Strain-engineered PtS₂/BTe Z-scheme heterojunction for enhanced visible-light hydrogen evolution

Addressing the limitations of rapid carrier recombination and narrow spectral response in conventional photocatalysts, we propose a strain-engineered PtS₂/BTe Z-scheme heterojunction through first-principles calculations, demonstrating exceptional visible-light hydrogen evolution performance. The van der Waals structure exhibits ultrastable characteristics, evidenced by negative binding energy (-0.261 eV), stable phonon spectra, and robust molecular dynamics at 300 K. The intrinsic Z-scheme charge transfer mechanism driven by a 2.35 eV work function difference effectively reduces the electron-hole recombination rate while maintaining a strong redox capability through band edge alignment across the water splitting potential (pH = 0–7). The heterojunction shows a low hydrogen evolution barrier and high carrier mobility, outperforming conventional PtS₂-based systems. Compressive strain (-3 % to 3 %) dynamically tunes the bandgap from 0.90 eV to 1.25 eV, achieving optimal visible-light absorption (402 nm wavelength) with a peak coefficient of 2.90×10⁵cm⁻¹. Additionally, the STH efficiency reaches a high of 14.61 %. These synergistic effects—strain-responsive band structure, efficient Z-scheme dynamics, and favorable thermodynamics—establish a new paradigm for designing adaptive photocatalysts in solar fuel conversion.