posted on 2020-03-20, 11:33authored byEric M. Lopato, Emily A. Eikey, Zoe C. Simon, Seoin Back, Kevin Tran, Jacqueline Lewis, Jakub F. Kowalewski, Sadegh Yazdi, John R. Kitchin, Zachary W. Ulissi, Jill E. Millstone, Stefan Bernhard
Using
a newly designed and developed parallelized photoreactor
and colorimetric detection method, a large sampling of bimetallic
cocatalysts (Pd/Sn, Pd/Mo, Pd/Ru, Pd/Pb, Pd/Ni, Ni/Sn, Mo/Sn, and
Pt/Sn) for photocatalytic water reduction have been tested. Of these
cocatalysts, the combination of palladium and tin showed the highest
synergistic behavior and peak hydrogen gas production at a low relative
fraction of palladium. The resulting palladium/tin bimetallic cocatalysts
were characterized, and specifically, and scanning transmission electron
microscopy energy-dispersive X-ray spectroscopy indicated that palladium
and tin elements reside within the same particle. The experimental
catalytic activity for the palladium/tin mixture was compared to density
functional theory-derived energy values associated with the adsorption
of hydrogen onto a surface. This comparison demonstrated that the
typical peak found in electrochemical Sabatier volcano plots at ΔGH* = ∼0 eV were replicated in the experimental
photocatalytic system with a peak activity observed at ΔGH* = −0.036 eV. Computational confirmation of the results
expressed here demonstrates the efficacy of colorimetric detection
of hydrogen in parallel and presents a model for increasingly rapid
catalyst screening.