One step electrodeposition method has been used to realize highly porous ZnO pin hole (ZP) and ZnO rosette sheets (ZS) nanostructure based photo-anodes for efficient photo-electrochemical (PEC) splitting of water. Electrodeposited ZP and ZS based photo-anodes exhibit enhanced photocurrent density of 0.62 mA/cm(2) and 0.76 mA/cm(2) respectively (at a bias of 0.75 V). Further on hydrothermal amination (A), these electrodeposited ZP and ZS (A-ZP and A-ZS) nanostructure based photo-anodes had shown enhanced photocurrent density of 1.02 mA/cm(2) and 1.27 mA/cm(2), respectively. Surface morphology, evolution and elemental study were done using FESEM and EDX. Raman spectra of aminated photo anodes have peaks at similar to 270 cm(-1) and similar to 511 cm(-1) related to stretching vibration mode between Zn-N and Zn-O. The peaks at wave number similar to 558 cm(-1) and similar to 571 cm(-1) is due to formation of Zn-C bonds and because of complex defects respectively. ZnO exhibits low PEC activity, but on nano-structuring in the form of ZP and ZS improves its light absorption capacity. Hydrothermal amination red shifts (similar to 25 nm) the absorption band at similar to 425 nm. The N and C act as electron reservoirs in A-ZP and A-ZS photo-anodes and efficiently separate the photo-generated electron/hole pairs and restrain charge recombination to generate photo-reactive sites. Electrochemical impedance spectroscopy (EIS) revealed that A-ZP and A-ZS had low charge transfer resistance compared to their bare counterparts. This lead to considerably improved PEC performance. An unprecedented increase in IPCE values in A-ZP and A-ZS can be assigned to the decrease in band gap and thereby significant enhancement in photocurrent density. These result in to proper charge segregation and improved charge transportation. The maximum value of IPCE is 9.6% for A-ZS sample and it is also clear that ZP and ZS nanostructured film have higher IPCE values at similar to 400 nm than traditional ZnO thin film. A-ZP and A-ZS based photo-anodes have exhibited enhanced PEC performance as evident from IPCE measurements and thus can be a prospective candidate for PEC and optoelectronic applications. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.