Abstract:
We report fast and complete destruction of the
dye Congo red (CR) under visible light in the
presence of Nd3+ and Er3+ doped TiO2 nanocomposites
(NCs). TiO2 NCs with general composition
TiO2[R2O3]x, {x=0.1, 0.2; R≡ Nd, Er} and
particle size 12-16 nm were synthesized through
co-precipitation/hydrolysis (CPH). A set of similar
composites was also prepared through solid
state reaction (SSR) route, which produced 31-
47 nm particles. After characterization, visible
light photocatalytic activity of all the samples
was recorded for the degradation of CR. NCs
with molar concentration x=0.2 of both doping
types produced close to 100% degradation in 180
min. The apparent rate constant (kobs) was found
to be 2.91×10–2 min–1 and 2.36×10–2 min–1, for
these Nd3+ and Er3+ doped NCs, respectively. The
other NCs with x=0.1, also showed significant
degradation of CR, but the samples prepared
through SSR performed worse. The excellent
degradation obtained with the NCs may be
attributed to their small particle size. Moreover,
the doping of Nd3+ and Er3+ ions further supported
the photocatalysis through formation of intermediate
energy levels within the band gap of
TiO2. These new levels not only acted as electron
traps for efficient suppression of the undesired
e–/h+ recombination, but also facilitated to a certain
extent the absorption of visible irradiation.
