Synergistic effect of pulsed-laser-deposited PbS nanoparticles on porous silicon for indoor air remediation

Abstract

This study investigates the photocatalytic performances of incorporating lead sulfide (PbS-NPs) onto porous monocrystalline silicon (PS/c-Si) structures (PbS-NPs/PS/c-Si) for volatile organic compounds (VOCs) removal from indoor air. Here the butane-2, 3-Dione (BUT: C₄H₆O₂) is chosen as pollutant model due to its presence in the cheese industry. The porous silicon (PS) layers were synthesized using the electrochemical anodization procedure on the mono-crystalline silicon (mc-Si) substrate. The deposition of PbS-NPs on the porous silicon layer was performed using the pulsed laser deposition (PLD) technique. The average size of PbS-NPs varied from 9 nm to 16 nm as the number of laser ablation pulses (NLP) increased from 500 to 10,000. The Scanning electron microscopy (SEM) analysis indicated that an increase in laser ablation pulses leads to the aggregation of the PbS-NPs. Atomic Force Microscopy measurements showed that the root means square (RMS) roughness of the PbS-NPs/PS/c-Si structure increased with NLP and reached its maximum value at NLP = 5000, which is probably due to the aggregation of PbS-NPs and the increase in NP size. The adsorption spectra indicated that the PbS nanoparticles possess an indirect optical bandgap ranging from 0.86 eV to 0.93 eV. This bandgap reflects excitonic transitions, which are strongly influenced by surface state defects, especially in smaller NPs (NLP < 2500). At the optimized PbS-NPs laser pulses (N_LP = 5000), the catalyst exhibited a high photocatalytic efficiency for BUT removal, reaching 82 %.