Developing photonic time crystals for visible light has posed significant challenges, primarily because it requires rapid and substantial changes in material properties. However, the research team that previously showcased photonic time crystals at microwave frequencies has presented a groundbreaking strategy for realizing “truly optical” photonic time crystals.
By utilizing theoretical models and electromagnetic simulations, they propose that an array of small silicon spheres could provide the necessary conditions for light amplification, thus making this significant advancement possible in laboratory settings using currently available optical techniques.
“Our work has significantly enhanced the catalyst’s resistance to Cl⁻ corrosion by carefully tuning the electronic environment around cobalt atoms,” said Dr. ZHANG Canhui, first author of the study and a researcher at QIBEBT. “This gives the Co-N/S-HCS both long-term stability and high activity.”
The Co-N/S-HCS electrocatalyst features an asymmetric CoN₃S₁ framework, where each cobalt (Co) atom is bonded to three nitrogen (N) atoms and one sulfur (S) atom. This unique CoN₃S₁ arrangement has been optimized through density functional theory and molecular dynamics simulations, which alters the electronic distribution around the Co atom in comparison to the symmetric CoN4 structure, thus reducing corrosive Cl⁻ adsorption and improving the catalyst’s efficiency in seawater-based electrolytes.
The specially designed CoN₃S₁ configuration not only lessens the harmful effects of Cl- but also enhances the catalyst’s trifunctional capabilities, thereby improving its performance in facilitating essential reactions such as oxygen reduction, oxygen evolution, and hydrogen evolution.
“This multipurpose capability is essential for practical applications in seawater-based energy systems,” said Dr. WANG Xingkun from QIBEBT, one of the study’s corresponding authors.
The researchers further substantiated their design by implementing Co-N/S-HCS in a self-driven seawater-splitting system. When paired with seawater-based Zn-air batteries (S-ZABs) and two-electrode electrolysis devices, the system revealed outstanding performance metrics. The S-ZABs achieved remarkable cycling stability for up to 650 hours, while the two-electrode electrolysis devices sustained stable performance for over 1,100 hours.
More significantly, this integrated system outperformed the CoSA/N, S-HCS configuration, realizing a hydrogen production rate of 469 µmol/h, far exceeding the previous rate of 184 µmol/h. The transformative potential of this work extends beyond the realm of hydrogen production, indicating that Co-N/S-HCS may also serve vital roles in other seawater applications like desalination and cutting-edge energy storage solutions.
“The robustness of Co-N/S-HCS opens up exciting possibilities for sustainable hydrogen production in water-scarce regions, reducing costs and minimizing environmental impact,” said Prof. HUANG Minghua of the Ocean University of China, also a corresponding author of the study.
These results provide a solid basis for the creation of catalysts that can withstand seawater. The research represents a significant advancement in the development of energy solutions that utilize seawater and underscores the possibilities for large-scale sustainable hydrogen generation.
“We hope this work inspires further advancements in sustainable hydrogen production that can meet global energy demands,” said Prof. JIANG Heqing of QIBEBT, another corresponding author.
Journal reference:
- Canhui Zhang, Xu Liu, Cheng Zhen, Hanxu Yao, Liangliang Xu, Haibing Ye, Yue Wang, Xingkun Wang, M. Danny Gu, Minghua Huang, Heqing Jiang. Symmetry-breaking CoN3S1 centers enable inert chloride ion adsorption for facilitating self-driven overall seawater splitting. Chem Catalysis, 2024; DOI: 10.1016/j.checat.2024.101169
