AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS1-TuM

Paper SS1-TuM5
Formic Acid Decomposition on Pd Nanoparticles Deposited on TiO@sub 2@(110)

Tuesday, November 14, 2006, 9:20 am, Room 2002

Session: Reactivity of Metal Clusters
Presenter: J. Zhou, Oak Ridge National Laboratory
Authors: J. Zhou, Oak Ridge National Laboratory
S. Dag, Oak Ridge National Laboratory
V. Meunier, Oak Ridge National Laboratory
S.V. Kalinin, Oak Ridge National Laboratory
D.R. Mullins, Oak Ridge National Laboratory
S.H. Overbury, Oak Ridge National Laboratory
A.P. Baddorf, Oak Ridge National Laboratory
Correspondent: Click to Email
Adsorption and dissociation of formic acid molecules on clean TiO@sub 2@(110) and on TiO@sub 2@(110) with deposited Pd nanoparticles were investigated using scanning tunneling microscopy (STM), temperature programmed desorption (TPD) and first-principles calculations. Our TPD data indicate that formic acid can decompose on bare titania and produce CO, CO@sub 2@, H@sub 2@ and H@sub 2@O upon heating after adsorption at 110 K. H@sub 2@ was detected in multiple peaks between 200 K and 600 K, while CO and CO@sub 2@ desorbed with a single peak around 550 K and H@sub 2@O evolved at 270 K. After deposition of Pd to titania, formic acid dissociation was greatly enhanced. Furthermore, multiple CO, CO@sub 2@ and H@sub 2@ desorption peaks were observed. At 300 K, individual species were seen bonded to the atomic Ti rows in the STM image, due to the formate formation after adsorption. Bonding of formate on reduced 1x2 strands was also observed in our study. Formate was further identified near and on Pd particles by STM at 300 K. Upon heating to 375 K, formate reacted to form a new species observed bridging the Ti rows. An atomic scale understanding of the experimental STM images is provided from detailed first-principles calculations. Research was sponsored by the Laboratory Directed Research and Development Program of ORNL, managed by UT-Battelle, LLC for the U. S. DOE under Contract DE-AC05-00OR22725.