The products of thermal
decomposition of iron nitrate nonahydrate
doped into poly(vinylidene difluoride) are examined using Mössbauer
spectroscopy. Very little of the expected nitrogen dioxide product
is observed, which is attributed to Fe3+ catalysis of the
decomposition of NO2. The active site of the catalysis
is shown to be Fe(OH)3 in the polymer matrix, which is,
unexpectedly, reduced to Fe(OH)2. Thermodynamic calculations
show that the reduction of Fe3+ is exergonic at sufficiently
high temperatures. A reaction sequence, including a catalytic cycle
for decomposition of NO2, is proposed that accounts for
the observed reaction products. The role of the polymer matrix is
proposed to inhibit transport of gas-phase products, which allows
them to interact with Fe(OH)3 doped in the polymer.