Designing hierarchical nanostructures of earth-abundant electrocatalysts for enhanced overall water splitting performance is of great significance. Herein, Mo-doped Co(OH)(2) hierarchical nanotubes (Mo-Co(OH)(2) HNTs) assembled by cross-linked porous nanosheets are designed and synthesized through a sacrificial template strategy. Benefiting from the hierarchical structures based on porous nanosheets with void interior as well as modified electronic structure of higher intensity of Co3+ species by Mo6+ doping, the Mo-Co(OH)(2) HNTs demonstrate superior electrocatalytic performance, achieving an current density of 10 mA cm(-2) at the low overpotentials of 218 mV and 125 mV for oxygen and hydrogen evolution reactions, respectively. Furthermore, an overall water splitting cell was assembled with the Mo-Co(OH)(2) electrocatalyst as both the anode and cathode materials, which exhibits a driving voltage of as low as 1.62 V. The facile strategy presented in this work can be extended to the construction of various hollow/porous nanostructures with effective heteroatom doping to achieve low-cost, bifunctional and high-performance electrocatalysts for overall water splitting. (C) 2019 Elsevier Inc. All rights reserved.