Nickel acetate

Starting materials such as ascorbic acid
(C₆H₈O₆), cetyltrimethylammonium
bromide (CTAB), sodium telluride
(Na₂TeO₃), nickel acetate (Ni(CH₃CO₂)₂·2H₂O), cobalt acetate
(Co(CH₃COO)₂·4H₂O) from (Sigma-Aldrich),
and deionized water from a milli-Q-ultra pure (18.2 MΩ cm^–1) system were used. Initially, CTAB was dissolved
in 40 mL of deionized water with vigorous stirring to form a homogeneous
solution. Then C₆H₈O₆, 1.88 mmol
of Na₂TeO₃, 1.25 mmol of Ni(CH₃CO₂)₂·2H₂O, and 0.63 mmol of Co(CH₃COO)₂·4H₂O salts were added to
the above solution. Immediately, white TeO₂ precipitate
was observed. This solution mixture was stirred for nearly 30 min
with the addition of 40 mL of deionized water. The solution was transferred
to a Teflon-lined stainless-steel autoclave and maintained at 180
°C for 24 h. The final product was washed well with ethanol and
distilled water several times to remove the excess impurities. Then
it was dried to obtain the sample coded as NCT 1. Moreover, the samples
coded as NCT 2 and NCT 3 were obtained by the same process with 0.94
and 0.63 mmol of Ni(CH₃Co₂)₂·2H₂O and 0.94 and 1.25 mmol of Co(CH₃COO)₂·4H₂O, respectively. Wet chemically prepared nickel
cobalt telluride (NCT-W) is briefly discussed in the Supporting Information.