<p>Hydrogen, as energy carrier, is a
zero-emission fuel. Being green and clean, it is considered to play an
important role in energy and environmental issues. Photocatalytic water
splitting is a process used to generate hydrogen from the dissociation of
water. Titanium dioxide is still the archetype material for photocatalytic
water splitting. However, because of the fast recombination of the
photo-generated exciton, the yield of the reaction is typically low. In this
work, we have modified the surface of titanium dioxide with copper and
copper/graphene to sensitise it to visible light, and to increase the spatial
charge carrier separation, thus extending the quantum yield of H<sub>2</sub> production
from methanol/water mixtures. Results showed that, in the analysed system,
exists an optimum amount of copper plus graphene (<i>i.e.</i> 0.5 mol% copper plus 0.5 wt% graphene) to grant a two-fold
increase in the photocatalytic hydrogen generation compared to that of bare
titania. That system proved itself to be complex and dynamic. This was attributed to the increased spatial charge carrier separation exploited by graphene (under 365 and 405 nm irradiation), and to the continuous reduction of Cu(II) to Cu(I) due to IFCT that has proven to be an excellent visible-light sensitiser in the copper/graphene-titania system.</p><p>Hybrid titania-copper-graphene materials could therefore be exploited in
the field of light-to-energy applications.</p>
