MXene/Blue Phosphorene for Photocatalytic Overall Water Splitting Application.

MXenes, represented by the general formula Mn+1XnTx, are a class of 2D materials composed of transition metals (M), carbon or nitrogen (X), and surface functional groups (T) such as hydroxyl or oxygen. Their exceptional electrical conductivity, high surface area, good mechanical properties, stability, and low toxicity make them promising for a wide range of applications. To further enhance their properties, MXenes can be combined with other 2D materials to form vdW heterostructures. Our work focuses on the MXene/blue phosphorene (BlueP) heterostructure, where strain engineering is employed to tune its electronic and mechanical properties. By  studying the effects of biaxial and uniaxial strain, we demonstrate how strain modulates key properties such as bandgap and electronic states. The Sc2CO2//BlueP heterostructure exhibits type-II band alignment, which enhances photocatalytic performance by  efficient charge separation. Electrons migrate to the CBM of one layer, while holes remain confined to the VBM of the other, aided by a built-in electric field that reduces charge recombination. Using both empirical and DFT methods, we evaluated its potential for photocatalytic water splitting, supported by absorption spectra analysis. We  calculated the Gibbs free energy for OER and HER, and found that strain engineering improves the overpotential for catalytic activity. Our findings reveal that applying compressive strain further enhances photocatalytic efficiency.