The Journal of Physical Chemistry Letters,
Journal Year:
2025,
Volume and Issue:
unknown, P. 3847 - 3855
Published: April 9, 2025
Photocatalytic
oxidative
coupling
of
methane
(OCM)
is
a
promising
sustainable
technology
for
chemical
and
fuel
synthesis,
but
current
photocatalysts
suffer
from
limited
activity
selectivity.
Here,
we
report
highly
active
Ag/TiO2
catalyst
OCM
in
flow
reactor,
achieving
C2
hydrocarbon
production
rate
1.9
mmol
g-1
h-1
selectivity
up
to
92%
with
enhanced
stability
exceeding
150
h.
This
performance
surpasses
that
most
reported
semiconductor-based
photocatalysts.
The
attributed
synergistic
effect
between
situ
photogenerated
Ti3+
Ag
on
TiO2,
where
acts
as
hole
trap
promoting
transfer
C-H
activation,
serves
an
electron
acceptor
catalytic
center
accelerate
C-C
coupling.
These
findings
not
only
provide
valuable
mechanistic
insights
into
photocatalytic
also
demonstrate
the
utility
situ/operando
techniques
establishing
structure-activity
relation
catalysts
"at
work".
Photocatalytic
oxidation
of
methane
(CH4)
to
high
value-added
liquid
oxygenates
with
oxygen
(O2)
as
an
oxidant
has
long
been
a
promising
process.
In
addition
the
activation
CH4,
selective
reduction
O2
hydroperoxyl
(·OOH)
is
also
crucial
factor
in
determining
efficiency
and
selectivity
overall
reaction.
thermal
catalysis,
strong
interactions
between
vacancies
(OVs)
on
catalyst
surface
are
widely
adopted
means
enhancing
activation.
However,
reports
this
phenomenon
limited
photocatalysis;
attributable
fact
that
dependent
upon
its
reaction
photogenerated
electrons
(e-).
For
majority
photocatalysts,
transfer
e-
metal
cocatalysts
results
spatial
separation
from
OVs.
Therefore,
intrinsic
affinity
OVs
not
fully
exploited.
study,
we
discovered
H2
treatment
at
elevated
temperatures
ZIF-8-derived
ZnO
led
formation
OV-enriched
amorphous
layer
surface.
After
introduction
Ag
cocatalyst,
as-prepared
Agx-OVs/ZnO
exhibited
unconventional
carrier
direction,
whereby
holes
(h+)
transferred
Ag,
respectively.
As
result,
preferential
adsorption
sites
can
be
spatially
combined
together
thus
drive
realize
efficient
directed
generation
·OOH.
parallel,
h+
weakens
capability
avoids
overoxidation
while
ensuring
CH4
The
optimized
defect-rich
Ag0.5-OVs/ZnO-z
photocatalyst
reaches
oxygenate
yield
10148
μmol
gcat-1
h-1
95%
TOF
2.4
×
106
gAg-1
h-1.
This
work
sheds
new
light
design
photocatalytic
catalysts
via
manipulation
direction.
