**6. Concluding remark and perspectives**

In summary, GRMs (GO, rGO, graphene and derivatives) can be incorporated into different semiconductors or metals to construct GRM-based composite photocatalysts. An integration of GRMs into these composites has proven to be effective approach to endow unprecedented properties and concurrently improves the high dye adsorption capability, light absorption, and also facilitate charge separation and transfer properties, enabling advancement in the overall photocatalytic activity. Despite of decades intensive research, the scalable synthesis of high-quality graphene is in unmatured state and several issues need to be addressed. We discussed simple, cost-effective synthetic strategies such as in situ reduction, coprecipitation, hydrothermal or solvothermal reactions etc. to develop emerging GRM based composites and applicability towards photocatalytic degradation of pollutant dyes, organics and pharmaceutical wastes in water.

With regard to breakthrough in photocatalysis technology, the studies are in early stage and further specific advancements are required. The following insights may be useful.

