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E-mail Xinhua, April 8, 2025
French sci-fi author Jules Verne predicted about 150 years ago that water would become the fuel of the future. Today, scientists are striving to turn this fantasy into reality.
Chinese researchers recently achieved a breakthrough in "photocatalytic water splitting for hydrogen production." By performing "structural reshaping" and "element substitution" on a semiconductor material, they significantly enhanced the efficiency of converting water into clean hydrogen energy by using sunlight.
Current solar-driven hydrogen production primarily relies on two methods -- one uses solar panels to generate electricity for water electrolysis, which requires complex and costly equipment, while the other employs semiconductor materials as catalysts to directly split water molecules under sunlight, according to Liu Gang, director of the Institute of Metal Research of the Chinese Academy of Sciences and leader of the research team.
The key to directly splitting water with sunlight lies in a material called titanium dioxide. When exposed to sunlight, it functions like a microscopic power plant, generating energized electron-hole pairs that break down water molecules into hydrogen and oxygen, Liu explained.
However, traditional titanium dioxide has a critical flaw -- its internal structure resembles a maze, causing the activated electrons and holes to collide randomly and recombine and annihilate within a millionth of a second. Additionally, the high-temperature fabrication process of the material often leads to oxygen atom loss, creating positively charged "trap zones" that capture electrons.
Liu's team addressed these issues by introducing scandium, a rare-earth element neighboring titanium on the periodic table, to restructure the material.
Scandium ions, similar in size to titanium ions, fit perfectly into the titanium dioxide lattice without causing structural distortion. Their stable valence neutralizes the charge imbalance caused by oxygen vacancies, eliminating "trap zones." Moreover, scandium atoms reconstruct the crystal surface, creating specific facets that act like "electronic highways and overpasses," allowing electrons and holes to escape the maze efficiently.
Through precise control, the research team successfully developed a specialized titanium dioxide material with significantly enhanced performance -- its utilization of ultraviolet light exceeded 30 percent, and its hydrogen production efficiency under simulated sunlight was 15 times higher than previously reported titanium dioxide materials, setting a new record, Liu stated.
"If used to create a one-square-meter photocatalytic material panel, around 10 liters of hydrogen can be produced in one day of sunlight," Liu said.
The achievement was published in the latest issue of the Journal of the American Chemical Society.
"We aim to further improve the technology to enable efficient utilization of visible light in sunlight," Liu revealed.
He also noted that China currently accounts for over 50 percent of global titanium dioxide production, supported by a robust industrial chain. Additionally, China ranks among the world's leaders in terms of scandium reserves.
"With continued advancements in photocatalytic water-splitting efficiency, this technology holds promise for industrial application, and could drive the transformation of energy systems," Liu added.
