We report the synthesis of lead(II) complexes of 2-(thiophen-2-ylmethylene) hydrazine-1-carbothioamide (1) and 2-(1-(thiophen-2-yl) ethylene) hydrazine-1-carbothioamide (2), which were used as single source precursors in hexadecylamine (HDA) and oleylamine (OLA) at 190, 230, and 270°C to synthesize lead(II) sulfide nanoparticles. Optical studies by UV–vis analysis showed a general blue shift in the absorption band edge of the PbS nanoparticles (NPs) with energy bandgaps determined by Tauc’s plots ranging from 2.15 to 3.11 eV. The development of NPs with a variety of morphologies that changed with temperature and precursor type was demonstrated by morphological characterization using scanning electron microscopy and transmission electron microscopy. Cubic, rod-shaped, and nearly spherical-shaped PbS were formed. Powder X-ray diffraction (p-XRD) structural studies revealed the face-centered cubic structure of PbS nanoparticles. The elements contained in the nanoparticles were identified by energy dispersive X-ray spectroscopy (EDX). These results suggest that the size, shape, and optical properties of the synthesized PbS NPs were affected by reaction temperature, capping group, and precursor type. Under UV irradiation, the photocatalytic activity of HDA-capped PbS nanoparticles on the degradation of methylene blue dye ranged from 28.3% to 60.0%, with lead sulfide nanoparticle obtained by thermolysis of complex (1) at 230°C showing the highest photocatalytic efficiency (60.0%).