Improving the intrinsic activity of ultrathin 2D-2D heterostructures by bridge-bonded Ni-O-Ti ligands for efficient oxygen evolution.

The integration of ultrathin two-dimensional (2D) semiconductors with other conductive 2D materials to form hybrid electrocatalysts with abundant heterointerfaces can enhance the electrocatalytic activity by facilitating interfacial charge transfer. However, the hybrid electrocatalysts with weak interfacial bonding have limited effect on the electrocatalytic performance because the intrinsic activity of interfacial sites cannot be altered by weak interfacial interactions. As a proof-of-concept, we design ultrathin 2D-2D heterostructures with bridge-bonded Ni-O-Ti ligands based on single-layered Ti3C2Tx MXene and metal hydroxides, and further reveal the structure-activity correlation between interfacial bonding and electrocatalytic oxygen evolution reaction (OER) by combining theoretical and experimental studies. Density functional theory calculations reveal the modulation of the electronic structure of interfacial metal sites after the formation of bridged interfacial Ni-O-Ti bonding. Compared with the hydrogen-bond-linked heterostructure, the ultrathin 2D-2D heterostructure with bridge-bonded Ni-O-Ti ligands shows the enhanced intrinsic activity and stability towards electrocatalytic oxygen evolution with a very low overpotential of 205 mV at 10 mA cm-2 and a long-term durability more than 110 h. This work provides a new understanding and approach for the design and development of 2D hybrid catalysts with highly efficient electrocatalytic activity.&#xD.