より効率的な水素生成への新たな道が発見されました

適切な水素触媒を見つける

Hydrogen could, in theory, be a perfect fuel to store energy and power applications that are hard to electrify. This is because it presents a few almost ideal characteristics:

• The byproduct of its combustion is only water
  • And the same can be said when it is used to produce electricity in fuel cells.
• It can burn at very hot temperatures, making it a good alternative to natural gas in metallurgy, chemical processes, etc.
• It only requires water as a resource for its production.
• Hydrogen is itself non-toxic and non-polluting.

しかし、水素ベースの経済の台頭は、コスト効率の良い水素製造が困難であることに阻まれています。これは、ほとんどのグリーン水素（再生可能エネルギーから生成される）が電解によって作られ、現在はプラチナ、ルテニウム、イリジウムなどの高価で希少な触媒に依存しているためです。

したがって、より優れた水素製造方法が存在しない限り、スケールで化石燃料に取って代わることは実現しにくいでしょう。

幸いにも、状況は急速に変化しています。以前、いくつかの可能性について取り上げました。例えば、プラスチック廃棄物を水素に変換する、ニッケルのナノロッドを代替触媒として使用する、または金属部品の製造過程で生じるチタンとニッケルのスクラップ金属 (swarf) を使用する。研究者によって新しい選択肢も追加されています。

最初の研究は、ヨハネス・グーテンベルク大学（ドイツ）やダルムシュタット工科大学（ドイツ）、マックス・プランク高分子研究所（ドイツ）、ハルビン工科大学（中国）、山東大学（中国）の研究者らによる自己最適化触媒¹の創製です。この研究は Angewandte Chemie に掲載され、タイトルは「Self-optimizing Cobalt Tungsten Oxide Electrocatalysts toward Enhanced Oxygen Evolution in Alkaline Media」でした。

二番目の研究は、シンガポールの南洋理工大学、オーストラリアのモナッシュ大学、香港大学（中国）の研究者らが、汚泥をグリーン水素と動物飼料に変換する方法を発明したものです²。この研究は Nature Water に掲載され、タイトルは「Solar-driven sewage sludge electroreforming coupled with biological funnelling to cogenerate green food and hydrogen」でした。

水素触媒の改善

A recurring issue with all hydrogen-producing catalysts is that they degrade over time. This can be due to a deposit forming on the reactive metals, or the metal layer itself slowly degrading and losing components at each catalysis cycle.

This is especially problematic for expensive catalysts of the platinum metals group, but it is also an issue for other types of metal-based catalysts.

So, it is important that the German and Chinese researchers of the first study discussed here have observed self-optimizing behavior with their new catalysts.

“What’s so unique about our catalyst is that it actually enhances its performance over time, while conventional catalysts either maintain their performance at a consistent rate or even lose some of their performance because they are insufficiently durable,”
Dr. Dandan Gao – Johannes Gutenberg University Mainz の研究リーダー

コバルト・タングステン触媒

水素生産のボトルネック解決

The researchers focused on so-called 3d to 5d transition metal oxides, formulated as mixed metal.

These are able to perform a chemical reaction called oxygen evolution reaction (OER), which is half of the reaction occurring during electrolysis of water into hydrogen, in both of the most common electrolyzer designs (AEM and PEM electrolyzers).

 “There are two reactions during the splitting of water. The hydrogen evolution reaction (HER), which produces hydrogen gas, and the oxygen evolution reaction (OER), which produces oxygen gas. The OER represents the bottleneck for the whole reaction. That’s why we are so committed to developing a catalyst that can promote the OER half-reaction.”
Dr. Dandan Gao – Johannes Gutenberg University Mainz の研究リーダー

しかし、これらの新規潜在触媒はまだ十分に理解されておらず、反応中に原子レベルで何が起きているか、あるいは金属がどのような電気化学的形態を取るかについての知識が乏しいです。
この理解不足は、商業的に実用可能な解決策の開発に大きな障壁となっており、触媒を安定した基板に固定する能力も制限しています。

ワンステップ堆積法

The researchers used a copper oxide (L−CuO) microflower substrate with a diameter of 3–5 μm, previously developed in their lab in 2020.

They then used a chemical deposit method to create a layer of cobalt-tungsten alloy at the surface of the copper substrate.

Subsequent analyses revealed the complex microscopic structures of the material, using X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and Raman spectroscopy measurements.

It also confirmed that the catalyst is very firmly tied to the copper substrate.

“The development of viable and scalable deposition approaches is of utmost technological, economic, and ecological significance, enabling stable anchoring of OER pre-catalysts on selected promising substrates with high mechanical integrity”
Source: Angewandte Chemie

自己最適化触媒

From these extremely detailed observations, the scientists discovered that the cobalt ions switch from the Co₂₊ form to the Co3₊. At the same time, the tungsten ions also move from the W5+ to the W6+ forms.

As a result, over time, the electrochemically active part of the catalyst is transferred from the tungsten active site to the cobalt active site.

The catalyst also changes in terms of surface hydrophilicity, or its ability to attract water (the fuel for hydrogen generation): over time, it becomes more hydrophile.

“In general, we recorded notably reduced overpotentials and increased current densities accompanied by a substantial increase in OER kinetics. All this is positive news for the hydrogen production of the future.”
Dr. Dandan Gao – Johannes Gutenberg University Mainz の研究リーダー

This should be a powerful step into making transition metal oxides viable catalysts for hydrogen production.

Not only does this demonstrate that the team of scientists has developed a viable copper substrate for the catalyst, but also that such catalysts can be hyper-stable, and even improve over time.

It also provides the theoretical framework to evaluate the potential of other transition metal combinations not yet as well understood as cobalt-tungsten now is.

触媒は本当に必要か？

都市の汚泥への対処

Meanwhile, hydrogen production could also start to come from the massive waste streams that our cities produce. This is at least the concept explored by Singapore, Chinese, and Australian researchers.

They focused on sewage sludge, a toxic byproduct of cleaning wastewater. These sludges are notoriously difficult to process and dispose of due to their complex structure, composition, and contaminants such as heavy metals and pathogens.

More than 100 million tonnes of sewage sludge are generated globally each year. Common disposal methods – such as incineration or landfill – are time-consuming, energy-inefficient, and contribute to environmental pollution.

Instead, it could become a source of animal feed and hydrogen at the same time.

汚泥を資源に変える

The researchers developed a 3-step process to treat the sludges.

First, they mechanically break down the sludges into a liquid. Then they remove the heavy metals from the organic material through a chemical treatment.

Next, they use an electrochemical process to transform the organic materials into valuable products: acetic acid and hydrogen gas, using specialized electrodes.

Finally, they feed a culture of bacteria able to harness light (cyanobacteria) to turn the leftover organic content into single-cell proteins suitable for animal feed.

Both the second and third steps are either directly (in the case of the bacteria) or indirectly with solar panels (in the case of the electrochemical treatment) powered by sunlight.

This makes the entire sludge recycling process entirely carbon-free, and actually carbon negative as it avoids carbon emissions from the sludge’s normal processing, and replaces other fossil-fuel-based sources for acetic acid, hydrogen, and animal feed.

Hydrogen can be used as a source of clean energy, and acetic acid is a key ingredient for food and pharmaceutical industries.

高効率

This method has been demonstrated to recover 91.4% of the organic carbon in sewage sludge and convert 63% of the organic carbon into single-cell protein.

This is much higher than traditional anaerobic digestion, which typically recovers and converts around 50% of organic materials in sewage sludge.

Overall, this reduces carbon emissions by 99.5% and energy use by 99.3% compared to traditional methods.

“We hope that our proposed method shows the viability of managing waste sustainably and shift how sewage sludge is perceived — from waste to a valuable resource that supports clean energy and sustainable food production.”
Dr Zhao Hu – Nanyang Technological University の研究フェロー

In addition to this high efficiency, it also purifies the sludge from heavy metals, which tend to pollute landfills in the usual methods to deal with it.
This new method indicates that a revolution in how wastewater is dealt with in the world is possible, removing heavy metals (maybe for later recycling?) and producing useful acetic acid, hydrogen, and animal feed all at once.

結論

A hydrogen economy will likely be one with a complex mesh of various hydrogen sources.

Most likely, one will be advanced catalysts performing water electrolysis into hydrogen, without requiring expensive rare metals. It would bring the cost of hydrogen low enough to make it an economically viable competitor to fossil fuels and other green alternatives.

Another likely source is to utilize better the massive millions of tons of waste products created by farming, wastewater, and other human activities. As these need processing anyway, it is by far better that we start processing them in such a way that pollutants (like heavy metals) are removed and new useful products are created.

And if this is done by being solely solar-powered, the better.

タングステン触媒企業

Tungsten is emerging progressively as not only a super resistant metal, used in heavy industry and the defense sector, but also as a power catalyst useful for the chemical industry and to generate hydrogen.

It might even become a powerful high-temperature superconductor when woven in the right molecular configuration.

You can read a technical and investing overview about this resource in “Tungsten – The Secret High-Tech Metal”。

It is also a metal whose supply chain is almost entirely controlled by China, with one exception, Almonty Industries (ALM ).

Almonty Industries

Almonty is a tungsten miner that is currently mostly producing from a mine in Portugal, in operation for the last 125 years.

The company has been working on expanding the Portuguese mine and owns undeveloped deposits in Spain.

The company’s most important project is the ongoing development of a new mine in Sangdong, South Korea. The mine contains more inferred resources than all of its other deposits combined.

As one of the only active and producing tungsten miners in Western countries, Almonty is a key strategic supplier for the defense industry. So, it is an important company for reducing dependence on Chinese supply.

The Sangdong mine’s location makes it a perfect supplier to the defense industry, with South Kore,a new giant in mass production of “low techs” military gear like tanks, artillery, and ammunition (compared to less tungsten-demanding fighter jets, aircraft carriers, etc.).

While China prepares to open a huge tungsten mine in Kazakhstan, Almonty is poised to “substantially shift the politics involved with securing tungsten” when the Almonty Korea Tungsten Project’s Sangdong mine comes online within a few months. When it begins production, it will be one of the world’s largest tungsten mines, accounting for 30% of the non-Chinese supply.
Lewis Black, director, president, and CEO of Almonty Industries

Almonty should start producing tungsten from the Korean mine in early to mid-2025.

Because of its strategic position as essentially the sole large supplier in the West, Almonty was offered a guaranteed price by Plansee. Plansee is a high-performance metal manufacturer and one of Almonty’s larger clients, as well as the owner of 15% of the company.

The minimum guaranteed price was $235/MTU (metric ton unit), with no upper threshold. As Sangdong Mine is aiming for cash costs of $110/mtu, this should virtually ensure a high-profit margin for the project.

With a lucky, almost perfect timing between the upcoming opening of Sangdong and a new trade war between Trump’s America and China, the stock price has reacted strongly and rose by 40% in just 2 days following the announcement of tungsten export restriction from China.

As tungsten becomes more and more important for high-tech applications, as well as geopolitical tensions, stay high, secure, non-Chinese tungsten supply is likely to come to generate a stable premium, with Almonty one of the strongest beneficiaries.

研究参照：

^{1. Christean Nickel et al. (2025)  Self-optimizing Cobalt Tungsten Oxide Electrocatalysts toward Enhanced Oxygen Evolution in Alkaline Media. Angewandte Chemie. 05 2025年2月 https://doi.org/10.1002/anie.202424074} 

 ^{2. Hu Zhao, et al. (2024) Solar-driven sewage sludge electroreforming coupled with biological funnelling to cogenerate green food and hydrogen. Nature Water. Volume 2, pages1102–1115. https://doi.org/10.1038/s44221-024-00329-z}