Optimization of reaction parameters in hydrothermal synthesis: a strategy towards the formation of CuS hexagonal plates

Abstract

BackgroundFor decades, copper sulphide has been renowned as the superior optical and semiconductor materials. Its potential applications can be ranged from solar cells, lithium-ion batteries, sensors, and catalyst systems. The synthesis methodologies of copper sulphide with different controlled morphology have been widely explored in the literature. Nevertheless, the understanding on the formation chemistry of CuS is still limited. The ultimate approach undertaking in this article is to investigate the formation of CuS hexagonal plates via the optimization of reaction parameters in hydrothermal reaction between copper (II) nitrate and sodium thiosulphate without appending any assistant agent.ResultsCovellite (CuS) hexagonal plates were formed at copper ion: thiosulphate ion (normalCu2+:S2O32−) mole ratio of 1:2 under hydrothermal treatment of 155°C for 12 hours. For synthesis conducted at reaction temperature lower than 155°C, copper sulphate (CuSO4), krohnite (NaCu2(SO4)(H2O)2] and cyclooctasulphur (S8) were present as main impurities with covellite (CuS). When normalCu2+:S2O32− mole ratio was varied to 1: 1 and 1: 1.5, phase pure plate-like natrochalcite [NaCu2(SO4)(H2O)] and digenite (Cu9S5) were produced respectively. Meanwhile, mixed phases of covellite (CuS) and cyclooctasulphur (S8) were both identified when normalCu2+:S2O32− mole ratio was varied to 1: 2.5, 1: 3 and 1: 5 as well as when reaction time was shortened to 1 hour.ConclusionsCuS hexagonal plates with a mean edge length of 1 μm, thickness of 100 nm and average crystallite size of approximately (45 ± 2) nm (Scherrer estimation) were successfully synthesized via assisting agent- free hydrothermal method. Under a suitable normalCu2+:S2O32− mole ratio, we evidenced that the formation of covellite (CuS) is feasible regardless of the reaction temperature applied. However, a series of impurities were attested with CuS if reaction temperature was not elevated high enough for the additional crystallite phase decomposition. It was also identified that normalCu2+:S2O32− mole ratio plays a vital role in controlling the amount of cyclooctasulphur (S8) in the final powder obtained. Finally, reaction time was recognized as an important parameter in impurity decomposition as well as increasing the crystallite size and crystallinity of the CuS hexagonal plates formed.

Copper vacancy activated plasmonic Cu3−xSnS4 for highly efficient photocatalytic hydrogen generation: Broad solar absorption, efficient charge separation and decreased HER overpotential

“…Moreover, one can also clearly observe many vacancy defects in the nanosheets. Figures 2(c From the XRD patterns and SEM images, one can find that the intermediate product, CuS, was produced initially, which then reacted with Sn 4+ , S 2− , and Cu + (generated by the reduction of Cu 2+ by ethanol) to form kuramite phase of Cu3SnS4, which is consistent with the previous reports [35][36][37][38][39].…”

Nanostructured copper sulfides: synthesis, properties and applications

“…Accordingly, the synthesis of copper sulfides was successfully achieved in the form of nanoparticles, nanorods, nanowires or nanotubes by this approach. 31,[54][55][56][57][58][59][60][61] The application of stabilizing/capping agents has also been extensively employed in order to stabilize the narrow size distribution in 0D and specific high-energy surfaces in 1D and 2D nanostructures of copper sulfide. Du et al 31 synthesized single-crystalline, hexagonal covellite (CuS) nanoplatelets (dia: 26 nm, thickness: 8 nm) by solvothermal method in the presence of hexadecylamine and toluene as capping agent and solvent, respectively.…”

Shelling with MoS2: Functional CuS@MoS2 hybrids as electrocatalysts for the oxygen reduction and hydrogen evolution reactions

“…Table S1 summarizes the effect of thiomolybdate concentration in the reaction mixture on the products homogeneity, where a concentration of 0.30 mg•L -1 (Figure 1c) provided the conditions to obtain well-wrapped core-shell structures with negligible free standing MoS2 (< 5%). Powder XRD patterns (Figure 2a) contain peaks of both MoS2 and CuS (covellite), [45,46] without evidence of metallic Cu. The Cu cores were sulfidized to CuS, potentially due to the release of sulfur during the decomposition of thiomolybdate and the formation of MoS2.…”