A research team led by Professor Jin Mingshang of the Frontier Institute of Science and Technology and the State Key Laboratory of Multiphase Flow in Power Engineering at the Xi'an Jiaotong University (XJTU) has made significant progress in the regulation of the surface strain of catalysts to improve the catalytic performance of platinum (Pt).

Their research "Mastering the surface strain of Pt catalysts for efficient electrocatalysis" was published in the scientific journal Nature on Oct 6.

The research results can not only fundamentally explore how strain affects platinum electrocatalysis, but also provide a promising way to manufacture high-performance platinum catalysts for renewable energy conversion reactions.

Jin's team discovered in the early stage that palladium (Pd) nanocrystals can achieve continuous volume changes through phosphating and dephosphorizing reactions, and developed a new strain adjustment method platinum-based core-shell structure based phosphating and dephosphorizing treatments.

This method can be applied to adjust the surface strain of platinum catalysts with different surface structures, and is even expected to be further extended to other materials, with universal applicability.

Using the volume expansion and contraction of the palladium-based nanocube core during the phosphating/dephosphating process to control the lattice strain of the platinum shell

In order to achieve precise and continuous adjustment of the lattice strain of the platinum catalyst, the team first deposited platinum on the surface of a palladium-based material to form Pd@Pt and PdP@Pt core-shell structures.

In previous research, Jin's team found that using a phosphating treatment of palladium nanocubes would cause significant volume expansion. On the contrary, the dephosphorization treatment can also shrink the volume of PdP nanoparticles to their original state.

Based on this, the study found that phosphating (dephosphorizing) Pd@Pt (PdP@Pt core-shell structure) can obtain the corresponding tensile (compressive) strain. The team further achieved precise adjustment of the degree of platinum lattice expansion by controlling the degree of phosphating (dephosphating), and obtained a continuously adjustable lattice strain in the range of -5.1% to 5.9%.

The effect of experimental conditions on the lattice strain was analyzed through an atomic-resolved spherical aberration electron microscopy characterization system. Combined with theoretical calculations, it was revealed that the lattice strain energy changes the adsorption strength and adsorption sites of the key species in the catalytic system on the surface of the platinum catalyst, thereby affecting its catalytic activity.

More importantly, based on an in-depth understanding of the "strain-activity" structure-activity relationship of platinum catalysts, the team used strain optimization to increase the activity of platinum catalysts in methanol electrocatalytic oxidation and hydrogen evolution reactions by 2.5 times and 1.5 times, respectively.

The development of lattice strain adjustment methods provides detailed theoretical guidance and brand-new experimental methods for the design and preparation of high-efficiency platinum catalysts, and is expected to be applied to fuel cells, electrolysis of water, hydrogen and oxygen, and other fields to support China's national energy strategy.

Led by Jin, the strain adjustment experiment and catalytic performance characterization were mainly completed by Dr. He Tianou and postdoctoral researcher Wang Weicong on his team. 

Spherical aberration electron microscopy characterization and strain analysis were completed by Dr. Shi Fenglei from Shanghai Jiao Tong University, while the theoretical calculation was completed by Dr. Yang Xiaolong from Chongqing University.

Dr. Li Xiang from Xi'an Technological University participated in part of the research and results analysis and discussion.

The XJTU State Key Laboratory of Multiphase Flow in Power Engineering was the first unit and communication unit. The project was funded by the National Natural Science Foundation of China.

Platinum catalysts are currently the most important type of catalysts in the energy field, and have been widely used in sustainable energy systems such as fuel cells and hydrogen production by water splitting.

At present, the adjustment of the surface strain of the catalyst mainly relies on the deposition of platinum on the surface of another material (the formation of a core-shell structure).

How to achieve precise and continuous regulation of the surface strain of platinum catalysts is a challenging problem that has attracted much attention and urgently needs to be solved in the field of catalysis.

Link to the paper: https://www.nature.com/articles/s41586-021-03870-z

More about Jin:

Jin is a professor and an academic supervisor for PhD students at XJTU. He became a staff member of the XJTU Frontier Institute of Science and Technology in March 2012 and joined the State Key Laboratory of Multiphase Flow in Power Engineering in 2016.

Jin was selected for the XJTU Plan for the Cultivation of Young Leading Talents in 2016, Shaanxi Provincial Plan for the Cultivation of Young Leading Talents in Universities in 2018, and the 2020 Elsevier Annual List of Highly Cited Chinese Researchers in 2021.

Jin has published over 60 research papers in major international journals such as Nature, Angew. Chem. Int. Ed. and Nat. Commun. Eight of them have been on the list of SCI highly cited papers and have been cited over 7,000 times in total.

Jin has been invited by the International Union of Materials Research Societies and the Chinese Chemical Society to present his reports five times. He has been in charge of four research projects associated with the National Natural Science Foundation of China, and possesses three specific Chinese invention patents and a US patent.