A facile, one-pot,
solvothermal synthesis of nanocrystals (NCs)
of Zn1–x
Cd
x
S (x = 0.1 (S1)–0.9 (S9)) solid solutions has been successfully carried out using
4,4′-dipyridyldisulfide (DPDS = (C5H4N)2S2)) as a new temperature-dependent in situ source of S2– ions. Powder XRD
patterns of the samples revealed gradual phase transformation from
cubic to hexagonal upon increasing the Cd content (x) in the solid solutions Zn1–x
Cd
x
S (0 ≤ x ≤
1). FESEM analyses showed almost spherical morphology of the solid
solutions, S2, S5, and S9.
HR-TEM analyses of S3 and S9 unveiled the
presence of small nanocrystals (NCs) of size 7 and 15 nm, respectively,
and highlights the discontinuity in the pattern of lattice fringes.
Optical measurements revealed that Zn1–x
Cd
x
S solid solutions exhibit precisely
tunable band structure with varying the concentration of Cd content.
Furthermore, visible-light-assisted photocatalytic investigation revealed
very good activity of the Zn0.7Cd0.3S solid
solution for water splitting with H2 generation rate of
750 μmol h–1 g–1. Interestingly,
for the first time, the water splitting activity of the Zn1–x
Cd
x
S NCs has been applied
for efficient reduction of nitroaromatic pollutants in water by utilizing
water as a source of hydrogen. Remarkably, various substituted nitroaromatics
containing both electron-donating and -withdrawing groups as well
as dinitroaromatics can be efficiently reduced to their corresponding
amines in high yield and selectivity. Also, the photocatalyst can
be recycled and reused for several cycles without significant loss
of the activity. The plausible mechanism for the reduction of nitroaromatics
in water by Zn1–x
Cd
x
S solid solution has also been studied. Herein we
demonstrate a unique approach wherein water acts as a source of reducing
agent for the visible-light-assisted photocatalytic reduction of nitroaromatic
pollutants in water by Zn1–x
Cd
x
S solid solutions.