Charge transfer and electron jumping for highly tribocatalytic H2O2 generation of silicon powder materials

Abstract

Hydrogen peroxide (H₂O₂) is a critical green chemical pivotal to numerous industries, including healthcare, energy, chemical synthesis, and environmental remediation. The production of H₂O₂ directly from earth-abundant water, especially under ambient conditions without relying on gaseous oxygen, represents a highly sustainable and potentially economical route. Triboelectric effects enable the harvesting of friction, a ubiquitous clean energy source, for conversion into electrical energy. In this study, the efficient tribocatalytic production of H₂O₂ is demonstrated at the friction interface between silicon (Si) powder and a rotating polytetrafluoroethylene (PTFE) disk, utilizing a 10% ethanol solution as the reaction medium under ambient air. The narrow bandgap of Si (1.12 eV) facilitates charge excitation under low-frequency mechanical stirring, resulting in sustained H₂O₂ generation under mild conditions. A maximum H₂O₂ concentration of ∼174.6 μmol L⁻¹ is achieved. Quenching experiments reveal that the tribocatalytic mechanism predominantly involve hydroxyl radicals (˙OH), superoxide radicals (˙O₂⁻), and electrons (e⁻) as the principal active intermediates. Subsequently, these free radicals combine to form H₂O₂ (2˙OH → H₂O₂, ˙O₂⁻ + e⁻ + 2H⁺ → 2H₂O₂). This finding demonstrates that H₂O₂ can be efficiently synthesized through a tribocatalysis pathway under ambient temperature and pressure by applying mechanical force at the interface between Si powder and a 10% ethanol solution in the presence of air. This work provides a promising strategy for the green and efficient generation of H₂O₂ via tribocatalysis.