1：Experimental Design and Method Selection:

The study employs first-principles calculations based on density functional theory to investigate the photocatalytic properties of 2D Janus PtSSe. The Vienna ab initio simulation package (VASP) is used for calculations, with the generalized gradient approximation (GGA) functional for geometric structure optimization and the HSE06 functional for accurate electronic structures. The DFT-D2 functional is used to describe van der Waals interactions.

2：Sample Selection and Data Sources:

The study focuses on single-layer (SL) and double-layer (DL) PtSSe with different stacking configurations.

3：List of Experimental Equipment and Materials:

Computational tools include VASP for first-principles calculations, PHONOPY code for phonon calculations, and ab initio molecular dynamics (AIMD) simulations for thermal stability assessment.

4：Experimental Procedures and Operational Workflow:

The study involves optimizing geometric structures, calculating electronic and optical properties, assessing stability through phonon and AIMD simulations, and evaluating photocatalytic performance under strain.

5：Data Analysis Methods:

The analysis includes band structure calculations, optical absorption coefficients, carrier mobility evaluation, and alignment of band edge levels with water redox potentials.