Photocatalytic hydrogen evolution over the isostructural titanates: Ba3Li2Ti8O20 and Na2Ti6O13 modified with metal oxide nanoparticles

• Published in: International journal of hydrogen energy Vol. 43; no. 4; pp. 2148 - 2159
• Main Authors: Garay-Rodríguez, Luis F., Huerta-Flores, Ali M., Torres-Martínez, Leticia M., Moctezuma, Edgar
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 25-01-2018
• Subjects: Cocatalysts; Hydrogen evolution; Titanates; Tunnel structure; Tunnel structure; Cocatalysts; Titanates; Hydrogen evolution
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2017.12.004

Isostructural titanates exhibiting rectangular tunnel structure with the general formula Na2Ti6O13 and Ba3Li2Ti8O20, were synthesized by solid state and sol-gel methods. The structural, morphological, optical, textural and electrical properties of the materials were characterized by XRD, SEM, UV-vis, BET and EIS. The photocatalytic activity for hydrogen evolution of the materials was evaluated under UV light. Na2Ti6O13 exhibited higher activity (120 μmol/gh) than Ba3Li2Ti8O20 (30 μmol/gh), and it was attributed to the distortion of the octahedrons in Ba3Li2Ti8O20, which increases the recombination of charges in the material. Additionally, the 1D dimension obtained in Na2Ti6O13 promotes a better charge separation, transport and utilization in this phase. The activity of the materials was enhanced with the incorporation of metal oxide nanoparticles MO (M = Cu, Ni) as cocatalysts. The activity of Ba3Li2Ti8O20 increased 10 times with the addition of CuO (240 μmol/gh), while the activity of Na2Ti6O13 increased 3.5 times (416 μmol/gh). This improvement in the photocatalytic activity of the isostructural titanates was attributed to the formation of a p-n heterostructure between n-type titanates and p-type CuO, which promoted an enhanced charge separation, transference and utilization.
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•Photocatalytic H2 evolution on Ba and Na tunnel isostructural titanates is studied.•Activity of Ba3Li2Ti8O20 (30 μmol/gh) is reported herein for the first time.•A correlation of physicochemical properties with catalytic activity is discussed.•Deposition of CuO and NiO nanoparticles increased significantly the H2 evolution.•The highest activity was obtained by Na2Ti6O13 modified with CuO (416 μmol/gh).