Cobalt 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.

Cobalt acetate (Co(Ac)2)
(99.99%) and sodium tungstate (99%) were purchased from Sigma-Aldrich
(USA). Herring Testes double-stranded deoxyribonucleic acid (DNA)
with a base pair of around 50 k was also obtained from Sigma-Aldrich
(USA) and used as received. Initially, the stock solutions of DNA
was prepared by mixing (0.12 M) DNA powder in DI water and stirred
for 12 h. The solid DNA powder was uniformly dispersed upon rigorous
stirring over 12 h and resulted in a clear solution. Methanol (Qualigen)
and sodium hydroxide (Qualigen) was used as received. XRD was performed
at a scan rate of 1° min^–1 with the 2θ
range 10–90° using a Bruker X-ray powder diffractometer
(XRD) that employed Cu Kα radiation (λ = 0.154 nm). The
morphological analysis of CTOOH samples were studied using transmission
electron microscopy (TEM), (TecnaiTM G2TF20) working at an accelerating
voltage of 200 kV. Field emission scanning electron microscopy (FE-SEM)
was performed in a SUPRA 55VP Gemini Column (Carl Zeiss, Germany)
with an air lock system. Scanning electron microscopy (SEM) was performed
using a Tescan VEGA 3 SBH instrument with a BrukerEasy EDS attached
setup.