Precursor derived nanostructured carbon ceramic hybrids for hydrogen storage

Ipsita P. Swain1*, Shantanu K. Behera2 1,2. Laboratory for New Ceramics, Department of Ceramic Engineering, National institute of

Technology, Rourkela, Odisha, India, 769008

*Corresponding Author: Ipsita P. Swain, Email: , Mob: +91 7064386883

Abstract Polymer-derived-ceramics (PDC) possess excellent physico-chemical characteristics,

including creep resistance, piezoresistivity, Li ion intercalability, and are processed from the

inert pyrolysis of Si-containing polymers. However, during pyrolysis, escape of organic

moieties followed by sintering results in low specific surface area (SSA) of the particulate

ceramics. Immense prospects lie for the use of these materials in the areas of adsorption, storage

and separation of gases (H2, CH4) if the SSA and porosity can be tailored to desired levels.

The current work explores a novel, yet versatile, method for the fabrication of a hybrid with a

nanostructured carbon as a template and the PDC as coating. The carbon template limits

shrinkage of the PDC leading to SSA of >250 m2/g, and average pore size <1.5 nm. Retention

of such high SSA and microporosity are important properties for sensing and adsorption.

Furthermore, the PDC silicon oxycarbide coating constitutes of nanostructured SiO2 domains

that can be leached out to enhance SSA to fabricate highly porous oxycarbide derived carbon.

Such carbon materials have shown SSA in excess of 916 m2/g with a major part of the porosity

being microporous. Interestingly the process is so generic that with subtle change in process

parameters, the SSA and pore size can be tailored. HRTEM imaging of the hybrids have shown

graphene-type carbon layers and clearly observable microporosity. Initial results of hydrogen

uptake of these hybrids have shown encouraging results. The interplay of process parameters

on the evolution of nanoporosity and nanostructure of the hybrids materials will be presented.

(Keywords: Polymer derived ceramics; hydrogen gas storage; microporosity; HRTEM)

*Behera@alum.lehigh.edu The authors would like to acknowledge SERB, DST, Government of India for financial assistance.

Laboratory for New Ceramics, Department of Ceramic Engineering, National Institute of Technology, Rourkela, Odisha, India, 769008

81st Annual session of Indian Ceramic Society and International conference on “Expanding Horizons of Technological Applications of Ceramics and Glasses“

Precursor derived nanostructured carbon ceramic hybrids for hydrogen storage

ABSTRACT :Polymer-derived-ceramics (PDC), during pyrolysis leads to escape of organic moieties followed by sintering results in low specific surface area (SSA) of theparticulate ceramics. The current work explores a novel, yet versatile, method for the fabrication of a hybrid with a nanostructured carbon as a template and the PDC ascoating. The carbon template limits shrinkage of the PDC leading to SSA of >250 m2/g, and average pore size <1.5 nm. Furthermore, the PDC silicon oxycarbide coatingconstitutes of nanostructured SiO2 domains that can be leached out to enhance SSA to fabricate highly porous oxycarbide derived carbon. Such carbon materials have shownSSA in excess of 916 m2/g with a major part of the porosity being microporous. HRTEM imaging of the hybrids have shown graphene-type carbon layers and clearlyobservable microporosity. Immense prospects lie for the use of these materials in the areas of adsorption, storage and separation of gases (H2, CH4) if the SSA and porositycan be tailored to desired levels.

Polymer Derived SiCO and C-SiCO CeramicsPolymer derived ceramics (PDCs) are a class of multifunctional ceramics synthesizedby the thermal decomposition of the polymeric precursors.

The general formula:

Summary

Ipsita P Swain1, Nishit K Sadual1 and Shantanu K Behera1*

SSA and PSD evaluation of SiCO and SiCO_HF

Before etching

After etching

A.

B.

C-SiCO

C-SiCO_HFSiCO_HF

SiCO

The HF etched SiCO samples were able to retain excellent surface area and produce porosity in the range of 2 nm.The C-SiCO hybrid system with high temperature stability gave a microporous level evolution of porosity and thus an increase in the surface area, whereas the pure SiCO

was not able to. The porosity evolution after HF leaching leads to an increase in the micro pores and thus a huge increase of the surface area. The microscopy shows the presence of the

interconnected graphitic ribbons. The presence of the ultra micro-pores < 1.5 nm in the HF etched NC-SiCO hybrid will lead further to the hydrogen storage applications.

SSA and PSD evaluation of C-SiCO and C-SiCO_HF Morphology evaluation

Micro-meso pores