State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Physics North Building: Room 361
Yong He is presently a fourth-year Ph.D. candidate engaged in the study of condensed matter physics at Peking University. Following the acquisition of his bachelor’s degree from Inner Mongolia Normal University in 2016, he successfully pursued a master’s degree at the College of Physics and Electronic Information, Inner Mongolia Normal University in 2019 under the guidance of Prof. Min Zhang and Prof. O. Tegus. His research pursuits encompass photocatalysts in lower dimensions, superconductivity (with particular emphasis on few-hydrogen hydrides under ambient pressure), as well as anharmonic effects. He has authored more than 20 peer-reviewed papers published across prestigious scientific journals such as Nano Letters, Small, Advanced Science, Physical Review B, The Journal of Physical Chemistry C, among others. A comprehensive list of his publications can be accessed via ORCID.
In the search for high-temperature superconductivity in hydrides, a plethora of multi-hydrogen superconductors have been theoretically predicted, and some have been synthesized experimentally under ultrahigh pressures of several hundred GPa. However, the impracticality of these high-pressure methods has been a persistent issue. In response, we propose a new approach to achieve high-temperature superconductivity under ambient pressure by implanting hydrogen into lead to create a stable few-hydrogen binary perovskite, Pb4H. This approach diverges from the popular design methodology of multi-hydrogen covalent high critical temperature (Tc) superconductors under ultrahigh pressure. By solving the anisotropic Migdal–Eliashberg equations, we demonstrate that perovskite Pb4H presents a phonon-mediated superconductivity exceeding 46 K with inclusion of spin–orbit coupling, which is six times higher than that of bulk Pb (7.22 K) and comparable to that of MgB2, the highest Tc achieved experimentally at ambient pressure under the Bardeen, Cooper, and Schrieffer framework. The high Tc can be attributed to the strong electron–phonon coupling strength of 2.45, which arises from hydrogen implantation in lead that induces several high-frequency optical phonon modes with a relatively large phonon linewidth resulting from H atom vibration. The metallic-bonding in perovskite Pb4H not only improves the structural stability but also guarantees better ductility than the widely investigated multi-hydrogen, iron-based and cuprate superconductors. These results suggest that there is potential for the exploration of new high-temperature superconductors under ambient pressure and may reignite interest in their experimental synthesis in the near future.
2023
Few-Hydrogen High-Tc Superconductivity in (Be4)2H Nanosuperlattice with Promising Ductility under Ambient Pressure
The multi-hydrogen lanthanum hydride LaH10 is well recognized as having the highest critical temperature (Tc) of 250–260 K under unrealistically ultrahigh pressures of about 170–200 GPa. Here, we propose a novel idea for designing a new ambient-pressure high-Tc superconductor by inserting a hexagonal H-monolayer into two close-packed Be monolayers to form a new and stable few-hydrogen metal-bonded layered beryllium hydride (Be4)2H nanosuperlattice, with better ductility than multi-hydrogen, cuprate, and iron-based superconductors, completely contrary to the conventional design strategy for multi-hydrogen covalent high-Tc superconductors with poor ductility at several hundred GPa. We find that (Be4)2H is a phonon-mediated Eliashberg superconductor with a large electron–phonon coupling constant of 1.41 and a high Tc of 84–72 K with Coulomb repulsion pseudopotential μ* = 0.07–0.13. Importantly, (Be4)2H is the only new high-Tc superconductor and fills the gap in the absence of ambient-pressure superconductors around the liquid-nitrogen temperature with good ductility, which is highly beneficial for practical applications.
Phonon-mediated superconductivity in the metal-bonded perovskite Al4H up to 54 K under ambient pressure
Multi-hydrogen lanthanum hydrides have shown the highest critical temperature Tc at 250-260 K under 170-200 GPa. However, such high pressure is a great challenge for sample preparation and practical application. To address this challenge, we propose a novel design strategy for ambient-pressure superconductors by constructing new few-hydrogen metal-bonded perovskite hydrides, such as Al-based superconductor Al4H, with better ductility than the well-known multi-hydrogen, cuprate and Fe-based superconductors. Based on the Migdal-Eliashberg theory, we predict that the structurally stable Al4H has a favorable Tc of up to 54 K under atmospheric pressure.
Enhancement for phonon-mediated superconductivity up to 37 K in few-hydrogen metal-bonded layered magnesium hydride under atmospheric pressure
YongHe, Juan Du*, Shi-ming Liu, Chong Tian, Min Zhang, Yao-hui Zhu, Hongxia Zhong, Xinqiang Wang, and Jun-jie Shi*
The discovery of superconductivity in layered MgB2 has renewed interest in the search for high-temperature conventional superconductors, leading to the synthesis of numerous hydrogen-dominated materials with high critical temperatures (Tc) under high pressures. However, achieving a high-Tc superconductor under ambient pressure remains a challenging goal. In this study, we propose a novel approach to realize a high-temperature superconductor under ambient pressure by introducing a hexagonal H monolayer into the hexagonal close-packed magnesium lattice, resulting in a new and stable few-hydrogen metal-bonded layered magnesium hydride (Mg4)2H1. This compound exhibits superior ductility compared to multi-hydrogen, cuprate, and iron-based superconductors due to its metallic bonding. Our unconventional strategy diverges from the conventional design principles used in hydrogen-dominated covalent high-temperature superconductors. Using anisotropic Migdal–Eliashberg equations, we demonstrate that the stable (Mg4)2H1 compound is a typical phonon-mediated superconductor, characterized by strong electron–phonon coupling and an excellent Tc of 37 K under ambient conditions, comparable to that of MgB2. Our findings not only present a new pathway for exploring high-temperature superconductors but also provide valuable insights for future experimental synthesis endeavors.
2022
High hydrogen production in the InSe/MoSi2N4 van der Waals heterostructure for overall water splitting
YongHe, Yao-hui Zhu*, Min Zhang*, Juan Du, Wen-hui Guo, Shi-ming Liu, Chong Tian, Hong-xia Zhong, Xinqiang Wang, and Jun-jie Shi*
Very recently, the septuple-atomic-layer MoSi2N4 has been successfully synthesized by a chemical vapor deposition method. However, pristine MoSi2N4 exhibits some shortcomings, including poor visible-light harvesting capability and a low separation rate of photo-excited electron–hole pairs, when it is applied in water splitting to produce hydrogen. Fortunately, we find that MoSi2N4 can be considered as a good co-catalyst to be stacked with InSe forming an efficient heterostructure photocatalyst. Here, the electronic and photocatalytic properties of the two-dimensional (2D) InSe/MoSi2N4 heterostructure have been systematically investigated by density functional theory for the first time. The results demonstrate that 2D InSe/MoSi2N4 has a type-II band alignment with a favourable direct bandgap of 1.61 eV and exhibits suitable band edge positions for overall water splitting. Particularly, 2D InSe/MoSi2N4 has high electron mobility (104 cm2 V−1 s−1) and shows a noticeable optical absorption coefficient (105 cm−1) in the visible-light region of the solar spectrum. These brilliant properties declare that 2D InSe/MoSi2N4 is a potential photocatalyst for overall water splitting.
2019
Improvement of Visible-Light Photocatalytic Efficiency in a Novel InSe/Zr2CO2 Heterostructure for Overall Water Splitting
YongHe, Min Zhang*, Jun-jie Shi*, Yu-lang Cen, and Meng Wu
The unexpected visible-light absorption, low recombination of electron–hole pairs, and high carrier mobility are found in a novel two-dimensional (2D) InSe/Zr2CO2 van der Waals heterostructure for overall water splitting photocatalysis. The photocatalytic mechanism has been systematically investigated using first-principles calculations for the first time. We prove that the 2D InSe/Zr2CO2 heterostructure is a robust and promising visible-light photocatalyst with several distinct advantages, as follows. It has a direct band gap of 1.81 eV, which is a more favorable band gap for visible-light photocatalysis. Its type-II band alignment directly leads to a significant electron–hole separation with electrons (holes) localized in the InSe (Zr2CO2) monolayer. The indirect band gap of the InSe (Zr2CO2) monolayer further suppresses the electron–hole recombination in it. Naturally, the recombination of the photogenerated electrons and holes is greatly suppressed in the InSe/Zr2CO2 heterostructure, which improves the solar energy utilization effectively. Moreover, a large optical absorption coefficient (105 cm–1) has been confirmed in the 2D InSe/Zr2CO2 heterostructure with the electron (hole) mobility reaching up to 104 (103) cm2 V–1 s–1, which is highly beneficial and desirable for enhancing its photocatalytic efficiency.
2018
Two-dimensional g-C3N4/InSe heterostructure as a novel visible-light photocatalyst for overall water splitting: a first-principles study
YongHe, Min Zhang*, Jun-Jie Shi*, Yao-Hui Zhu, Yu-Lang Cen, Meng Wu, Wen-Hui Guo, and Yi-Min Ding
The enhanced visible-light harvesting, low recombination of electron–hole pairs and high carrier mobility are found in a novel g-C3N4/InSe hybrid two-dimensional (2D) heterostructure photocatalyst by using first-principles calculations for the first time. The photocatalytic mechanism of g-C3N4/InSe is comprehensively investigated. Our calculations show that 2D g-C3N4/InSe heterostructure has a direct band gap of 1.93 eV and a typical type-II band alignment with holes and electrons located in metal-free g-C3N4 monolayer and non-noble metal InSe nanosheet, respectively. A remarkable visible-light absorption can thus be expected. The electrons and holes located in InSe and g-C3N4 monolayers have a high mobility (104 and 102 cm2 V–1 s–1), which is beneficial for improving the catalytic efficiency. The charge density difference and type-II band structure indicate that the photo-generated electrons easily transfer from g-C3N4 monolayer to InSe nanosheet, and the holes are transferred from InSe to g-C3N4, reducing the electron–hole recombination. Compared with the well-known 2D g-C3N4/MoS2 hybrid photocatalyst composed of g-C3N4 nanosheet and MoS2 monolayer with a low electron mobility (< 200 cm2 V–1 s–1) and fast electron–hole recombination due to its direct bandgap, g-C3N4/InSe heterostructure photocatalyst has a distinctive advantage in improving the photocatalytic hydrogen evolution performance due to the high carrier mobility and suppressing the recombination of photo-generated electrons and holes by the indirect band gap of InSe monolayer. These clearly prove that g-C3N4/InSe is an energetic photocatalyst for overall water splitting under visible-light irradiation.
Please contact me via email at hey@stu.pku.edu.cn or Hey_PhD@icloud.com.