Hello,

I am synthesizing sulfur-doped nickel sulfide (NiS) through the solvothermal method. And examining the influences of different contents of the sulfur source on the morphological changes of the NiS phases.

I have successfully synthesized the materials and are showing the flowerlike morphology in the FESEM.

However, from the XRD pattern, I am getting some interesting phenomena. The XRD results indicate that as the amount of sulfur source is increased in the synthesis, the amount of the sulfur in the resulting material decreases (i.e., from NiS2 to NiS), which is very much interesting, but I do not have any scientific concept about this phenomenon.

can anyone give an authentic scientific explanation for this effect?

For your kind information, I am briefly explaining the synthesis process:

“First, around 2.19 g NiCl2.6H2O (nickel chloride hexahydrate) was introduced to 6 ml CH3COOH (acetic acid), then the solution was put on a magnetic stirrer for around 5 min, after which 75 mL of ethanol and 1.5 g thioacetamide were added to the solution. Next, the solution was stirred for 15 min, then moved to a Teflon-lined steel autoclave for 5 h at 160 °C. Upon completion of the reaction, the autoclave was allowed to cool down naturally for several hrs. Then, the precipitate was washed several times with ethanol and DI water, and then the samples were dried in an oven at 80 ºC for 12 h.”

As, it is mentioned in the synthesis process that the thioacetamide (sulfur source) amount was varied in every experiment between 1.0, 1.5, and 2.0 g. However, based on the XRD analysis, I observed that in the first and second series of experiments, when the sulfur amount was ~1.0 g and ~1.5 g, two nickel sulfide phases, i.e., NiS2 and Ni3S4, were observed. By contrast, in the third experiment, only one phase i.e. “NiS” itself was observed when the S precursor concentration was used 2 g.

I am waiting for your positive feedback.

Thank you.

Sincerely.