Synthesis of nanostructured graphitic carbons by iron-catalyzed graphitization of biomass

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Hunter, Robert Duncan ORCID: https://orcid.org/0000-0001-9344-4943 (2023). Synthesis of nanostructured graphitic carbons by iron-catalyzed graphitization of biomass. University of Birmingham. Ph.D.

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Abstract

Porous carbon materials have a wide range of applications, finding use as anode materials for batteries, electrocatalyst supports, supercapacitors and adsorbents for water treatment. High performance in these applications is achieved through features such as high thermal and electrical conductivity and high surface area. Therefore, considerable effort has gone into developing simple and scalable means of producing carbon materials with precise porosity as well as tailored bulk and surface structure.

Porous carbons with a high graphitic content are particularly attractive due to their high chemical stability and electronic conductivity, and a good route to make these materials is through catalytic graphitization. Here, organic precursors are combined with a metal compound, often iron, before heating in an inert atmosphere to produce iron-based nanoparticles in situ, which catalyze the conversion of amorphous carbon to graphitic nanostructures.

Throughout the literature, organic precursors vary widely and depending on the precursors and reaction conditions, catalytic graphitization has produced various graphitic nanostructures, however, the underlying reasons as to why some structures are preferred over others is not known. In this thesis, a systematic study of the effect of organic precursor structure is explored as a means of controlling the catalyst particle size, which has a direct effect on the porosity of the material. This study is extended to investigate a selection of nitrogen-containing, biomass-derived organic precursors and the presence of nitrogen was found to have an inhibiting effect on the iron-catalyzed graphitization process.

The precise chemical and physical nature of the catalytic species in iron-catalyzed graphitization systems is also an area of dispute. To address this, iron-catalyzed graphitization is studied in situ on both the bulk and nano-scale, using experimental techniques such as synchrotron X-ray diffraction and environmental transmission electron microscopy, in combination with molecular dynamics simulations to probe the underlying mechanism of graphitization.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):