CO2 Reduction to Formic Acid

ISEF Category: Energy: Sustainable Materials and Design

Subcategory: Triboelectricity and Electrolysis  ·  Difficulty: Advanced  ·  Setup: University Lab  ·  Time: Full Year

The Hook

Carbon dioxide is more than a climate gas. It can also become a feedstock for useful chemicals. That means your cell can act like a tiny factory, not just a battery. The big question is how much of the input current actually becomes formic acid instead of wasted side reactions.

What Is It?

This project looks at electrochemical CO2 reduction, which means using electricity to turn carbon dioxide into a new chemical. In this case, the target product is formic acid, a simple molecule used in industry and in some energy storage research. Think of the setup like a fork in the road. One path makes the product you want, and the other path wastes energy on hydrogen gas or other byproducts.

Faradaic efficiency tells you how much of the electrical charge ends up in the product you are tracking. If you send 100 units of charge into the cell and only 20 units help make formic acid, the Faradaic efficiency is low. That number matters because a reaction can look active and still be inefficient. Your electrolyte, such as KHCO3 made from baking soda, can change pH, conductivity, and CO2 availability, which all affect how the reaction behaves.

Why This Is a Good Topic

This is a strong science fair topic because you can test one clear variable, the electrolyte, and measure a real performance metric, Faradaic efficiency. The project connects to carbon capture, green chemistry, and storage of renewable electricity. You can learn electrochemistry, product analysis, calibration, and error control. A careful student can build a project that looks like real research instead of a simple demo.

Research Questions

• How does electrolyte composition affect the Faradaic efficiency for formic acid formation in a CO2 reduction cell?
• What is the effect of electrolyte concentration on the selectivity for formic acid versus side products?
• Does changing the cation in the bicarbonate electrolyte alter the rate of CO2 conversion?
• To what extent does electrolyte pH change the measured current efficiency for formic acid?
• Which electrolyte condition gives the highest formic acid yield per unit charge passed?
• How does the presence of dissolved CO2 before electrolysis affect product formation?

Basic Materials

• Copper pennies or copper electrodes.
• Zinc-galvanized nails or zinc electrodes.
• Baking soda and distilled water.
• Beakers or clear glass containers.
• DC power supply with adjustable voltage and current readout.
• Carbon dioxide source, such as a safe gas cylinder or controlled carbonation setup.
• pH meter or high-quality pH strips.
• Digital multimeter.
• Analytical balance.
• Graduated cylinders or volumetric glassware.
• Syringes or pipettes for sampling.
• Formic acid test method access, such as school lab titration materials or chromatography setup.
• Safety goggles, nitrile gloves, and lab coat.

Advanced Materials

• Potentiostat or galvanostat.
• Three-electrode electrochemical cell.
• Glassy carbon, copper, or boron-doped diamond working electrode.
• Reference electrode, such as Ag/AgCl.
• Counter electrode, such as platinum mesh or graphite rod.
• Gas-tight electrolysis cell or H-cell.
• High-purity CO2 cylinder with regulator.
• Ion chromatography access.
• HPLC or GC access for product verification.
• NMR access for product confirmation.
• Conductivity meter.
• In-line gas collection setup.
• Deionized water system.

Software & Tools

• Google Sheets: Organizes current, product yield, and Faradaic efficiency calculations.
• Python: Fits trends, graphs results, and helps compare electrolyte conditions with statistics.
• ImageJ: Measures color changes or spot sizes if you use a visual assay for product analysis.
• JASP: Runs t-tests, ANOVA, and simple regression without paid software.
• NIH PubChem: Checks properties, safety notes, and identifiers for formic acid and related compounds.

Experiment Steps

1. Define the exact product you will measure, and choose one analytical method that can confirm formic acid over other soluble products.
2. Select one electrolyte variable to change first, such as bicarbonate concentration, cation type, or pH range.
3. Plan a control cell that keeps the electrode pair, CO2 input, and sampling method the same across trials.
4. Build a calibration curve so your signal can become a real concentration instead of a relative reading.
5. Decide how you will convert product data and charge data into Faradaic efficiency for each trial.
6. Plan a comparison strategy that separates true chemistry effects from noise, drift, and contamination.

Common Pitfalls

• Using a copper penny with unknown plating history, which adds extra metals and changes the reaction surface.
• Letting room air and CO2 contact differ between trials, which changes dissolved gas levels and skews yield.
• Assuming any acidic product signal means formic acid, which can confuse carbonate, acetate, or contamination signals.
• Skipping electrode cleaning and preconditioning, which makes surface state the hidden variable instead of the electrolyte.
• Comparing runs with different total charge passed, which makes Faradaic efficiency numbers hard to interpret.

What Makes This Competitive

A strong version of this project does more than compare two electrolyte mixes. It controls the electrode surface, confirms the product with a real analytical method, and reports Faradaic efficiency with uncertainty. You can make it stand out by testing a sharper question, such as how carbonate chemistry, cation choice, or dissolved CO2 changes selectivity. Careful statistics and clean calibration matter more than flashy hardware.

Project Variations

• Compare KHCO3 with other bicarbonate or carbonate electrolytes to see how buffering changes product selectivity.
• Test different copper surface preparations, such as polished, oxidized, or roughened electrodes, to see how surface state changes formic acid yield.
• Analyze how electrode spacing or cell design changes current efficiency, gas loss, and product formation.

Learn More

• NASA Earth Observatory: Background on carbon cycling and CO2 in the atmosphere, found by searching the NASA Earth Observatory site.
• NIH PubChem: Compound data, safety notes, and identifiers for formic acid, found by searching PubChem.
• USGS Water Science School: Clear explanations of bicarbonate, carbonate, and pH chemistry, found by searching the USGS site.
• MIT OpenCourseWare: Electrochemistry and chemical engineering lecture materials, found by searching MIT OpenCourseWare for electrochemistry courses.
• Journal of The Electrochemical Society: Search review articles and recent papers on CO2 electroreduction and Faradaic efficiency through the journal site or PubMed.