# Hummers method: graphite to GO to rGO

> Graphite is oxidized in concentrated sulfuric acid with sodium nitrate and potassium permanganate, diluted with water, treated with hydrogen peroxide and sonicated into graphene oxide (GO) sheets. Reducing the GO, for example with hydrazine hydrate or sodium borohydride, removes most of the oxygen groups and gives reduced graphene oxide (rGO).

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- Updated: 2026-10-14
- Category: Graphene synthesis
- Method: Hummers method, top-down
- Starting materials: Flake graphite
- Product: Graphene oxide (stage I), then reduced graphene oxide (stage II)
- Typical size: Single-layer GO sheets; their lateral size follows the starting graphite
- Key result: GO: heavily oxidized and insulating. rGO: sp² network partly restored; defects and some oxygen remain
- Scalability: High: batch wet chemistry from cheap graphite
- Figure: 1920 × 1080 px, 72 editable layers (13 generated objects with settings)

## Steps

1. **I · Acid and oxidants**: 100 g graphite and 50 g NaNO₃ in 2.3 L H₂SO₄; 300 g KMnO₄ added while the mixture stays below 20 °C (Hummers & Offeman)
2. **I · Oxidation**: Held at about 35 °C, then diluted with water, which brings it to about 98 °C
3. **I · Work-up and exfoliation**: H₂O₂ removes the leftover permanganate; after washing, ultrasonication in water splits the graphite oxide into GO sheets
4. **II · Reduction**: GO in water is reduced with hydrazine hydrate (Stankovich et al.) or sodium borohydride (Shin et al.); the reduced sheets aggregate
5. **II · Work-up**: Filter, wash and dry the rGO

## Strengths

- Cheap starting material, scalable batch chemistry
- GO disperses in water, so it is easy to process into films and composites
- Reduction restores much of the conductivity; NaBH₄ gives lower sheet resistance than hydrazine

## Limitations

- NaNO₃ releases toxic NOₓ; strong oxidants and acid need care
- rGO keeps defects and residual oxygen, unlike pristine graphene
- Hydrazine is toxic, and the reduced sheets aggregate in water

## Uses

- Conductive films, inks and coatings
- Battery and supercapacitor electrodes
- Composites, membranes and sensors

## References

1. Hummers & Offeman, “Preparation of graphitic oxide”, J. Am. Chem. Soc. 1958. https://doi.org/10.1021/ja01539a017 (method origin)
2. Stankovich et al., “Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide”, Carbon 2007. https://doi.org/10.1016/j.carbon.2007.02.034 (primary)
3. Shin et al., “Efficient reduction of graphite oxide by sodium borohydride and its effect on electrical conductance”, Adv. Funct. Mater. 2009. https://doi.org/10.1002/adfm.200900167 (primary)
4. Marcano et al., “Improved synthesis of graphene oxide”, ACS Nano 2010. https://doi.org/10.1021/nn1006368 (further reading)
5. Li et al., “Processable aqueous dispersions of graphene nanosheets”, Nat. Nanotechnol. 2008. https://doi.org/10.1038/nnano.2007.451 (further reading)

Credit: Redrawn and simplified after Hummers & Offeman, J. Am. Chem. Soc. 1958 (doi:10.1021/ja01539a017); reduction after Stankovich et al., Carbon 2007 (doi:10.1016/j.carbon.2007.02.034) and Shin et al., Adv. Funct. Mater. 2009 (doi:10.1002/adfm.200900167).

## Questions

**What does the “Hummers method: graphite to GO to rGO” template show?** Graphite is oxidized in concentrated sulfuric acid with sodium nitrate and potassium permanganate, diluted with water, treated with hydrogen peroxide and sonicated into graphene oxide (GO) sheets. Reducing the GO, for example with hydrazine hydrate or sodium borohydride, removes most of the oxygen groups and gives reduced graphene oxide (rGO).

**What are the steps shown in “Hummers method: graphite to GO to rGO”?** 1. I · Acid and oxidants: 100 g graphite and 50 g NaNO₃ in 2.3 L H₂SO₄; 300 g KMnO₄ added while the mixture stays below 20 °C (Hummers & Offeman). 2. I · Oxidation: Held at about 35 °C, then diluted with water, which brings it to about 98 °C. 3. I · Work-up and exfoliation: H₂O₂ removes the leftover permanganate; after washing, ultrasonication in water splits the graphite oxide into GO sheets. 4. II · Reduction: GO in water is reduced with hydrazine hydrate (Stankovich et al.) or sodium borohydride (Shin et al.); the reduced sheets aggregate. 5. II · Work-up: Filter, wash and dry the rGO.

**What are the starting materials and the product?** Starting materials: Flake graphite. Product: Graphene oxide (stage I), then reduced graphene oxide (stage II).

**Which papers is “Hummers method: graphite to GO to rGO” based on?** Hummers & Offeman, “Preparation of graphitic oxide”, J. Am. Chem. Soc. 1958 (doi:10.1021/ja01539a017); Stankovich et al., “Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide”, Carbon 2007 (doi:10.1016/j.carbon.2007.02.034); Shin et al., “Efficient reduction of graphite oxide by sodium borohydride and its effect on electrical conductance”, Adv. Funct. Mater. 2009 (doi:10.1002/adfm.200900167); Marcano et al., “Improved synthesis of graphene oxide”, ACS Nano 2010 (doi:10.1021/nn1006368); Li et al., “Processable aqueous dispersions of graphene nanosheets”, Nat. Nanotechnol. 2008 (doi:10.1038/nnano.2007.451).

**Can I edit the “Hummers method: graphite to GO to rGO” template?** Yes. Open it in the LabCanvas editor: all 72 layers are editable, including 13 generated objects (structures, plots, equipment) with their own settings. Change the text, colours and layout, then export PNG, TIFF, SVG or PDF.

**Do I need an account to use this template?** Not to view it here. To open and edit it, sign in to LabCanvas or create a free account (the free plan keeps one design of each kind). Downloading the figure is part of LabCanvas Pro (US$19 a month or US$199 a year).