New Two-Dimensional Carbon Sheet for Photocatalytic Water Splitting with High Carrier Mobility and Excellent...

Combining first-principles calculations with particle swarm optimization algorithms, we have successfully predicted an innovative two-dimensional carbon structure─the 2D Pba2 structure. This structure not only passed rigorous tests for kinetic and thermal stability but also demonstrated remarkable stability in air. This structure is originally a semiconductor with a quasi-direct band gap of 2.08 eV, but remarkably, it can be transformed into a direct band gap semiconductor through the application of suitable strain, and its band gap value can be flexibly tuned within the range of 1.85-2.34 eV. It is worth mentioning that regardless of whether strain is applied, the conduction band minimum and valence band maximum of the 2D Pba2 structure perfectly span the thermodynamic threshold for water splitting, revealing its immense potential in water splitting reactions. Moreover, the structure stands out with a carrier mobility as high as 0.87 × 10⁴ cm²·V^-1·s^-1, surpassing numerous renowned 2D materials, including MoS₂ and black phosphorene, indicating its superior performance in electron transport. In the realm of optics, 2D Pba2 also excels, possessing outstanding light absorption capabilities that provide a solid foundation for the application of optoelectronic devices. Moreover, the structure exhibits exceptional mechanical properties, including a rare negative Poisson's ratio and a significant bulk modulus, which further broaden its application prospects in nanomechanical systems. The 2D Pba2 nanosheets, with their comprehensive and exceptional properties, have emerged as ideal candidate materials for various nanodevice fields and have paved new avenues for cutting-edge applications, such as photocatalysis.