Muhammad Tsabit Ayman, Gracia Cahyadi, Aliya Asiyani Ainul Arofi, Didik Aryanto, Faried Latief, Hendri Erka Setya, Bagas Haqi Arrosyid, Nanda Hendra Pratama, Gilang Awan Yudhistira, Gian Villany Golwa, Alfian Noviyanto
Calcium titanate (CaTiO3) is a durable perovskite oxide, but its wide bandgap usually limits photocatalytic activity to the UV spectrum. This study compares three hydrothermal synthesis routes, sol-gel-assisted (CTO-SGH), direct (CTO-DH), and titration-assisted (CTO-TH), with two solid-state methods using rutile and anatase TiO2 (CTO-SS-R, CTO-SS-A) to assess their effects on defect chemistry, bandgap, and photocatalytic performance for methylene blue (MB) degradation. All samples crystallize in the orthorhombic Pbnm. SEM and particle size analysis showed that CTO-DH and CTO-TH produce smaller, less agglomerated particles than CTO-SGH and solid-state methods. Raman spectroscopy indicated CTO-DH has the most ordered lattice structure among the hydrothermal routes. UV–vis spectroscopy revealed CTO-DH exhibits a significantly narrowed bandgap (1.97 eV) compared to 2.77–3.38 eV for other samples, suggesting enhanced visible-light absorption due to defect-mediated states. As a result, CTO-DH achieves nearly complete MB degradation in 180 min under sunlight, with a rate constant of 0.0012 min−1, about twice that of CTO-SGH and much higher than the solid-state samples. CTO-DH also outperforms others under UV light. Radical scavenger tests identify hydroxyl and superoxide species as the main oxidants. This work demonstrates that direct hydrothermal synthesis is an effective, simple route to engineer low-bandgap CaTiO3 with superior solar photocatalytic efficiency, offering valuable insights for designing perovskite photocatalysts for water remediation. © 2026 Elsevier Ltd and Techna Group S.r.l. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Research Center for Composite and Biomaterials, National Research and Innovation Agency, KST BJ. Habibie Serpong, Banten, South Tangerang, 15314, Indonesia; Department of Chemistry, Brawijaya University, Malang, 65145, Indonesia; Research Center for Energy Materials, National Research and Innovation Agency, KST BJ. Habibie Serpong, Banten, South Tangerang, 15314, Indonesia; Center of Excellence Advanced Materials, Nano Center Indonesia, Jl. Puspiptek, Banten, South Tangerang, 15314, Indonesia; Department of Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Bandung, 40132, Indonesia; Department of Mechanical Engineering, Mercu Buana University, Jl. Meruya Selatan, Kebun Jeruk, Jakarta, 11650, Indonesia
