Water/InP(001) from Density Functional Theory

Abstract

The interface between water and the In-rich InP(001) surface is studied by density functional theory with water coverage ranging from single molecules to multiple overlayers. Single molecules attach preferably to three-fold coordinated surface In atoms. Water dissociation is energetically favorable but hindered by an energy barrier that decreases with increasing water coverage. There is an attractive interaction between InP adsorbed water molecules that leads to the formation of molecular clusters and complete water films for water-rich preparation conditions. Water films on InP are stabilized by anchoring to surface-bonded hydroxyl groups. With increasing thickness, the water films resemble the structural properties of ice Ih. The oxygen and hydrogen evolution reactions on InP are characterized by overpotentials of the order of 1.7–1.8 and 0.2–0.3 eV, respectively. While the calculated bulk positions of the InP band edges are outside the range of the redox potentials for oxygen and hydrogen evolution within local DFT, the situation is different at the actual interface: Here, the interface dipole lifts the InP valence band maximum above the redox potential for oxygen evolution and favors hydrogen evolution.

P-Terminated InP (001) Surfaces: Surface Band Bending and Reactivity to Water

“…This also confirms that the P dangling bond center itself is not the active site for water dissociation because beyond the H vacancy as a stable OH site, a neighboring active site for the remaining H adsorption as a further product of H 2 O dissociation is missing. Furthermore, recent studies on In-rich InP (001) suggest that free In sites are required for the dissociation of molecular water on InP surfaces . For that reason, we suggest that water dissociation only occurs at step edges rather than on terraces of the P-rich InP (001) surface.…”

The interfacial structure of InP(100) in contact with HCl and H2SO4 studied by reflection anisotropy spectroscopy

“…This would be compatible with the adsorption of chloride on an In-terminated surface, leading to the formation of an InCl surface film starting from −0.55 V (Ag/AgCl), 22 which would also explain the differences at lower photon energies to H 2 SO 4 . The further change of the anisotropy at cathodic potentials beyond −1.5 V could then be related to the reordering of the (near-)interface water 26 or the adsorption of protons/hydrogen on the surface.…”

“…24 Computational studies have reported on the structure and electronic properties of the pristine and oxidised InP surface using density-functional theory as well as molecular dynamics. 18,26,27 Wood et al 18 investigated the interaction of gasphase and liquid water with the pristine and oxygen-rich surfaces. Alvarado et al 26,27 changed water coverage adsorbed on InP from single molecules to water lm, and they found the OER and HER energetics to be modied due to the adsorption.…”

“…18,26,27 Wood et al 18 investigated the interaction of gasphase and liquid water with the pristine and oxygen-rich surfaces. Alvarado et al 26,27 changed water coverage adsorbed on InP from single molecules to water lm, and they found the OER and HER energetics to be modied due to the adsorption.…”

Semiconductor Catalysts for Oxygen and Hydrogen Evolution Reactions

“…InP coated with Pt possesses photovoltage of 0.63 V for HER. , The calculated overpotential of InP for HER by density functional theory is 0.2–0.3 V, while we are not aware of the literature data on the measured overpotential. Tafel slopes 120 and 310 mV/dec were observed for HER on the illuminated p-InP in 1 M H 2 SO 4 solution, Figure .…”