Elemental copper

For the mechanochemical synthesis of the CuFeS₂/TiO₂ nanocomposite, we used mechanochemically prepared CuFeS₂, which was synthesized from elemental copper (99.7%, Aldrich, Germany), iron (extra pure, Merck, Germany), sulphur (99%, Ites, Slovakia) and commercially available TiO₂ P25 powder (Degussa, Netherland) (75% anatase and 25% rutile).

CuInS₂/ZnS nanocrystals(in molar ratio 1:4 chosen on the basis of results previously published in papers [28 (link),29 (link)] for similar nanocrystals) were prepared by co-milling of CuInS₂, which was prepared by milling elemental copper (99.7%, Aldrich, Germany), indium (99.99%, Aldrich, Germany) and sulphur (99%, Ites, Slovakia) according to the procedure described in previous study [40 (link)] and precursors for preparation of ZnS according to the procedures described in papers [56 (link),57 (link)]. Precursors for ZnS were zinc acetate dihydrate (99%, Ites, Slovakia) and sodium sulphide nonahydrate (98%, Acros Organics, USA). Preparation of the CuInS₂/ZnS nanocrystals is depicted in Figure 8 and can be described by the following reactions:

Co-milling was performed in a planetary mill Pulverisette 6 (Fritsch, Germany) in an argon atmosphere for 30 min. A 250 mL tungsten carbide milling chamber with 50 tungsten carbide balls, 10 mm in diameter was used. Rotational speed of the planet carrier was 500 rpm. After the synthesis, the side product of reaction (2), sodium acetate, was removed by washing with distilled water. After vacuum drying (70 °C, 180 min), a solid phase of CuInS₂/ZnS nanocomposite was obtained.