Nature of Catalytic Active Surface Sites on Semiconductor Photocatalysts for Splitting of Water

Meeting Program – March 2013

Somphonh Peter Phivilay
Operando Molecular Spectroscopy & Catalysis Laboratory
Department of Chemical Engineering
Lehigh University
Bethlehem, PA 18015 USA
Student Speaker

Abstract – One of society’s great challenges for the 21st century is the development of alternative energy resources. Hydrogen is considered to be one of the potential candidates especially if it can be generated from the photocatalytic conversion of cheap abundant H2O into clean non-carbon H2 from solar energy resources. Development of this clean, renewable form of energy will help to address our reliance on depleted fossil fuel supplies and the environmental problems accompanying its use.

Photocatalytic splitting of waters proceeds via generation of excited electrons and holes in the semiconductor catalyst bulk lattice, the diffusion of the excitons through the semiconductor lattice to the surface, and surface reactions of the excitons with water to split H2O to H2 and O2. The photocatalysis literature, however, has almost completely neglected the surface nature of photocatalysts and focused on the semiconductor catalyst bulk lattice that is only responsible for generation of the excited holes and electrons.

This presentation will examine the anatomy of the supported (Rh2-yCryO3)/(Ga1-xZnx)(N1-xOx) photocatalysts that are able to split water with visible light excitation by determining the nature of the bulk lattice (mm), surface region (~1-3 nm) and outermost surface later (~0.3 nm) with unique cutting edge characterization techniques.