Preparation of Mo nanopowders through electroreduction of solid MoS₂in molten KCl–NaCl

Abstract

Electrolysis of MoS2 to produce Mo nanopowders and elemental sulfur has been studied in an equimolar mixture of NaCl and KCl at 700 °C. The reduction mechanism was investigated by cyclic voltammetry (CV), potentiostatic and constant voltage electrolysis together with spectroscopic and scanning electron microscopic analyses. The reduction pathway was identified to be MoS2 → LxMoS2 (x ≤ 1, L = Na or K) → L3Mo6S8 and LMo3S3 → Mo, and the last step to format metallic Mo was found to be relatively slow in kinetics. Electrolysis at a cell voltage of 2.7 V has led to a rapid reduction of MoS2 to nodular Mo nanoparticles (50-100 nm), with the current efficiency and energy consumption being about 92% and 2.07 kW h kg(-1)-Mo, respectively.

Electrochemically Converting Liquid Cu2S‐Sb2S3 to Liquid Cu2Sb and Sulfur in Molten Salt at 730 °C

“…Nonetheless, no anodic peaks were seen in the first cycle of sulfides (Figure 2b), demonstrating all the released S 2− had moved away from the cavity at the first scan. A high speed for removal of S 2− benefited from the high solubility of S 2− in NaCl‐KCl melt (∼39 mol/L in NaCl at 712 °C) [20] . Meanwhile, the reduction peaks could be hardly seen in the following two cycles of Sb 2 S 3 , [16] Cu 2 S (Figure 2c) and Sb 2 S 3 ‐Cu 2 S (Figure 2d), reflecting the rapid kinetics of electro‐desulfurization.…”

“…A high speed for removal of S 2À benefited from the high solubility of S 2À in NaCl-KCl melt (~39 mol/L in NaCl at 712 °C). [20] Meanwhile, the reduction peaks could be hardly seen in the following two cycles of Sb 2 S 3 , [16] Cu 2 S (Figure 2c) and Sb 2 S 3 -Cu 2 S (Figure 2d), reflecting the rapid kinetics of electrodesulfurization.…”

Solubility of CaS in CaCl₂–LiCl Eutectic Melt

“…However the formation of RS x and R x M y S z phases was often reported in these studies as intermediate phase during reduction. 69,12) This strongly suggests a contribution of R as the reductant in the melt. The authors examined the molten salt electrolysis of TiS 2 13,14) and V 3 S 4 15) under the concept of calciothermic reduction as based on OS process.…”

“…The fast supply of Ca to the reaction front is another important key for industrial application, as reported in OS process. 24) Another mechanism, FFC-Cambridge process, 1) requires ionization of sulfide and S 2¹ dissolution because the sulfide at the cathode should release S 2¹ to form the metal 612) via the lower sulfides, 7,12) and that S 2¹ diffuses out from the sulfides to the CaCl 2 melt. If we apply this mechanism to titanium sulfide, their proposal can be written as,…”

Electrolytic reduction of V₃S₄ in molten CaCl₂

“…10,11) Previously, some studies have investigated the reduction of metal sul des such as MoS 2 , Cu 2 S, and CuFeS 2 by the electrolysis in molten salt. [12][13][14][15] These sul des can easily be re ned by the conventional route without electrolysis. However, vanadium sul de has a strong af nity with sulfur so that it is dif cult to remove sulfur by hydrogen.…”