Since controlling substrates can program the electrochemical properties, many researchers have devoted to investigate the corresponding mechanism. However, up to now, the effects of substrate (such as morphology, size, material composition) on the performance of electrochemical sensors have been mainly focused on metal platform, while the investigation about metal oxide substrate has not been reported in detail. Zinc oxide (ZnO) is a technologically important semiconducting material with large band gap energy between 3.2 and 3.4 eV at room temperature which has attracted widespread attentions. In previous reports, the nanostructured ZnO was randomly formed on graphene layers. The control of morphology or size of nanostructures is a prerequisite for the nanostructure for fabricating various types of nanocomposites. Here, we used graphene oxide (GNO) as the supporting material for constructing a series of synchronously electrochemically reduced graphene oxide and zinc oxide composites (rGNO-ZnO) with different morphologies for comparing their morphology-dependent electrochemical sensing behaviors. The experimental parameters, such as the electrodeposition potential, time, and concentration of electrolyte, would influence the composite morphology and further bring different electrochemical sensing ability. Among them, rGNO-ZnO with nanowalls morphology (noted GZNWs), obtained from the conditions of 0.1 M Zn(NO3)(2) electrolyte, -1.0 V electrodeposition potential and 30 min electrodeposition time, presented an optimal ability for DNA detection and 2, 4, 6-Trinitrotoluene (TNT) electrocatalysis. The fine nanowall structure may be able to provide more accessible sites, and the synergistic effect between rGNO and ZnO may enlarge the electrochemical activity. The electrochemical DNA sensor based on GZNWs exhibited the steepest slope with the detection range, as well as the highest sensitivity when compared with other electrodeposition potentials. In order to further explore the other electrochemical performances (for instance the electrocatalysis), the GZNWs was used to detect the nitroaromatic compound (such as 2, 4, 6-Trinitrotoluene, TNT). It had reached the aim of improving the sensitivity of their detection. (C) 2015 Elsevier Ltd. All rights reserved.