Bimetallic Pt-Pd co-catalyst Nb-doped TiO2 materials for H2 photo-production under UV and Visible light illumination

• Published in: Applied catalysis. B, Environmental Vol. 238; pp. 533 - 545
• Main Authors: Caudillo-Flores, Uriel, Muñoz-Batista, Mario J., Fernández-García, Marcos, Kubacka, Anna
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2018
• Subjects: Bimetallic co-catalyst; In-situ FTIR; Quantum efficiency and yield; Sunlight; Visible; Visible; Sunlight; Quantum efficiency and yield; UV; In-situ FTIR; Bimetallic co-catalyst
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.07.047

[Display omitted] •Pt-Pd cocatalyst(s) tested under UV and Visible light hydrogen photo-production.•Analysis of activity by means of the true quantum efficiency.•Pt:Pd 1:1 optimizes activity under all illumination conditions tested.•Bimetallic cocatalysts evolve under reaction conditions.•Activity depends critically on PtPd alloying and metal-support interface. properties In this work we synthesized a series of binary PtPd co-catalysts supported on a Nb-doped TiO2 support. The catalytic solids and corresponding monometallic reference systems are characterized using X-ray diffraction, X-ray photoelectron, and UV–vis spectroscopies, together with microscopy and porosimetry tools. Such characterization was able to show the formation of PtPd alloy particles in the bimetallic catalysts. The mono and bimetallic TiO2-based powders were tested in the photo-production of hydrogen from methanol:water mixtures under UV and visible illumination conditions. Analysis of catalytic properties was carried out through the measurement of the optical properties of the materials and the calculation of the true quantum efficiency parameter. Results indicate that the PtPd co-catalysts have superior performance that the Pt and Pd monometallic counterparts both under UV and visible illumination conditions. Optimum performance was achieved with a material having a Pt:Pd 1:1 atomic ratio. A remarkable increase in the use of the visible range and thus in sunlight utilization is achieved with the 1:1 Pt:Pd bimetallic system with respect to the monometallic counterparts. The evolution of the bimetallic co-catalysts under reaction conditions as well as their key properties to interpret photo-activity were analyzed with the help of the above mentioned techniques as well as photoluminescence spectroscopy and an in-situ infrared analysis of the materials under reaction conditions. Results point out the critical role that both PtPd alloying and the metal-support interface play in the reaction.