Just now, the top ten scientific advances in China in 2022 were announced

◎ Science and Technology Daily reporter Liu Yin

On March 17, the High Technology Research and Development Center (Basic Research Management Center) of the Ministry of Science and Technology released the top ten scientific advances in China in 2022. Ten major scientific advances, including the Zhurong patrol radar revealing the shallow layered structure of the Utopia Plain on Mars and the new principle of direct electrolysis of seawater to produce hydrogen, stood out from 30 candidate advances.

According to the number of votes, the top ten scientific advances in China in 2022 are:

Zhurong's patrol radar reveals the shallow layered structure of Mars' Utopia Planitia

FAST details active repeating fast radio bursts

A new principle for direct hydrogen production from seawater electrolysis

Revealing the mutation characteristics and immune escape mechanism of the new coronavirus

Achieving high-efficiency all-perovskite tandem solar cells and modules

New principle switching device provides new solution for high-performance mass storage

Achieving quantum coherent synthesis of ultracold triatomic molecules

Ethylene glycol synthesis under mild pressure conditions

Discovery of a new mechanism for femtosecond laser-induced micro-nanostructuring of complex systems

Experiment confirms superconducting state "segmented Fermi surface"

1

Zhurong's patrol radar reveals the shallow layered structure of Mars' Utopia Planitia

Detailed information on the underground structure and physical properties of Mars is the key to studying the evolution of Martian geology and its habitability, and is one of the important contents of Mars exploration.

Chen Ling, Zhang Jinhai and other teams from the Institute of Geology and Geophysics of the Chinese Academy of Sciences conducted in-depth analysis and fine imaging of the low-frequency radar data of the Zhurong Mars rover, which traveled for about 4 months and detected up to 1,171 meters. They obtained high-precision structural layered images and stratigraphic physical property information above 80 meters above the shallow surface in the southern part of Utopia Planitia. The study found that there are two sets of sedimentary sequences that taper upward under the several-meter-thick pyrosol layer in this area: the first set of sequences is located about 10 to 30 meters underground, and its formation may be related to short-term floods, long-term weathering or repeated meteorite impacts about 1.6 billion years ago; the second set of sequences is located about 30 to 80 meters underground, which may be deposited by a large flood event 3.5 to 3.2 billion years ago. No evidence of liquid water has been found above 80 meters in this area, but the possibility of salt ice cannot be ruled out.

This study reveals the fine structure and physical properties of the current Martian surface, provides observational evidence of long-term water activity on Mars, and provides an important basis for a deeper understanding of the geological evolution, environment, and climate change of Mars.

A selfie taken by the Zhurong Mars rover next to its landing platform, captured with a wireless camera. Source: China National Space Administration. Image credit: China National Space Administration

2

FAST details active repeating fast radio bursts

Fast radio bursts (FRBs) are the most violent explosive phenomena in the radio band of the universe. Their origin is unknown and they are one of the major hot frontiers in the field of astronomy.

The team led by Li Di from the National Astronomical Observatory of the Chinese Academy of Sciences, in collaboration with the teams from Peking University, Zhijiang Laboratory and Shanghai Astronomical Observatory of the Chinese Academy of Sciences, used FAST to discover the world's first continuously active fast radio burst, FRB20190520B, which has the largest known environmental electron density and has effectively promoted multi-band research on FRBs. By monitoring the active repeating burst FRB20201124A, the largest FRB polarization sample to date was obtained, and the magnetic field changes in the local environment of FRBs and their frequency-dependent polarization oscillation phenomena were detected. For active repeating bursts represented by FRB20190520B and FRB20201124A, international cooperation was organized, especially the coordinated observation of FAST by the large telescope GBT in the United States, which revealed a single parameter describing the environment around FRBs, namely "RM dispersion", and proposed a unified mechanism for the evolution of the polarization frequency of repeating fast radio bursts.

FAST carefully depicts active and repeating fast radio bursts and constructs a unified picture, laying the observational foundation for ultimately revealing the origin of fast radio bursts.

China's Sky Eye discovers repeating fast radio bursts

3

A new principle for direct hydrogen production from seawater electrolysis

Problems such as side reactions and corrosiveness caused by the complex components of seawater have always been major difficulties that are difficult to solve in the direct electrolysis of seawater to produce hydrogen.

Xie Heping's team from Shenzhen University/Sichuan University has pioneered a new principle and technology for in-situ direct hydrogen production by electrolysis of seawater by combining physical and mechanical processes such as molecular diffusion and interfacial phase equilibrium with electrochemical reactions. They have established a theoretical method for direct hydrogen production by electrolysis of seawater through self-migration and self-driving of phase change at the gas-liquid interface, formed a mechanical driving mechanism for spontaneous phase change and mass transfer of seawater due to interfacial pressure difference, and achieved dynamic self-regulating and stable direct hydrogen production by electrolysis of seawater through coordinated seawater migration with electrochemical reactions without additional energy consumption.

The independently developed 386 L/h H2 principle prototype has stably produced hydrogen in real seawater for more than 3,200 hours, with a Faraday efficiency of nearly 100% and an electrolysis energy consumption of approximately 5.0 kWh/Nm3 H2. While isolating seawater ions, it has achieved a technological breakthrough in efficient in-situ direct seawater electrolysis for hydrogen production without a desalination process, side reactions, or additional energy consumption, laying the foundation for solving the technical problems that have long plagued the scientific and industrial communities in this field.

4

Revealing the mutation characteristics and immune escape mechanism of the new coronavirus

The SARS-CoV-2 Omicron mutant strains and their variants continue to emerge. It is crucial to promptly analyze how the SARS-CoV-2 mutant strains escape the immune barrier established by vaccination and the human immunity generated by viral infection for future vaccine design and epidemic prevention and control.

The teams of Cao Yunlong and Xie Xiaoliang from Peking University and Beijing Changping Laboratory, in collaboration with the team of Wang Xiangxi from the Institute of Biophysics of the Chinese Academy of Sciences, were the first to reveal the humoral immune escape mechanism and mutational evolution characteristics of the new coronavirus Omicron mutant strain and its new subtype, and the escape mechanism of the neutralizing antibody Omicron BA.1 and its connection with the structural characteristics of the viral spike protein; they found that the Omicron BA.4/BA.5 mutations can escape the neutralizing antibodies produced after human infection with BA.1, proving that it is difficult to achieve herd immunity through Omicron infection to block the spread of the new coronavirus; based on the independently developed high-throughput mutation scanning technology, they successfully predicted the immune escape mutation sites in the receptor binding domain of the new coronavirus, and prospectively screened out broad-spectrum neutralizing antibodies for the new coronavirus.

The relevant research provides a theoretical basis and design guidance for the development of broad-spectrum new crown vaccines and antibody drugs, and provides an important reference for the global new crown epidemic prevention and control.

5

Achieving high-efficiency all-perovskite tandem solar cells and modules

Perovskite tandem solar cells have the advantage of low-cost solution processing and show important prospects in the large-scale application of thin-film solar cells. However, the photoelectric conversion efficiency of all-perovskite tandem cells is still lower than that of single-junction perovskite cells. The high surface defect density of narrow-bandgap perovskite grains is the key bottleneck restricting the improvement of tandem cell efficiency.

The team led by Tan Hairen of Nanjing University designed the polarity of the passivation molecules to enhance their adsorption strength on the surface defect sites of narrow-bandgap perovskite grains, significantly enhancing defect passivation and greatly improving the efficiency of all-perovskite tandem cells. Independently tested by the internationally authoritative testing agency Japan Electrical Safety and Environmental Research Institute (JET), the efficiency of the tandem cells reached 26.4%, setting a new record for perovskite cells and surpassing single-junction perovskite cells for the first time, which is comparable to the highest efficiency of mainstream crystalline silicon cells on the market.

The team has developed a mass-producible preparation technology for large-area laminated photovoltaic modules, using a dense semiconductor conformal layer to block the contact between the perovskite and the metal back electrode in the interconnection area of ​​the module, significantly improving the photovoltaic performance and stability of the module, and achieving an internationally certified laminated module efficiency of 21.7% (area 20 cm2).

6

New principle switching device provides new solution for high-performance mass storage

High-density and massive storage are key bottlenecks in the development of information technology and digital economy in the era of big data.

The team led by Song Zhitang and Zhu Min from the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, has invented a new switching device based on the interface effect of single-element tellurium and titanium nitride electrodes. This device fully leverages the unique advantages of fast tellurium melting and crystallization and low power consumption in the two-dimensional confined structure at the nanoscale. In the "on state", tellurium is in a molten state and is metal-like, forming an ohmic contact with the titanium nitride electrode, providing a strong current driving capability. In the "off state", the semiconductor single-element tellurium and the titanium nitride electrode form a Schottky barrier, completely cutting off the current.

The new switch device of crystal-liquid transition has simple components and can overcome the problem of component segregation caused by complex components of bidirectional threshold switch (OTS); the process is compatible with CMOS and can be extremely miniaturized, which is easy to achieve massive three-dimensional integration; the switch has excellent comprehensive performance, with a driving current of 11 MA/cm2, a fatigue life of >108 times, and a switching speed of about 15ns. In particular, the switch life can be greatly improved if the tellurium atom is not lost. This research provides a new technical solution for the development of massive storage and near-memory computing.

7

Achieving quantum coherent synthesis of ultracold triatomic molecules

Using highly controllable ultracold molecules to simulate complex and difficult-to-calculate chemical reactions allows for precise and comprehensive studies of complex systems.

Since Deborah Jin's research group at the University of Colorado synthesized potassium diatomic molecules from ultracold atomic gas in 2003, various ultracold diatomic molecules have been prepared in other laboratories and widely used in ultracold chemistry and quantum simulation research. The energy level structure of triatomic molecules is difficult to calculate in theory and extremely difficult to manipulate experimentally, so the preparation of ultracold triatomic molecules has always been a huge experimental challenge.

The team of Pan Jianwei and Zhao Bo from the University of Science and Technology of China, in collaboration with the team of Bai Chunli from the Institute of Chemistry of the Chinese Academy of Sciences, coherently synthesized ultracold triatomic molecules for the first time in a mixture of sodium-potassium ground state molecules and potassium atoms near the molecule-atom Feshbach resonance using radio frequency synthesis technology. This research has opened up a new direction for the study of ultracold chemistry and quantum simulation.

8

Ethylene glycol synthesis under mild pressure conditions

At present, the global annual demand for ethylene glycol reaches tens of millions of tons, mainly from petrochemicals. In order to reduce the external dependence of ethylene glycol, scientific research institutions represented by the Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences cooperated with enterprises to develop a full set of non-petroleum route technologies for converting coal or synthesis gas into ethylene glycol through ester hydrogenation in 2009. However, there are safety hazards and the purity and quality of ethylene glycol products are not stable enough in this technical route.

The teams led by Xie Suyuan and Yuan Youzhu from Xiamen University, in collaboration with researchers from the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, and Xiamen Funa New Materials Technology Co., Ltd., used fullerene C60 as an "electron buffer" to modify copper-silica catalysts. They developed a cuprous fullerene-copper-silica catalyst that uses C60 electron buffering to stabilize the catalyst. They achieved the fullerene-buffered copper-catalyzed synthesis of ethylene glycol from dimethyl oxalate at a scale of several kilograms under mild pressure conditions, which is expected to reduce dependence on petroleum technology routes.

9

Discovery of a new mechanism for femtosecond laser-induced micro-nanostructuring of complex systems

When femtosecond lasers are focused into a material, a variety of highly nonlinear effects occur. The interaction between light and matter under such extreme conditions is full of unknowns and challenges.

The team led by Qiu Jianrong of Zhejiang University and their collaborators have discovered a new mechanism for the formation of micro-nano structures in complex systems induced by femtosecond lasers. Taking the oxide glass system containing chlorine, bromide and iodine ions as an example, they have realized the 3D direct lithography of perovskite nanocrystals with controllable composition and bandgap luminescence in glass, showing different colors of luminescence such as red, orange, yellow, green and blue. The formed nanocrystals showed remarkable stability in ultraviolet irradiation, organic solution immersion and 250°C high temperature environment. They further demonstrated the ultra-large capacity and long-life information storage of this 3D micro-nano structure, and the highly stable micro-LED array with the smallest pixel size of micrometers, realizing a 1080p level dynamic stereoscopic color holographic display.

This achievement reveals the laws of femtosecond laser-induced spatially selective mesoscopic-scale phase separation and ion exchange, and opens up new technical principles for femtosecond laser three-dimensional extreme manufacturing.

10

Experiment confirms superconducting state "segmented Fermi surface"

The Fermi surface determines the electrical, optical and other physical properties of solid materials. Artificial control of the Fermi surface is the most important way to control the physical properties of materials. Superconductors have no Fermi surface because they have an energy gap at the Fermi level. In 1965, Peter Fulde theoretically predicted that if the Cooper pairs in a superconductor were moved and their momentum increased, the Cooper pairs would break up and a special "segmented Fermi surface" would be generated in the superconducting energy gap.

The team of Jia Jinfeng and Zheng Hao from Shanghai Jiao Tong University collaborated with the team of Fu Liang from MIT to design and prepare a topological insulator/superconductor (Bi2Te3/NbSe2) heterojunction system, inducing superconductivity in Bi2Te3 with the help of the superconducting proximity effect, and using a horizontal magnetic field to generate a small Cooper pair momentum in the system. Thanks to the unique advantage of the extremely high Fermi velocity of the topological surface state of Bi2Te3, the Cooper pairs in the topological surface state have been broken, and this special "segmented Fermi surface" was finally realized and observed, successfully verifying the theoretical prediction made 58 years ago. This research has opened up a new method for regulating the state of matter and constructing new topological superconductors.

Source: Science and Technology Daily