Professor Mingxin Huang, Chair Professor of Materials Technology and Head of Department of Mechanical Engineering
For a stint after completing his doctoral studies at Delft University of Technology (TU Delft) in the Netherlands, Professor Mingxin Huang worked at the world’s largest steel company in France. In less than two years, he left for an academic position in Hong Kong. It is a decision he never regrets.
Ever since he began his doctoral studies in material science in the late 2000s, Professor Huang has focused on steel, the important material for the industrialised world. Just about seven years after he joined the University of Hong Kong (HKU) in 2010, he unveiled new properties with wide implications for the world.
Applying the novel concept of ‘dislocation engineering’, Professor Huang successfully discovered the Super Steel material, which set two world records in strength-ductility and strength-toughness combinations. The encouraging results were published in Science in 2017 and 2020, respectively.
For long, researchers have grappled with the issue of corrosion in stainless steel amid efforts to create more resilient materials. By using a “sequential dual-passivation” strategy, Professor Huang’s research team developed the novel material - SS-H2 - with superior corrosion resistance. In addition to the single Cr2O3-based passive layer, a secondary Mn-based layer forms on the preceding Cr-based layer at ~720 mV. The sequential dual-passivation mechanism prevents the SS-H2 from corrosion in chloride media to an ultra-high potential of 1700 mV. SS-H2 represents a fundamental breakthrough over conventional stainless steel.
He has applied for patents in multiple countries for his research discoveries, two of which have been granted authorisation. Tons of SS-H2-based wire have been produced in collaboration with a factory from the Mainland.
“Different from the current practice, which mainly focuses on the resistance of natural elements, we specialise in developing high-potential-resistant alloys. Our strategy overcame the fundamental limitation of conventional stainless steel and established a paradigm for alloy development. This breakthrough is exciting and brings new applications,” Professor Huang said.
The novel stainless steel for hydrogen (SS-H2) developed by Professor Huang’s team.
Group support for the major discovery
His ground-breaking discovery was the culmination of persistent work together with his doctoral students and post-doc fellows. It was also the result of a chance discovery, he acknowledged. “One day we did the testing for the steel; then we saw bubbles coming from the water. We did not understand why nor did we expect them,” he recalled. Further tests after the special phenomenon revealed to his team the significance of adding manganese (Mn) as an alloying element. Never had the team anticipated the game-changing effect brought by Mn.
“We used two years to discover the effect of Mn. We studied layers of atoms to try to understand why that was the case, utilising all our background knowledge to discover the new knowledge,” said Professor Huang, who was promoted to Associate Professor with tenure in 2016 and Full Professor in 2019.
Professor Huang (left) and Dr Kaiping Yu (right), the team discovered manganese as a unique alloying element in stainless steel testing experiment.
Addressing the significant cost factor
In contrast to the current practice of using Titanium etc. as structural parts to produce hydrogen from seawater or acid, the new metal found by Professor Huang’s team sharply brings down the cost. “One of the really important barriers today is what we call the catalyst for turning water into hydrogen molecules and oxygen. Usually, very expensive metals are involved. But for the first time we can use super stainless steel to replace them,” he explained.
The discovery provides strong support for global efforts to use hydrogen in place of fossil fuel, and for the goal of Hong Kong and China to reach carbon neutrality in 2050.
In June 2024, the Hong Kong Government announced its Hydrogen Strategy to remove barriers and facilitate the commencement of local hydrogen applications. It is committed to tackling technical challenges in the six major areas of safety, suitable technologies, infrastructure, cost effectiveness, capacity building and public acceptance, as well as the unique situation of Hong Kong.
The Strategy also includes plans to improve legislations, establish standards, align with the market, and create an environment conducive to the development of hydrogen energy in Hong Kong.
Professor Huang’s research achievements have won him numerous accolades. In 2022, he was awarded the prestigious Croucher Senior Research Fellowship and the Xplorer Prize, after receiving the title of Changjiang Scholar Chair Professor, the Gold Medal at the Geneva International Exhibition of Inventions in 2021, and the HKU Outstanding Young Researcher Award in 2018.
Now the Associate Editor of Journal of Materials Science and Technology, and a member of the editorial boards of five academic journals, he has published more than 140 journal papers and is among the top 1% highly cited researchers in his research field by Web of Science.
In 2020, during the pandemic, he put his Super Steel knowledge into use by producing bacteria-resistant spoons, with viral tests conducted by the HKU Faculty of Medicine. Eventually the technology was licensed to a company.
Professor Huang (left) received the Croucher Senior Research Fellowships 2022.
Continuing with advanced research
As a Croucher Fellow, he has proposed a density functional theory (DFT)-guided machine learning (ML) strategy to discover the substitutes for rare-earth elements in ductile magnesium alloys. He hopes to reduce reliance on rare-earth elements, by developing low-cost, strong and ductile magnesium alloys without the addition of rare-earth elements via the DFT-guided ML strategy and dislocation engineering.
Currently working on the prototype for the SS-H2 technology, he is confident about attracting funding support from investors and setting up a start-up company later to make the technology commercially available. It will take time, but Professor Huang remains hopeful of massive adoption of hydrogen as a fuel. “We are moving forward in applying the more economical SS-H2 in hydrogen production from green sources,” he said. “Maybe in one or two years we can turn our invention into a product. I believe if the cost of making hydrogen goes down, then there will be increased incentive by companies to use it as an energy source.”
In particular, it could slash the demand for coal, the key source of carbon emission on the mainland.
“Coal consumption is a major problem in China. There is a need for collaborative research, joint efforts by scientists to make contributions in curbing that. I always believe technological breakthrough is the way to go,” said Professor Huang, who completed his undergraduate and master’s studies at Shanghai Jiao Tong University. “Everyone can make their own contribution in saving our environment. As a researcher, scientist, I have made my own in my field.”
Super Steel has already been included in the Chinese National High School curriculum. While he was in school, chemistry was always Professor Huang’s best subject. That perhaps explains his patience and fascination with the laborious study of chemical reactions.
The prerequisites for a scientist
Good background knowledge in chemistry helps in the field of material science, but it is equally useful to have a strong foundation in other disciplines such as physics or mechanical engineering, he noted. “It is good to have interdisciplinary knowledge. I have learned from my PhD students, the literature they shared during our group discussions, and papers written by others.”
Knowledge aside, he said, good scientists should also have a curious mindset. He recalled that when he was a child, he often raised questions about things around him. Then once at the age of about 10, he discovered after trying to fix a broken wire that combining two dissimilar metals, e.g. aluminum and copper, could result in corrosion.
His time spent in Hong Kong has produced valuable partnerships. As yet another example of interdisciplinary collaboration, his team is developing new denture materials in a joint project with the School of Dentistry.
He is grateful for the rich research opportunities that have come his way over the years. Returning to Asia turned out to be the career choice, after all. “The academic life gives me a lot of freedom. The best thing about being an academic is you can find your own interests. There are two types of research - problem-driven and curiosity-driven. Academics can engage in both.”
An inspiring environment, together with the advanced research facilities on campus, has helped tremendously with his endeavours. “We can see single atoms here at the laboratories at HKU. That is important for discovering new materials. I also used a HK$30 million facility funded by the University Grants Committee at another university, for a project I was a co-principal investigator.”
“The student quality at HKU is very high; we have very good, hardworking PhD students. Supervisors and PhD students work together and learn from each other. It is good to have access to top-notch facilities as a result of increased funding, and investment by the government in science and technology,” said Professor Huang.
Advanced research facilities provided by HKU helped his research flourish.