Substitutional electronegative element defects-induced modification of silicene's electronic structures as high-performance cathode material for water splitting

The growing global energy demands, and environmental concerns underscore the need for innovative green and sustainable energy conversion technologies. Water splitting, an advanced method for green hydrogen production, offers exceptional energy density with zero carbon emissions, and can significantly alleviate environmental pollution and crisis. This study explores the modification of silicene's electronic structure through substitutional defects involving electronegative elements (P, Se, S, and C) to enhance its efficacy as a cathode material for the hydrogen evolution reaction (HER). Density functional theory (DFT) simulations reveal that defect-induced modifications significantly alter the electronic structure of silicene, optimizing active sites. Among the various configurations, SiC₃-silicene emerges as a superior catalyst, exhibiting an unprecedented Gibbs free energy (ΔG_H) of 0.008 eV for HER, surpassing the performance of traditional platinum-based catalysts. Furthermore, SiC₃-silicene demonstrates a minimal overpotential of 172 mV at current densities of 500 mA/cm², affirming its potential for industrial-scale applications. A comprehensive charge transfer analysis shows that the incorporation of electronegative dopants induces substantial charge redistribution, markedly increasing charge concentration at the active sites. This enhanced charge transfer plays a pivotal role in stabilizing hydrogen adsorption, thereby improving catalytic efficiency. Additionally, the structural stability of doped silicene confirms that the SiC₃-silicene configuration maintains robust structural integrity, which is essential for practical deployment. This simulation-based study introduces SiC₃-silicene as a novel, high-performance cathode material for sustainable hydrogen production, paving the way for its practical implementation in sustainable energy systems.