Paper SS+AS+EM-WeA3
Atomic Structure of UHV-prepared GaP(111)A Surface and its Reactivity Towards Simple Molecules

Wednesday, October 24, 2018, 3:00 pm, Room 203C

Effective pyridine-catalyzed photo-reduction of CO₂ to methanol has been demonstrated on p-type GaP(111)A photocathode. Despite the considerable effort there is still no consensus about either the molecular mechanisms of this process or the role of electrode’s surface. As a part of larger effort aimed at elucidation of the mechanisms of CO₂ photoreduction we have conducted a UHV study of the atomic-scale structure and reactivity of the single-crystal GaP(111)A surface. Atomic-resolution STM images supported by LEED data show that ion sputtered and annealed surface exhibit both 2 x 2 Ga-vacancy reconstruction and relatively disordered P-trimer formations. The stoichiometric excess of Ga leads to formation of large droplets on the surface. TPD experiments and IR spectroscopy with water and methanol demonstrate dissociative adsorption of these molecules that leads to recombinative desorption around 300 K.