Graphene oxide (GO) sheets have extremely adjustable electronic characteristics due to their distinctive 2D carbon composition, allowing comprehensive surface modifications. Photodriven water splitting uses semiconducting materials that have water-decomposition electronic structures appropriate for electron and hole injection. Photoelectrochemical (PEC) is regarded as an extremely efficient energy conversion system for the manufacturing of clean solar fuel. There have been tremendous attempts to design and create feasible unassisted PEC systems that can effectively divide water to form hydrogen gas and oxygen with only solar energy input (sunlight) necessary. In particular, in the presence of a photocatalyst modified with an appropriate cocatalyst, overall PEC water splitting can be accomplished. For the development of PEC systems, the fundamental concept of PEC water splitting and enhanced energy-conversion efficiency are essential for solar fuel manufacturing. Therefore, this review paper provides a concise summary of unassisted PEC systems with state-of-the-art advancements towards effective PEC water-splitting equipment for the sustainable future use of solar energy. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.