Regulating interlayer charge transfer in MoS2 via in-situ loading of Pd-metallene to enhance piezo-catalytic degradation efficiency: Contributions of low free energy

Abstract

Molybdenum disulfide (MoS₂) is a promising piezoelectric catalytic material that has garnered considerable research attention. However, its application in the water treatment field is hindered by electron/hole recombination, leading to relatively low piezoelectric efficiency. This study proposes a strategy of establishing interlayer electron bridges by anchoring Palladium metallene (Pd-ene) with ultra-high conductivity and high longitudinal strain response into MoS₂, aiming to accelerate carrier migration. The Pd-ene/MoS₂-3 catalyst exhibited outstanding piezoelectric catalytic activity, achieving a tetracycline degradation efficiency of 96.51 % and a Cr⁶⁺ reduction efficiency of 90.45 % within 30 min. PFM and d₃₃ measurements indicated that the piezoelectric response signal and piezoelectric coefficient were 2.17 times and 6.4 times higher, respectively, compared to pure MoS₂. Electrochemical tests revealed that the improved piezoelectric performance is primarily due to enhanced transient piezoelectric current response, reaching 5.9 mA/cm². The presence of Pd-ene significantly boosts the catalyst’s performance in terms of current density, electrochemically active surface area, and impedance when compared to MoS₂ alone. Notably, the theory calculations and quantitative experiments on radicals showed a reduction in the band gap width from 2.62 eV to 1.31 eV, creating favorable conditions for lowering the system’s free energy and facilitating the formation of H₂O₂. Among them, the free energy of H₂O adsorption, dissociation to 2OH*, deprotolation to 2O* and desorption to O₂ path decreased by 5.21, 4.96, 2.64 and 4.15 eV, respectively. This study presents an innovative strategy for enhancing the piezocatalytic activity of MoS₂ and explores the application of metallene in the field of piezoelectronics.