A team of researchers at the Korea Advanced Institute of Science and Technology (KAIST) has discovered a novel technique to enhance the efficiency of iron- and nitrogen-doped carbon electrodes in hydrogen fuel cells. These electrodes are notably far more cost-effective, estimated to be 1,000 times cheaper, compared to the currently employed platinum catalysts.
Platinum plays a pivotal role in accelerating the oxygen reduction reaction at the cathode within hydrogen fuel cells. This not only heightens performance but also curtails the creation of intermediate substances like hydrogen peroxide, which can lead to equipment degradation over time.
An article published in the peer-reviewed journal ACS Catalysis reveals that the KAIST researchers determined that oxygen binding occurs on iron- and nitrogen-doped carbon (Fe-N-C) electrodes, obstructing the final step of intermediary desorption. However, through the treatment of these electrodes with phosphine gas, a FeN3PO moiety forms within the molecule, thereby expediting the oxygen reduction reaction sans the production of intermediaries. This approach resulted in a yield of less than 5% when evaluated for peroxide production.
This methodology was verified in the laboratory using small-scale proton exchange membrane (PEM) and anion exchange membrane (AEM) fuel cells featuring phosphine-treated Fe-N-C electrodes. The researchers characterize the outcome as “among the most impressive performances compared to previously documented heteroatom-doped Fe−N−C catalysts.” Nonetheless, in terms of practical cell voltage and power density, platinum electrodes still generally surpassed phosphine-treated Fe-N-C. Consequently, if this technology were to be commercialized, there might be a need to balance cost and performance considerations.
Interestingly, the distinction in performance between the two materials was narrower for AEM than PEM fuel cells, with the experimental electrode even surpassing the precious metal at higher current densities.
In the context of PEM electrolyzers, platinum is utilized in relatively small quantities, causing a mere 0.1% escalation in equipment expenses for every 10% surge in the metal’s price. However, the situation differs for PEM and AEM fuel cells, where platinum is a pivotal component and contributes significantly to the cost. Approximately one-third of the total cost of a PEM fuel cell is attributed to platinum, according to data from the US Department of Energy and the European Commission.
What exactly is a Hydrogen Car?
A hydrogen fuel-cell vehicle (often abbreviated as HFCV) employs the same type of electric motor as a battery-electric car to propel itself. However, instead of relying on a hefty and substantial battery, it draws power from a fuel-cell stack. Within this stack, pure hydrogen (H2) flows through a membrane, uniting with oxygen (O2) sourced from the atmosphere. This chemical reaction generates the electricity required to set the wheels in motion, along with producing water vapor as a byproduct. Technically speaking, this design categorizes a fuel-cell vehicle as a series hybrid, and that’s why it’s sometimes referred to as a fuel-cell hybrid electric vehicle (FCHEV).
From a scientific perspective, hydrogen isn’t regarded as a fuel; rather, it’s considered an energy carrier. However, for practical purposes, this distinction is often overlooked. HFCV owners refuel their vehicles at “hydrogen fueling stations,” which bear a striking resemblance in concept to traditional gasoline stations and offer a similarly swift five-minute refueling experience.
You might have heard that hydrogen is the most abundant element in the universe. While this is true at the atomic level, hydrogen is never found in its pure form; it’s invariably bonded with other elements. Its strong affinity to combine with various elements makes it an excellent carrier of energy.
Producing pure hydrogen for vehicles involves an energy-intensive process called “cracking,” which typically converts compounds like natural gas (CH4) into pure H2, with carbon dioxide (CO2) as a byproduct. (Currently, a significant portion of hydrogen production comes from fossil fuels like natural gas.) However, when this hydrogen flows through a fuel cell, it promptly returns the stored energy, converting it into electricity as it combines with oxygen. As a result, the vehicle’s exhaust emits nothing more than water vapor (H2O).