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

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. © 2017 Hydrogen Energy Publications LLC

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