Photocatalytic hydrogen evolution using bi-metallic (Ni/pt) na 2 ti 3 o 7 whiskers: Effect of the deposition order

Photocatalytic hydrogen production through ethanol photo-reforming using Na 2 Ti 3 O 7 whiskers increases if the sodium titanate is decorated with well-known metallic catalysts such as Ni and Pt. Whereas wet impregnation with nickel gives only a slight increase in the activity, photodeposition of Pt increased the H 2 production by more than one order of magnitude. Through the combination of both co-catalysts (Ni and Pt) a superior performance in terms of H 2 production is further observed. However, hydrogen yield is largely enhanced (almost three-fold), up to 778 μmol·g −1 ·h −1 , if the Pt is photo-deposited on the surface of the catalyst before wet impregnation with Ni species (NTO/Pt/Ni) compared to H 2 yield (283 μmol·g −1 ·h −1 ) achieved with the catalyst prepared in the reverse order (NTO/Ni/Pt). Structural, morphological, optical, and chemical characterization was carried out in order to correlate physicochemical properties with their photocatalytic activity. The X-ray photoelectron spectroscopy (XPS) results show a higher concentration of Pt 2 %2b species if this metallic layer is under the nickel oxide layer. Moreover, X-ray diffraction patterns (XRD) show that Na 2 Ti 3 O 7 surface is modified for both metal decoration processes. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

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