Interplanar Growth of 2D Non-Van der Waals Co2N-Based Heterostructures for Efficient Overall Water Splitting

The design and synthesis of 2D heterostructured materials for water splitting are normally based on van der Waals (vdW) nanosheets, but this approach is gradually approaching a performance ceiling in terms of activity and stability. Herein, a novel heterostructured system is explored based on 2D non-vdW and conductive nanosheets. Notably, the interplanar growth of 2D non-vdW Co2N nanosheets is realized between graphene layers in the current collector of carbon fiber papers (CPs), generating an interlocking structure within CPs. The exposed surface of Co2N nanosheets possesses a high surface energy that anchors highly active CoNC, forming 2D CoNC@Co2N heterostructures outside CPs. This integrated electrocatalytic system bridged by non-vdW Co2N nanosheets presents a low overpotential of 1.52 V and an excellent stability of 280 h, which outperform most bifunctional and nonprecious-metal-based electrocatalysts in alkaline media, owing to the nature of 2D non-vdW nanosheets and the formation of strong and conductive connections among CoNC, nanosheets, and CPs.