Kim, Minseo Jung, Hyeonmin Cho, Hyekyung Joo, Hyunku Kang, Kyoung-Soo Kim, Hansung Yi, Kwangbok Jung, Bongyeon Yoon, Yeomin Yoon, Jaekyung 2025-03-22T12:30:17Z 2025-03-22T12:30:17Z 2025-03-19 2025-04 0169-4332 https://pubs.kist.re.kr/handle/201004/151987 The photocatalytic hydrogen production range of anatase TiO2 lies in the ultraviolet region but can be extended to the visible-light region via lanthanide-doping-based bandgap tailoring. Holmium exhibits the highest photocatalytic activity among the lanthanides; however, the effects of the pH of the Ho precursor solution-an important surface charge attribute-on the photoelectrochemical properties of Ho-doped TiO2 nanotubes (TNTs) are unexplored. Optimal conditions for photoanode in photoelectrochemical water splitting were established by observing the effects of pH on the charge of Ho species in aqueous solutions and the surface charge of pure TNTs. Here, Ho-doped TiO2 nanotubes (Ho-TNT) were fabricated by electrochemical deposition using variable-pH Ho solutions and anodization and characterized in terms of their physicochemical and electrochemical properties and photocatalytic water splitting based hydrogen production performance. The highest photocatalytic activity (hydrogen production rate = 79.44 mu mol cm- 2h- 1, photocurrent density = 8.48 mA cm- 2, photoconversion efficiency = 7.97 % at 0 V vs. the reversible hydrogen electrode) was observed for the sample fabricated at pH 7 (H7). The research revealed that the catalytic activity of TiO2 nanotubes decorated with holmium was influenced by the pH of the Ho solution, with Ho-TNTs prepared at pH 7 demonstrating the potential of this strategy to enhance the efficiency in photoelectrochemical hydrogen production. English Elsevier BV Enhanced catalytic activity and hydrogen production of Ho-TiO2 nanotubes prepared under various pH conditions Article 10.1016/j.apsusc.2025.162484 1 Applied Surface Science, v.689 Applied Surface Science 689 Y scie scopus 001421608100001 2-s2.0-85215929670 Chemistry, Physical Materials Science, Coatings & Films Physics, Applied Physics, Condensed Matter Chemistry Materials Science Physics Article PHOTOCATALYTIC DEGRADATION LUMINESCENCE PROPERTIES DOPED TIO2 NANOPARTICLES TiO 2 nanotubes Ho-TiO 2 nanotubes Photoelectrochemical hydrogen production Bandgap engineering