Researchers at the Ulsan National Institute of Science and Technology and Seoul National University have developed a germanium and titanium co-doped iron oxide photoanode for hydrogen production, according to a study published in Nature Communications. The system couples glycerol oxidation with cathodic hydrogen evolution under simulated one-sun illumination of 100 milliwatts per square centimetre.
In a 1.0 M sodium hydroxide solution containing 2.0 M glycerol, the photoanode achieved a photocurrent density of 8.87 milliamperes per square centimetre at 1.23 volts versus the reversible hydrogen electrode. That performance surpasses the established practical benchmark of 8.1 milliamperes per square centimetre.
Iron oxide offers high natural abundance, a suitable band gap, and stability in water. Poor charge transport and sluggish water oxidation have previously limited its practical application in photoelectrochemical water splitting.
Selective Oxidation and Mechanics
Germanium incorporation enables the selective oxidation of glycerol into tartronic acid, a value-added chemical product. Electrochemical testing and density functional theory calculations show that co-doping with titanium and germanium improves overall charge use, while germanium specifically promotes the tartronic acid-forming pathway.
Sarang Kim, Juhyung Park, and Jinwoo Hwang contributed equally to the work. The research team included scientists from UNIST's School of Energy and Chemical Engineering, School of Semiconductor Materials and Devices Engineering, Graduate School of Carbon Neutrality, and Emergent Hydrogen Technology R&D Centre, alongside Seoul National University's Department of Materials Science and Engineering.
The South Korean Ministry of Science and ICT funded the study through National Research Foundation grants and the InnoCORE program. UNIST provided additional financial support through its 2026 Research Fund.
