Due to the merits
of carbon circulation and hydrocarbon production,
solar-assisted photocatalysis has been regarded as an ideal option
for securing a sustainable future of energy and environment. In the
photocatalytic carbon cycle process, surface reactions including the
adsorption of CO
2
and the conversion of CO
2
into
CH
4
, CH
3
OH, etc. are crucial to be examined
ascribed to their significant influence on the performance of the
photocatalysis. Because the conversion reaction starts from the formation
of HCOO
•
, the density functional theory (DFT) model
was established in this study to investigate the micromechanism of
CO
2
adsorption and the conversion of CO
2
to
HCOO
•
group in the anatase Au-TiO
2
photocatalytic
system. The CO
2
adsorption bonding in six configurations
was simulated, on which basis the effects of the proportion of water
molecules and the lattice temperature increase due to the local surface
plasmon resonance (LSPR) on the photocatalytic CO
2
adsorption
and conversion were specifically analyzed. The results show that the
experimental conditions that water molecules are released before CO
2
are favorable for the formation of the adsorption configuration
in which HCOO
•
tends to be produced without the
need of reaction activation energy. This is reasonable since the intermediate
C atoms do not participate in bonding under these conditions. Moreover,
Au clusters have an insignificant influence on the adsorption behaviors
of CO
2
including the adsorption sites and configurations
on TiO
2
surfaces. As a result, the reaction rate is reduced
due to the temperature increase caused by the LSPR effect. Nevertheless,
the reaction maintains a very high rate. Interestingly, configurations
that require activation energy are also possible to be resulted, which
exerts a positive influence of temperature on the conversion rate
of CO
2
. It is found that the rate of the reaction can be
improved by approximately 1–10 times with a temperature rise
of 50 K above the ambient.