Effect of Metal Work Function on Hydrogen Production from Photocatalytic Water Splitting with MTiO <sub>2</sub> Catalysts
Charles Beasley, Muthu Kumaran Gnanamani, Eduardo Santillan‐Jimenez, Michela Martinelli, Wilson D. Shafer, Shelley D. Hopps, Namal Wanninayake, Doo Young Kim
Abstract
Abstract Photocatalytic water splitting was performed on TiO 2 and metal‐containing TiO 2 (MTiO 2 ) catalysts under UV light irradiation. TiO 2 was added with various metals of different work functions, namely, Pt (5.93 eV), Pd (5.60 eV), Cu (5.10 eV), Ru (4.71 eV), and Ag (4.26 eV). The hydrogen production was found to increase linearly with increasing metal work function. The rate of charge recombination increases with decreasing work function difference between the metal and TiO 2 . Pt and Pd were highly efficient co‐catalysts to TiO 2 for hydrogen generation from water due to their larger work function and upward‐bent band causing the photoelectrons to be trapped in those metal sites that are eventually consumed during water reduction. Co‐catalysts such as Ag, Ru, and Cu were less effective towards water splitting due to downward‐bent band gaps that allow the photoelectrons to flow back to TiO 2 from the metal which leads to faster charge recombination.