53 research outputs found
Seasonal march of surface pressure gradients across India and the southwest monsoon
No full textIt is well known that the seasonal weather features of Indian sub-continent are associated with corresponding changes in the pressure gradients across the country
Ce-Doped CuMgAl Oxide as a Redox Couple Mediated Catalyst for Visible Light Aided Photooxidation of Organic Pollutants
No full textCe
doped CuMgAl (10:40:50)-mixed metal oxides with different Ce
contents (0.5–2.0 wt %) were synthesized by a simple coprecipitation
method followed by doping with cerium. Then, their structural, optical,
and morphological properties were characterized. The results revealed
that the surface areas of the samples are very high (∼138 m2/g), which is an important property of a photocatalyst. All
the doped samples exhibited enhanced photocatalytic activity compared
to the undoped sample for degradation of a model organic pollutant,
2,4-dichlorophenol (2,4-DCP). The amount of Ce doping in the material
played an important role in the photocatalysis. Among the prepared
samples, 1.0 wt % Ce doped sample exhibited highest photocatalytic
activity due to lowest recombination of photogenerated electron–holes.
The developed Ce4+/Ce3+ redox couple is a special
feature of the catalytic design, which mainly facilitates separation
of photogenerated electrons and holes. The catalytic steps on conduction
band and valence band of the photocatalyst are favorable to form Ce4+/Ce3+ redox couples in continuous cycles and,
hence, accelerate the photocatalytic process effectively. Moreover,
activity of the catalyst was investigated under various light irradiations,
such as UV, visible, and UV–vis light. The rate of the photodegradation
is found to be 3.7 times and almost 5 times higher by using the 1.0
wt % Ce doped sample compared to the undoped sample under visible
light and UV–vis light irradiation, respectively. A possible
mechanism of photocatalysis and pathways of degradation of 2,4-DCP
are also discussed
Strategic Design of a WO3/PdOxCarbon Shell Composite Photocatalyst: Visible Light-Mediated Selective Hydrogenation of 5Hydroxymethylfurfural
No full textThe development of visible light-assisted
heterogeneous selective
hydrogenation by utilizing solvents as a H2 source is a
sustainable and energy-saving approach. Here, we have synthesized
an efficient WO3/PdOx-carbon
shell composite photocatalyst via the solution combustion method (SCM).
The catalyst showed excellent activity for 5-hydroxymethylfurfural
(HMF) hydrogenation in H2O/MeOH (3:1) under visible light
(λ ≥ 420 nm) without the use of a pressurized external
hydrogen support. The primary product was identified as 5-bis(hydroxymethyl)furan
(BHMF) with a yield of 79.2%, which is regarded as a valuable feedstock
for polymer industries. The minor hydrogenolysis product 5-methylfurfuryl
alcohol (MFA) was also observed in proton NMR with a yield <20%.
Our findings reveal that conversion efficiency (>95%) and selectivity
(86.9%) increase drastically along with the pH range of the reaction
medium, i.e., 7.5–8.2. The photocatalyst was embedded with
both quantum-sized (0.6%) Pd particles (<5 nm) and PdO. After a
series of experiments, we found that the uniform dimension (10 nm)
of carbon shell benefits the stability of Pd particles (catalytic
active site) and enhances charge carrier mobility. The photocatalyst
is durable and reusable for up to more than six cycles without any
significant loss in its activity. The progress of the reaction and
key reactive species (•OH) were systematically investigated
by proton NMR kinetic studies and electron paramagnetic resonance
(EPR) spectroscopy. The possible reaction pathway was investigated
and explored. These studies may contribute to serving as a cost-effective
alternative method for a hydrogenating agent at an ambient condition
without the use of a pressurized external hydrogen/temperature support
under visible light
Riboflavin-Immobilized CeO<sub>2</sub>–RGO Nanohybrid as a Potential Photoredox Catalyst for Enhanced Removal of Organic Pollutants under Visible Light
No full textWe report a facile immobilization of riboflavin (RF)
over in situ
synthesized CeO2–reduced graphene oxide (RGO) nanohybrid
surface synthesized through a simple wet-chemical approach for photocatalytic
degradation of organic pollutants under visible light (λ ≥
420 nm). The hybrid containing 3% w/w RGO shows an excellent photocatalytic
activity under visible light. The UV–visible diffuse reflectance
spectra, photoluminescence (PL) analysis, and transient photocurrent
measurements corroborate that the hybrid RF@CeO2–RGO
significantly absorbs visible light and exhibits lower recombination
of charge carriers in comparison to RF@CeO2. The catalyst,
RF@CeO2–RGO, offers enhancement in photocatalytic
rate, i.e., 2.8-fold increase for methyl orange (MO) and 3.5-fold
for p-nitrotoluene (PNT) in comparison to RF@CeO2 under visible light (2 h). This enhancement could be attributed
to the synergistic effect among CeO2, RF (broadens visible
light absorption region), and RGO (an electron-shuttling agent), which
lead to an efficient separation of charge carriers. Consequently,
the hybrid photocatalyst shows higher rate constant values, 2.31 ×
10–2 and 2.00 × 10–2 min–1 for PNT and MO dye, respectively. The catalytic studies
were monitored using UV–vis spectroscopy, high-performance
liquid chromatography–photodiode array (HPLC–PDA), and
gas chromatography–mass spectrometry (GC–MS) techniques.
From the radical trapping experiments, the involvement of both superoxide
and hydroxyl radicals was inferred. The present study provides more
insights into the photochemical activity of metal-free sensitizer,
RF, on metal oxide/hybrids (CeO2 and CeO2–RGO
hybrids) and its viability for the remediation of water pollutants
Controlled Synthesis of Hierarchical Porous Ag3PO4 Microspheres through Natural Template for Photocatalytic Applications
No full textThe talk presented at 29th Annual General Meeting Of Materials Research Society Of India And National Symposium On Advances In Functional And Exotic Materials
Ru(ii)-Metal complex immobilized mesoporous SBA-15 hybrid for visible light induced photooxidation of chlorophenolic compounds in aqueous medium
No full textBoosted Charge Transfer Efficacy of an All‐Solid‐State Z‐Scheme BiOI‐CD‐CdS Photocatalyst for Enhanced Degradation of 4‐Nitrophenol and Oxidation of Benzyl Alcohol under Visible Light**
No full textMetal-free-photocatalytic reduction of 4-nitrophenol by resin-supported dye under the visible irradiation
No full textSustainable Design of Hierarchically Porous Ag<sub>3</sub>PO<sub>4</sub> Microspheres through a Novel Natural Template and Their Superior Photooxidative Capacity
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