Modification and Potential Applications of Organic–Inorganic Non-Siliceous Hybrid Materials - Mesoporous Organic-Inorganic Non-Siliceous Hybrid Materials - page 90

temperature range. In fact, the achieved ˃ values of 1 10 − 2 S cm − 1 at 150 °C
and ˃ = 3 10 − 3 S cm − 1 under ambient conditions not only beat those of any
other MOF-based compounds but are among the highest values reported to date
for proton-conducting materials. The confirmed framework and chemical stability
at elevated temperatures make such materials promising for automobile fuel cell
PEM applications.
Recently, it was showed that porous MOFs could perform as outstanding tem-
plates and/or precursors to fabricate porous carbons and related nanostructured
functional materials based on their high surface areas, controllable structures,
and abundant metal/organic species in their scaffolds [ 72 , 82 ]. ZIF-7, as another
member of ZIFs, was employed as a self-sacrificed precursor with environmen-
tally friendly glucose as an additional carbon source to produce nitrogen-doped
porous carbon (Fig. 5.13 ) [ 73 ]. The addition of the environmentally friendly car-
bon source glucose not only improves the graphitization degree of samples, but
also favors removal of Zn metal and zinc compound impurities from ZIF, leading
to the formation of metal-free in situ nitrogen-doped porous carbons. Compared to
other porous carbons, the Carbon-L (the sample was derived from glucose/ZIF-7
composites that were synthesized under liquid condition) exhibits not only much
higher electrocatalytic activity, which is close to that of commercial 20 % Pt/C,
but also better stability and increased tolerance to the methanol crossover effects,
which is superior to the 20 % Pt/C catalyst. Results indicate that both high electri-
cal conductivity and the content of pyridinic N of the prepared Carbon-L play a
key role in electrocatalytic activity for ORR.
Pt containing MOF-253 was synthesized and subsequently subjected to pyro-
lytic carbonization under non-reactive gas atmosphere [ 74 ]. Upon pyrolysis, Pt
nanoparticles embedded in electronically conductive carbon media were produced.
Fig. 5.13 ZIF-7/glucose composite-derived nitrogen-doped porous carbons as metal-free
electrocatalysts for ORR exhibiting excellent electrocatalytic activity and operation stability.
Reprinted with permission from Ref. [ 73 ]. Copyright 2013, Royal Society of Chemistry