# Revealing the Intricate Structure of Surface Phases of Methanol on In2O3(111)

## TL;DR

This study explores how methanol interacts with the In2O3(111) surface, revealing structural changes and comparing them to water adsorption under various conditions.

## Contribution

The paper provides new insights into methanol adsorption mechanisms on In2O3(111) surfaces using advanced experimental and theoretical methods.

## Key findings

- At low coverage, methanol adsorption on In2O3(111) resembles water adsorption, with dissociative and molecular adsorption patterns.
- Molecular adsorption becomes favored for methanol at temperatures below 300 K after the first three molecules dissociate.
- At high coverage, methanol and water form distinct structures due to differences in hydrogen bonding capabilities.

## Abstract

Research on sustainable
energy has intensified to reduce greenhouse
gas emissions, especially CO2. One promising strategy is
the catalytic reduction of CO2 to methanol, and indium
oxide (In2O3) has emerged as a highly efficient
catalyst, with high turnover rates and selectivity. This work investigates
methanol, the end product of CO2 reduction, and its interaction
with the In2O3(111) surface. Utilizing an ultrahigh
vacuum (UHV) environment, this study combines temperature-programmed
desorption (TPD), X-ray photoelectron spectroscopy (XPS), noncontact
atomic force microscopy (nc-AFM), scanning tunneling microscopy (STM),
and density functional theory (DFT) calculations. The coverages investigated
range from 1 to 12 methanol molecules per unit cell. The results are
compared to water adsorption on In2O3(111),
as the chemical behavior of both molecules is similar in many respects.
At low coverage, the adsorption patterns and interactions with the
In2O3(111) surface mirror those seen with water,
including dissociative and molecular adsorption. The first three methanol
molecules dissociate at specific sites within the surface unit cell,
while molecular adsorption becomes favored for subsequent molecules
at temperatures below 300 K. At the highest coverage (before multilayer
adsorption) methanol and water exhibit distinct structures due to
their differing hydrogen bonding capabilities.