Holey MXene nanosheets intimately coupled with ultrathin Ni-Fe layered double hydroxides for boosted hydrogen and oxygen evolution reactions

Although Ni-Fe layered double hydroxides (LDH) are considered as efficient noble metal-free electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), their overall electrocatalytic performance still needs to be significantly enhanced to satisfy the requirements of practical water splitting systems. Herein, we demonstrate the reasonable design and controllable fabrication of holey Ti3C2Tx MXene nanosheets intimately coupled with ultrathin Ni-Fe LDHs (LDH/H-Ti3C2Tx) through a combined in situ oxidative etching and hydrothermal assembly strategy. Such a newly-developed nanoarchitecture with abundant in-plane holes not only creates a sophisticated three-dimensional (3D) ion diffusion model to shorten the diffusion path of reactants, but also exposes a large number of extra catalytically active sites as well as guarantees a high charge transfer rate, which enable to dramatically accelerate the electrochemical HER and OER kinetics. As a consequence, the resulting LDH/H-Ti3C2Tx catalyst affords exceptional HER and OER performance with low overpotentials, small Tafel plots and excellent cycling stability, far outperforming the bare Ni-Fe LDHs and Ti3C2Tx catalysts. This work is expected to open up a new avenue to the confined growth of active nanomaterials on holey MXene nanosheets and promote their applications in the energy-conversion and -storage fields.