. live in urban areas, which are facing huge challenges related to retrofit, expansion and operational efficiency to reduce resource use and greenhouse gas (GHG) emissions, and to meet sustainability goals and resiliency to combat nature extreme events and emergencies. Buildings in U.S. cities consume up to 70% […]

David Bowie’s Eyes: Anisocoria

David Bowie’s eyes are two different colors due to Anisocoria, this is a result of a permanently dilated pupil which makes one iris color look different from the other in David Bowie’s eyes. This is what gave him the eerie black and light blue colored eye. We see the world through our eyes. To many, […]

Preparing The Field To Avoid A Volcanic Disaster By Means Of Numerical Modeling At Tacaná Volcano

Volcanoes are often seen as agents of destruction and catastrophes when they present major eruptive activity such as continuous lava flows, sustained vertical eruptive columns of ash and gases, mudflows in the form of lahars, and pyroclastic density currents (i.e. pyroclastic flows, PFs), which are a super-hot mix of ash, rocks, and gas (>300°C) that […]