Strain-Induced Enhanced Performance in 2D C2N/MoS2 Heterostructures for Photocatalytic Water Splitting: A Meta-GGA Study

The development of renewable energy technologies is critical to addressing global challenges, such as climate change and ensuring energy sustainability. One promising approach is photocatalytic water splitting, which converts solar energy into hydrogen fuel. 2D materials, especially van der Waals heterostructures, have shown great potential for enhancing photocatalytic activity. In this study, we investigated the effects of vertical, uniaxial, and biaxial strain on the electronic band gap and band edge positions of the C2N/MoS2 van der Waals heterostructure through first-principles density functional theory using both Perdew-Burke-Ernzerhof (PBE) parameterization-based generalized gradient approximation (GGA) and strongly constrained and appropriately normed (SCAN) meta-GGA functional. Our results indicated that the SCAN functional provided more accurate results for band gap and band alignment, which are close to the experimental values as compared to the PBE functional. We discovered that the heterostructure exhibited a type-II band alignment, which is essential for efficient charge separation. Our calculation also established that the band edge positions straddled the water redox potential under compressive strain, suggesting its usefulness as an efficient photocatalyst to execute hydrogen/oxygen evolution reactions, whereas, for tensile uniaxial and biaxial strains, the band alignment is within the water oxidation/reduction potential. Furthermore, our study established that the meta-GGA SCAN functional yielded results similar to those of computationally expensive hybrid HSE functionals, reducing the computational cost of electronic structure calculations. Our findings provide valuable insights for designing 2D heterostructure devices with improved photocatalytic water-splitting performance.