A detailed degradation study of the
halogenated alkenes initiated
by oxidants present in the atmosphere is of utmost importance because
of its ability to release free halogen, which affects the environment
to a large extent. In this work, we have studied the hydroxyl radical
(·OH) initiated degradation of a halogenated alkene, 1,1-dichloro-2,3,3,3-tetrafluoroprop-1-ene,
CF3CFCCl2 (CFP) in the atmosphere. We
have proposed that the reaction proceeds via two ways: (i) addition
reactions to either side of the double bond, and (ii) Cl-abstraction
reactions. We have used both the Density Functional Theory (DFT) and
post-Hartree–Fock methods with triple-ζ correlation consistent
basis sets, cc-pVTZ for geometry optimization, and frequency calculation.
Thermodynamic and kinetic parameters are studied using the above-mentioned
theoretical accuracies. The potential energy surface (PES) showed
that both the addition reactions are exothermic in nature, whereas
Cl-abstraction reactions are endothermic. The kinetic and branching
ratio calculation results revealed that the addition of an ·OH
radical to double bonded carbon atoms (C1 and C2) is more dominant
than the Cl-abstraction reactions. The overall rate constant calculated
at 298 K using the M06-2X functional is found to be in closer approximation
with the experimental results than the post-Hartree–Fock, MP2
method. The atmospheric lifetime and ozone depletion potential (ODP)
of CFP are calculated as 2.48 days and 7.60 × 10–5, respectively. Finally, the photochemical ozone creation potential
(POCP) of CFP is estimated to be 6.40.
Herein, we report a systematic study of nanohybrids (NHs) of various FeÀ Co oxides anchored on to carbon matrix for highperforming oxygen electrode reactions. Fe 2.1 Co 0.9 O 4 /C NH having minor content of Co 3 + exhibited superior oxygen reduction reaction (ORR) performance than the other compositions and benchmark Pt/C. It exhibits a current density of 8.4 mA cm À 2 in 0.1 M KOH for ORR compared to the benchmark Pt/C (3.81 mA cm À 2 ). It also reveals superior stability and durability than Pt/C. It can retain 92 % of its initial current up to 7000 s. Also, the Fe 2.1 Co 0.9 O 4 /C NH delivers the best Tafel slope of 72.6 mV dec À 1 . Additionally, the Co 3 + rich Fe 0.9 Co 2.1 O 4 /C NH demonstrated superior oxygen evolution reaction (OER) performance than the Pt/C, RuO 2 and other compositions in 0.1 M KOH solution. Thus, the obtained electrocatalysts (ECs) having bimetallic active site demonstrates unique electrocatalytic properties and the carbon matrix can increase stability and thus provide additional catalytic active sites. This makes them a significant candidate for oxygen electrocatalysis.
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