Singapore develops low-cost catalyst to improve efficiency of water splitting to produce hydrogen

According to foreign media reports, a team of scientists from Nanyang Technological University (NTU) in Singapore has discovered a set of parameters that determine the efficiency of low-cost catalyst spinel oxides. This discovery breaks the bottleneck encountered in extracting hydrogen from water using electrolysis (using electricity to decompose water).

(Image source: Nanyang Technological University)

The main challenge of producing hydrogen by electrolysis of water is that energy loss occurs in the chemical reaction of water electrolysis, which increases the cost of water decomposition to produce hydrogen. Therefore, catalysts are needed to accelerate such chemical reactions.

Spinel oxides, typically made from inexpensive transition metals, have attracted interest in recent years as stable, low-cost catalysts. However, efforts to design high-performance spinel oxides have been hampered by a lack of understanding of how they work.

Now, Associate Professor Jason Xu Zhichuan and his team at Nanyang Technological University in Singapore have made two important advances, understanding from an atomic perspective how spinel oxides can accelerate the production of hydrogen in water electrolysis. With this new understanding, the research team used machine learning to select new spinel oxides with enhanced catalytic activity to make water electrolysis more efficient.

Such discoveries also allow the team to further find suitable water splitting methods to produce hydrogen on a large scale. And using renewable energy such as wind or solar power to power, extracting hydrogen from water electrolysis is also a good way to produce hydrogen fuel cells. Hydrogen fuel cells can replace fossil fuels used in power plants, transportation and refueling.

In addition, hydrogen can also replace traditional energy storage devices such as lithium-ion batteries, which gradually lose their power over time.

When water is electrolyzed in an electrolyzer, two main chemical reactions occur: one is the hydrogen production reaction, and the other is the oxygen production reaction, and the two gases are separated by a membrane. Researchers say that the development bottleneck of water electrolysis is mainly the oxygen production reaction, which will lead to the oxygen evolution reaction.

Although the oxygen evolution reaction is very important for decomposing water to produce hydrogen fuel, it is a slow chemical process that reduces the overall energy conversion efficiency, so catalysts such as metal oxides are needed to speed up the reaction. Although precious metal oxides have been proven to be the most advanced catalysts that can reduce energy consumption and improve energy conversion efficiency, their small reserves, high costs, and poor durability limit their large-scale application.

However, spinel oxides are low-cost and abundant, and could be a viable alternative if they are engineered to contain the right parameters, such as the type of transition metal in the spinel oxide to increase its catalytic activity.

Based on the key parameters the team had identified, the team trained a machine learning model with more than 300 spinel oxide datasets to predict the efficiency of any spinel oxide catalyst in seconds. Using this approach, the team found that a new oxide composed of manganese and aluminum was predicted by the model to show superior catalytic activity, which was verified in experiments.