For example, Ohno et al.[22] showed that the monoclinic WO 3 /g-C 3 N 4 with Z-scheme exhibited good photocatalytic activity due to the facilitated transfer of electrons from CO 2 to CH 3 OH. Ying et al.[23] has proved that the (0 0 2) facets of monoclinic WO 3 could play a positive effect on the photocatalytic activity for CO 2 reduction.