An international team led by City University of Hong Kong (CityU) has announced a groundbreaking step forward that has added significantly to the technical know-how required to clean up the planet.

The discovery, published in one of the world’s premier science journals, Nature, centers on developing a highly efficient electrocatalyst that can enhance H₂ generation through electrocatalytic water splitting.

Titled “Phase-dependent growth of Pt on MoS2 for highly efficient H₂ evolution”, the paper was published on September 13 in London. Cleaner energy sources are desperately needed, but the challenges in weaning the world off fossil fuels and onto more sustainable energies are enormous.

“H₂ generated by electrocatalytic water splitting is regarded as one of the most promising clean energies for replacing fossil fuels in the near future, reducing environmental pollution and the greenhouse effect,” said Professor Zhang Hua, Herman Hu Chair Professor of Nanomaterials at CityU, who is spearheading the research.

Professor Zhang’s collaborators include Professor Anthony R. J. Kucernak from the Department of Chemistry at Imperial College London and researchers from universities and research institutes in Hong Kong, mainland China, Singapore and the UK.

The critical development in the CityU-led research is establishing novel catalysts by using the transition-metal dichalcogenide (TMD) nanosheets as supports, enabling superior efficiency and high stability during the electrocatalytic H₂ evolution reaction (HER), a vital step in electrocatalytic water-splitting, also known as the water electrolysis technique, for H₂ production.

The team has been exploring how to enhance the performance of the HER process by engineering the crystal phase of nanomaterials for several years. Although TMD nanosheets with unconventional crystal phases possess great potential to be used as catalyst supports, fabricating such sheets pure enough for HER is far from straightforward.

But in this research, Professor Zhang’s team has developed a new method to prepare unconventional-phase TMD nanosheets with high phase-purity and quality. Furthermore, they have investigated the crystal phase-dependent growth of noble metals on the TMD nanosheet supports.

Technically speaking, they found that the 2H-phase template facilitates the epitaxial growth of Pt nanoparticles, whereas the 1T′-phase template supports single-atomically dispersed Pt atoms (s-Pt). The synthesized s-Pt/1T′-MoS2 serves as a highly efficient catalyst for HER and can work for 500 hours in the water electrolyzer, demonstrating that 1T′-TMD nanosheets could be effective supports for catalysts.

“We will develop more efficient catalysts based on this finding and explore their applications in various catalytic reactions,” said Dr Shi Zhenyu, a postdoctoral researcher in CityU’s Department of Chemistry and the first author of the paper.

These findings expand the scope of phase engineering in nanomaterials, paving the way for the design and synthesis of highly efficient catalysts, contributing to cleaner energies and more sustainable development.