Reviewed by Lexie CornerApr 9 2025
Researchers at the Chinese Academy of Sciences have developed a scandium (Sc)-doped titanium dioxide (TiO2) semiconductor in the rutile crystal phase.
Schematic diagram of TiO2 facet control and defect elimination. Image Credit: IMR
Photocatalytic water splitting is a clean energy technology that uses sunlight and a photocatalyst to split water into oxygen and hydrogen, producing environmentally friendly green hydrogen without relying on fossil fuels.
Titanium dioxide (TiO2) has been extensively studied as a promising semiconductor for this process. However, its efficiency has been limited by rapid charge recombination and inadequate charge separation.
A research team led by Professor Gang Liu from the Institute of Metal Research (IMR) at the Chinese Academy of Sciences (CAS) has made a significant advancement in photocatalytic water splitting.
This new material achieved an apparent quantum yield (AQY) of 30.3 %, which measures the efficiency of photon conversion to useful water splitting, and a solar-to-hydrogen (STH) efficiency of 0.34 %, representing the percentage of solar energy converted into hydrogen energy. Both of these values set new records for TiO2-based photocatalytic overall water splitting under normal, unpressurized, and unheated conditions.
To address the limitations of TiO2, the researchers used a two-pronged approach. First, doping with Sc3+ effectively eliminated harmful Ti3+ defects, which are known to trap charges and cause energy loss. Second, they engineered a facet junction between the (101) and (110) crystal planes. This created an internal electric field that drives electrons and holes to separate facets, promoting water reduction and oxidation reactions.
“This dual approach not only minimizes defect-induced charge recombination but also mimics the efficient charge separation mechanism of p-n junctions in photovoltaic cells,” said Prof. Liu.
The study highlights the considerable commercial potential of Sc-doped TiO2, especially considering China's large reserves of titanium and scandium. With an existing industrial supply chain for titanium dioxide and advanced rare earth processing capabilities, this innovation could lead to scalable and affordable hydrogen production.
“Our design strategy—suppressing defects and leveraging crystal anisotropy—aligns perfectly with China's resource strengths and industrial infrastructure,” said Prof. Liu.
The research team's next objectives are to enhance the material's light absorption capabilities and to integrate it into solar-powered systems that can be scaled up for practical applications.
The study was funded by the National Natural Science Foundation of China, the National Key R&D Program of China, the Science and Technology Major Project of Liaoning Province, and the CAS Projects for Young Scientists in Basic Research.
Journal Reference:
Qin, F., et al. (2025) Spontaneous Exciton Dissociation in Sc-Doped Rutile TiO2 for Photocatalytic Overall Water Splitting with an Apparent Quantum Yield of 30%. Journal of the American Chemical Society. doi.org/10.1021/jacs.5c01936.