Hydrogen is a clean and renewable energy source that can be used for various applications, such as fuel cells, vehicles, and power generation. However, producing hydrogen from water requires a lot of electricity and a catalyst to accelerate the reaction that splits water into hydrogen and oxygen.
Currently, most of the catalysts used for this process are based on precious metals, such as platinum and ruthenium, which are expensive and scarce. Therefore, finding a cheaper and more efficient alternative is crucial for the development of a sustainable hydrogen economy.
NiFeMo-P-C: A Carbon-Based Catalyst with High Activity and Stability
One of the challenges in developing catalysts for water splitting is to balance the activity and stability of the material. Activity refers to how fast the catalyst can facilitate the reaction, while stability refers to how long the catalyst can maintain its performance without degradation.
A research team from China has recently reported a new carbon-based catalyst that has both high activity and stability for water splitting. The catalyst is composed of a carbon compound containing nickel, iron, molybdenum, and phosphorus (NiFeMo-P-C), which is anchored on a nickel foam substrate.
The researchers found that this catalyst can reduce the electricity required to split water by 30% compared to platinum-based catalysts. Moreover, the catalyst can retain its activity for over 100 hours without significant loss.
The researchers attributed the high performance of this catalyst to its unique structure and composition. The carbon compound forms nanosheets with abundant active sites on the surface, while the nickel foam provides a conductive and porous support for efficient electron and mass transfer. The addition of iron, molybdenum, and phosphorus enhances the catalytic activity and stability by creating synergistic effects among the elements.
The researchers also demonstrated that this catalyst can be used to produce hydrogen from seawater, which is more abundant and accessible than freshwater. This could expand the potential applications of this technology for coastal regions and islands.
Ni2+/Co2+ Doped Au-Fe7S8: A Two-Dimensional Catalyst with Exceptional Activity
Another challenge in developing catalysts for water splitting is to optimize the performance of both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which are the two steps involved in splitting water. Usually, different catalysts are needed for each step, which increases the cost and complexity of the system.
A research team from Australia has recently discovered a new two-dimensional catalyst that can perform both HER and OER with exceptional activity. The catalyst is made of gold-iron sulfide nanocrystals (Au-Fe7S8) doped with small amounts of nickel and cobalt ions (Ni2+/Co2+).
The researchers found that this catalyst can achieve a current density of 10 mA/cm2 at an overpotential of only 270 mV for OER, which is much lower than the current benchmark material, ruthenium oxide (RuO2), which requires 350 mV. For HER, the catalyst can achieve a current density of 10 mA/cm2 at an overpotential of only 60 mV, which is comparable to platinum-based catalysts.
The researchers explained that the doping of Ni2+/Co2+ ions transforms the poor-performing Au-Fe7S8 into a viable and efficient catalyst by creating more active sites and improving the charge transfer kinetics. The two-dimensional structure of the nanocrystals also provides a large surface area and facilitates the exposure of active sites.
The researchers claimed that this discovery could be a game changer for green hydrogen production, as it offers a cheaper and more efficient alternative to precious metal-based catalysts. They also said that this finding opens new avenues for future research in the energy sector, putting Australia at the forefront of renewable and clean energy research and applications.
Conclusion
Hydrogen production from water is a promising technology for generating clean and renewable energy. However, it requires a lot of electricity and a catalyst to accelerate the reaction. Finding a cheaper and more efficient catalyst is therefore essential for advancing this technology.
In this article, we introduced two recent breakthroughs in hydrogen production catalysts: NiFeMo-P-C, a carbon-based catalyst with high activity and stability; and Ni2+/Co2+ doped Au-Fe7S8, a two-dimensional catalyst with exceptional activity for both HER and OER. These catalysts could be game changers for the future of green energy, as they offer a cost-effective and sustainable alternative to precious metal-based catalysts.
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