Different morphologies of ZnO (Hollow spheres and Bucky bowls) and graphene oxide/ZnO hybrid structures (nanorod and triangle shaped) were synthesized via a facile hydrothermal method. The structural evolution of pristine ZnO and GO-ZnO hybrid structures were examined in detail over both the experimental and analytical means (deformation models). Herein, the simultaneous effect of dislocation driven growth and Layer by Layer growth is a favored mechanism for GO-ZnO triangles. Furthermore, the oxygen vacancies (V-O) in GO-ZnO strongly influence the photoelectrochemical (PEC) performances in two faced effect. The GO-ZnO triangle-shaped composites exhibit the maximum overall water splitting photocurrent density of similar to 1.517 mA/cm(-2) at 1.45 V vs RHE with the highest enhancement in the Incident Photon to Current conversion Efficiency (IPCE) of 10.41%, which is similar to 3.30 and 2.08 times higher than pristine ZnO Hollow spheres and Bucky bowls respectively. Besides, the similar strategy of GO-ZnO triangle shaped nanocomposites exhibit similar to 1.82 times higher than the GO-ZnO nanorod. Hence, the overall improvement in the GO-ZnO triangle shape in comparisons with pristine ZnO samples and/or GO-ZnO rods is due to the increased amounts of oxygen vacancies to some extent. (C) 2016 Elsevier B.V. All rights reserved.