Bimetallic layered double hydroxides (LDHs) have attracted substantial attention as oxygen evolution reaction (OER) catalysts. In this work, we provide a facile route to prepare Ti-doped NiCo-LDH/NF electrocatalysts with M–O–Ti (M = Ni, Co) covalent bonds via a rapid immersion method for the OER process. The experiments and density functional theory (DFT) calculations elucidate that the doping of Ti (M–O–Ti) not only exfoliates the NiCo-LDH nanosheets into spheres but also causes lattice distortion to produce more oxygen vacancies, which promotes faster exchange of intermediates and improves the electron transfer efficiency. These superior physical characters endow Ti-NiCo-LDH with an excellent overpotential of 319 mV at a current density of 50 mA cm⁻², which is markedly lower than that of NiCo-LDH (391 mV at 50 mA cm⁻²). Even at a high current density of 100 mA cm⁻², NiCo-LDH displays an overpotential of 429 mV, whereas Ti-NiCo-LDH is capable of achieving an overpotential of 353 mV. Moreover, the water electrolyzer based on the Ti-NiCo-LDH bifunctional catalyst requires a low cell voltage of 1.60 V to achieve a current density of 10 mA cm⁻², and the Ti-NiCo-LDH catalyst has been successfully applied for solar cell-driven water electrolysis and the corresponding voltage is about 1.61 V. This work offers a novel strategy to fabricate high activity NiCo-LDH with rich oxygen vacancies toward the OER process.

Aqueous zinc-ion batteries (AZIBs) are promising contenders for energy storage systems owing to their low cost and high safety. However, their practical application is hindered by uncontrolled Zn dendrites and other side reactions. Here, the three-dimensional (3D) TiO₂/Cu₂Se/C heterostructure layer derived from MXene/Cu-MOF is constructed on the Zn anode to control the deposition/dissolution behavior, which has numerous active sites, better electrical conductivity and excellent structural stability. Based on DFT calculation, the built-in electric field (BIEF) formed of TiO₂/Cu₂Se/C can enhance charge transfer and ionic diffusion to inhibit the dendrites. Furthermore, hydrophobic coating has the ability to impede the corrosion and hydrogen evolution reaction (HER) of zinc anode. Thus, TiO₂/Cu₂Se/C@Zn enable the stable and reversible Zn plating/stripping process with the outstanding lifetime of 1100 h at 2 mA·cm^–2 and even 650 h at 10 mA·cm^–2. The batteries constructed with commercial MnO₂ cathodes demonstrate the remarkable capacity (248.7 mAh·g⁻¹ at 0.1 A·g⁻¹) and impressive cycle stability (with 71.3% capacity retention after 300 cycles). As well as extending the life of AZIBs, this study is also motivating for other metal anode based secondary batteries.