---
title: "Circularity – using hydrogen in the carbon nanofiber production process"
canonical_url: "https://www.smoltek.com/circularity-using-hydrogen-in-the-carbon-nanofiber-production-process/7575/"
date: 2024-06-28
author: "Fredrik Liljeberg"
featured_image: "https://www.smoltek.com/wp-content/uploads/2024/06/sh2-john-schack-top-photo.webp"
categories:
  - name: "News"
    url: "https://www.smoltek.com/category/news.md"
tags:
  - name: "carbon nanofibers"
    url: "https://www.smoltek.com/topic/carbon-nanofibers.md"
  - name: "deeptech"
    url: "https://www.smoltek.com/topic/deeptech.md"
  - name: "electrolyzers"
    url: "https://www.smoltek.com/topic/electrolyzers.md"
  - name: "greenhydrogen"
    url: "https://www.smoltek.com/topic/greenhydrogen.md"
  - name: "hydrogen"
    url: "https://www.smoltek.com/topic/hydrogen.md"
  - name: "nanotechnology"
    url: "https://www.smoltek.com/topic/nanotechnology.md"
---

# Circularity – using hydrogen in the carbon nanofiber production process

The project is now com­ing to its end – with promis­ing results to present. Some main take-aways are:

- The fea­si­bil­i­ty of deposit­ing car­bon nanofibers with a H2-based process has been demon­strat­ed with some chal­lenges remain­ing to make it com­plete­ly viable.
- The main area of improve­ment to tar­get is the growth rate of the CNFs.
- Obser­va­tions of the CNF struc­ture in detail gives an under­stand­ing of how to tack­le the remain­ing challenges.

The growth of CNFs is a fas­ci­nat­ing process and just like the green hydro­gen pro­duc­tion it requires a cat­a­lyst. Each fiber grows from a cat­a­lyst par­ti­cle and usu­al­ly the par­ti­cle can be seen at the tip of the fiber, or at the base. By using a trans­mis­sion elec­tron micro­scope (TEM), capa­ble of cap­tur­ing details on the atom­ic scale, the grown fibers were imaged, and the result was rather unex­pect­ed: The cat­a­lyst par­ti­cle in this case was elon­gat­ed, almost along the whole fiber. The fibers could be called Fe-filled car­bon nan­otubes (CNT) or Fe/​CNT core-shell fibers.

The behav­ior of the cat­a­lyst par­ti­cle is inti­mate­ly cou­pled to the growth and the observed shape is like­ly relat­ed to the issue with low growth rate – lead­ing to plen­ty ideas of how to solve it. For exam­ple, expos­ing the sub­strate to a plas­ma treat­ment before CNF growth starts might loosen the cat­a­lyst par­ti­cle from the sub­strate and change its behav­ior dur­ing growth. This type of core-shell struc­ture is not only a prob­lem to solve how­ev­er, with the fer­ro­mag­net­ic prop­er­ties of the Fe core it could prove inter­est­ing in its own right, per­haps for a future Smoltek busi­ness area? 

In the near-term the pos­si­bil­i­ty of using H2 in the process could lead to new ways of con­trol­ling the car­bon nanofiber struc­ture and increase flex­i­bil­i­ty when it comes to the plan­ning of scale-up and com­mer­cial­iza­tion. One poten­tial up-side with the H2-based process is the pro­duc­tion of free-stand­ing CNFs which could improve water flow and gas bub­ble dis­si­pa­tion in the elec­trol­y­sis cell but whether this can be real­ized with longer fibers remains to be seen.

If you are inter­est­ed, please read more in the full the­sis: [Car­bon nanofibers as cat­a­lyst sup­port – Devel­op­ing an H2-based recipe for plas­ma enhanced chem­i­cal vapor depo­si­tion](https://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=9161661&fileOId=9161679).

![H2 Fecatalyst Transparent](https://www.smoltek.com/wp-content/uploads/2024/06/h2-fecatalyst-transparent.webp)

Fig­ure 1: a) TEM com­pos­ite show­ing CNF grown at gas ratio of 1:40 at 550 C for 15 min­utes. b) High res­o­lu­tion image show­ing graphitic sheets of car­bon on the side of the same CNF. The anno­tat­ed dis­tance is mea­sured between 10 lay­ers yield­ing an inter­lay­er spac­ing of 3.6 Å. c) Ener­gy dis­per­sive x‑ray spec­trum from the same fiber, show­ing the pres­ence of Fe and C. Cu-sig­nal is from the TEM grid that the CNF is trans­ferred to, and there was some Si con­t­a­m­i­na­tion found on the TEM grid which could explain the weak Si-sig­nal observed.

![H2 Cnf Fibers](https://www.smoltek.com/wp-content/uploads/2024/06/h2-cnf-fibers-2.webp)

Fig­ure 2: Free-stand­ing car­bon nanofibers grown using a H2-based recipe. Thus mak­ing CNF-growth almost circular.

*Top pho­to:* Pic­tur­ing a zoomed out view of grown car­bon nanofibers and John Schack, a master’s the­sis stu­dent at Smoltek Hydro­gen, in the lab, reflect­ed in a 6 inch wafer.