On one hand, co-catalysts can effectively lower the barrier for
CO2 activation, owing to their better conductivity and lower over
potential. For example, it is reported that the activation energy
of Ea for commercial P25 and 3 wt% CuO loaded P25 is ca. +26
and +12 kJ/mol, respectively [101]. The apparent lower activation
energy of the latter hence can improve the efficiency of CO2 reduction.
One-dimensional (1D) structured TiO2 single crystals coated
with ultrafine Pt nanoparticles (NPs, 0.5–2 nm) exhibit extremely
high CO2 photoreduction efficiency with selective formation of
methane, partially attributed to the efficient electron–hole separation
by the Pt NPs [102]. Recently, Yu and co-workers have reported
that the deposition of Pt is a good strategy to improve the photoactivity
and selectivity of graphitic carbon nitride (g-C3N4) for CO2
reduction [103]. It has been shown that the Pt NPs deposited on the
surface of g-C3N4 can lower the overpotential, as well as facilitate
electron transfer and enrich more photogenerated electrons on its
surface for photocatalytic reduction of CO2.