Hydrogen photoproduction using methanol:water
mixtures was essayed
with PtRu titania-based materials. All materials contain a high-surface-area
Nb-doped anatase support. Six bimetallic formulations with Pt:Ru ratios
from 4:1 to 1:4 and two (Pt and Ru) monometallic reference samples
were utilized. The catalytic response of the materials to three main
experimental variables (methanol:water molar ratio, catalyst concentration,
and light intensity) was studied through a Box–Benhken factorial
design and the calculation of the true quantum efficiency. The optimum
activity is achieved using a bimetallic PtRu (2:1) composition,
which provides outstanding efficiency under ultraviolet (UV), visible,
and sunlight illumination, as well as long-term stability. The interpretation
of the activity was performed using characterization results, the
outcome of an analysis of charge recombination with photoluminescence
spectroscopy and of an in situ infrared study under reaction conditions.
This proves that the photophysical and chemical properties of metallic
Pt particles in contact with Ru oxidized particles are key to render
highly active systems.