CO2 dissociation activated through electron attachment on reduced rutile TiO2(110)-1x1 surface

TL;DR

This study investigates how electron attachment activates CO2 dissociation on reduced rutile TiO2(110) surfaces, providing fundamental parameters crucial for designing efficient photocatalysts for CO2 reduction.

Contribution

It offers the first systematic measurement of CO2 dissociation energy thresholds and rates on TiO2 surfaces, clarifying the electron attachment process involved in photocatalytic reduction.

Findings

CO2 dissociation is activated by electron attachment with a threshold of 2.3 eV above the conduction band

Dissociation rate varies with electron injection energy

Provides fundamental parameters for catalyst design in CO2 photoreduction

Abstract

Converting CO$_2$ to useful compounds through the solar photocatalytic reduction has been one of the most promising strategies for artificial carbon recycling. The highly relevant photocatalytic substrate for CO$_2$ conversion has been the popular TiO$_2$ surfaces. However, the lack of accurate fundamental parameters that determine the CO$_2$ reduction on TiO$_2$ has limited our ability to control these complicated photocatalysis processes. We have systematically studied the reduction of CO2 at specific sites of the rutile TiO$_2$(110)-1x1 surface using scanning tunneling microscopy at 80 K. The dissociation of CO2 molecules is found to be activated by one electron attachment process and its energy threshold, corresponding to the CO$_2^{\dot-}$/CO$_2$ redox potential, is unambiguously determined to be 2.3 eV higher than the onset of the TiO$_2$ conduction band. The dissociation rate as a function of electron injection energy is also provided. Such information can be used as practical guidelines for the design of effective catalysts for CO$_2$ photoreduction.