Structural, optical and photocatalytic studies of hexadecylamine-capped lead sulfide nanoparticles

Organic molecule functionalized lead sulfide hybrid system for energy storage and field dependent polarization performances

A wet chemical route is reported for synthesising organic molecule stabilized lead sulfide nanoparticles. The dielectric capacitance, energy storage performances and field-driven polarization of the organic–inorganic hybrid system are investigated in the form of a device under varying temperature and frequency conditions. The structural analysis confirmed the formation of the monoclinic phase of lead sulfide within the organic network. The band structure of lead sulfide was obtained by density functional theory calculation that supported the semiconductor nature of the material with a direct band gap of 2.27 eV. The dielectric performance of the lead sulfide originated due to the dipolar and the space charge polarization. The energy storage ability of the material was investigated under DC-bias conditions, and the device exhibited the power density values 30 W/g and 340 W/g at 100 Hz and 10 kHz, respectively. The electric field-induced polarization study exhibited a fatigue-free behaviour of the device for 103 cycles with a stable dielectric strength. The study revealed that the lead sulfide-based system has potential in energy storage applications.

Photocatalytic Degradation of Single and Binary Mixture of Brilliant Green and Rhodamine B Dyes by Zinc Sulfide Quantum Dots

We present the preparation of octadecylamine-capped ZnS quantum dots from bis(morpholinyldithiocarbamato)Zn(II) complex. The complex was thermolyzed at 130 °C in octadecylamine at different times, to study the effect of reaction time on the morphological and photocatalytic properties of the ZnS quantum dots. Powder X-ray diffraction patterns confirmed a hexagonal wurtzite crystalline phase of ZnS, while HRTEM images showed particle sizes of about 1–3 nm, and energy band gaps of 3.68 eV (ZnS–1), 3.87 eV (ZnS–2), and 4.16 eV (ZnS–3) were obtained from the Tauc plot for the ZnS nanoparticles. The as-prepared ZnS were used as photocatalysts for the degradation of brilliant green, rhodamine B, and binary dye consisting of a mixture of brilliant green-rhodamine B. The highest photocatalytic degradation efficiency of 94% was obtained from ZnS–3 with low photoluminescence intensity. The effect of catalytic dosage and pH of the dyes solution on the photocatalytic process shows that pH 8 is optimal for the degradation of brilliant green, while pH 6.5 is the best for photocatalytic degradation of rhodamine B. The degradation of the binary dyes followed the same trends. The effect of catalytic dosage shows that 1 mg mL⁻¹ of the ZnS nano-photocatalyst is the optimum dosage for the degradation of organic dyes. Reusability studies show that the ZnS quantum dots can be reused five times without a significant reduction in degradation efficiency.

Bis(4-methylpiperidine-1-carbodithioato)-lead(II) and Bis(4-benzylpiperidine-1-carbodithioato)-lead(II) as Precursors for Lead Sulphide Nano Photocatalysts for the Degradation of Rhodamine B

Bis(4-methylpiperidine-1-carbodithioato)-lead(II) and bis(4-benzylpiperidine-1-carbodithioato)-lead(II) were prepared and their molecular structures elucidated using single crystal X-ray crystallography and spectroscopic techniques. The compounds were used as precursors for the preparation of lead sulphide nano photocatalysts for the degradation of rhodamine B. The single crystal structures of the lead(II) dithiocarbamate complexes show mononuclear lead(II) compounds in which each lead(II) ion coordinates two dithiocarbamato anions in a distorted tetrahedral geometry. The compounds were thermolyzed at 180 ℃ in hexadecylamine (HDA), octadecylamine (ODA), and trioctylphosphine oxide (TOPO) to prepare HDA, ODA, and TOPO capped lead sulphide (PbS) nanoparticles. Powder X-ray diffraction (pXRD) patterns of the lead sulphide nanoparticles were indexed to the rock cubic salt crystalline phase of lead sulphide. The lead sulphide nanoparticles were used as photocatalysts for the degradation of rhodamine B with ODA-PbS1 achieving photodegradation efficiency of 45.28% after 360 min. The photostability and reusability studies of the as-prepared PbS nanoparticles were studied in four consecutive cycles, showing that the percentage degradation efficiency decreased slightly by about 0.51-1.93%. The results show that the as-prepared PbS nanoparticles are relatively photostable with a slight loss of photodegradation activities as the reusability cycles progress.