Kim, Minseo Jung, Hyeonmin Cho, Hyekyung Joo, Hyunku Kang, Kyoung-Soo Kim, Hansung Yi, Kwangbok Yoon, Yeomin Yoon, Jaekyung 2026-02-19T07:30:04Z 2026-02-19T07:30:04Z 2026-02-19 2026-05 0169-4332 https://pubs.kist.re.kr/handle/201004/154330 In this study, the electronic structure of TiO2 nanotubes (TNTs) was modified through holmium(Ho) doping and europium(Eu) photodeposition to enhance photoelectrochemical (PEC) water splitting performance. Ho doping introduced impurity energy levels (IEL) within the band gap, while Eu photodeposition generated oxygen vacancies whose concentration correlated with the Eu(II)/(Eu(II) + Eu(III)) ratio depending on the photodeposition time (30, 60, 90, and 120 min). Among the prepared samples, the one treated for 90 min (EH90-TNTs) exhibited the highest photoactivity, as verified by a series of electrochemical and optical analyses. PEC water splitting experiments revealed that the hydrogen evolution rate and photocurrent density of EH90-TNTs increased by 25.4% and 22.8%, respectively, compared with those of Ho-TNTs. This enhancement is attributed to the synergistic effect between IEL and oxygen vacancies, which suppresses photogenerated charge recombination and extends light absorption into the visible region. These findings demonstrate that the coexistence of lanthanideinduced IEL and oxygen vacancies provides an effective strategy for improving the efficiency of TiO2-based photoanodes. English Elsevier BV Improvement of electrochemical properties and hydrogen production by Ho-Eu-TiO2 nanotubes Article 10.1016/j.apsusc.2026.166074 1 Applied Surface Science, v.728 Applied Surface Science 728 N scie scopus 001681725200001 2-s2.0-105028891929 Chemistry, Physical Materials Science, Coatings & Films Physics, Applied Physics, Condensed Matter Chemistry Materials Science Physics Article OXYGEN VACANCY DOPED TIO2 PHOTOLUMINESCENCE NANOPARTICLES GENERATION CONVERSION DRIVEN TiO 2 nanotubes (TNTs) Photocatalyst Lanthanides Holmium(Ho) Europium(Eu) Hydrogen