The development and
application of trimetallic nanoparticles continues
to accelerate rapidly as a result of advances in materials design,
synthetic control, and reaction characterization. Following the technological
successes of multicomponent materials in automotive exhausts and photovoltaics,
synergistic effects are now accessible through the careful preparation
of multielement particles, presenting exciting opportunities in the
field of catalysis. In this review, we explore the methods currently
used in the design, synthesis, analysis, and application of trimetallic
nanoparticles across both the experimental and computational realms
and provide a critical perspective on the emergent field of trimetallic
nanocatalysts. Trimetallic nanoparticles are typically supported on
high-surface-area metal oxides for catalytic applications, synthesized
via
preparative conditions that are comparable to those
applied for mono- and bimetallic nanoparticles. However, controlled
elemental segregation and subsequent characterization remain challenging
because of the heterogeneous nature of the systems. The multielement
composition exhibits beneficial synergy for important oxidation, dehydrogenation,
and hydrogenation reactions; in some cases, this is realized through
higher selectivity, while activity improvements are also observed.
However, challenges related to identifying and harnessing influential
characteristics for maximum productivity remain. Computation provides
support for the experimental endeavors, for example in electrocatalysis,
and a clear need is identified for the marriage of simulation, with
respect to both combinatorial element screening and optimal reaction
design, to experiment in order to maximize productivity from this
nascent field. Clear challenges remain with respect to identifying,
making, and applying trimetallic catalysts efficiently, but the foundations
are now visible, and the outlook is strong for this exciting chemical
field.
The rise in atmospheric
CO
2
concentration and the concomitant
rise in global surface temperature have prompted massive research
effort in designing catalytic routes to utilize CO
2
as
a feedstock. Prime among these is the hydrogenation of CO
2
to make methanol, which is a key commodity chemical intermediate,
a hydrogen storage molecule, and a possible future fuel for transport
sectors that cannot be electrified. Pd/ZnO has been identified as
an effective candidate as a catalyst for this reaction, yet there
has been no attempt to gain a fundamental understanding of how this
catalyst works and more importantly to establish specific design criteria
for CO
2
hydrogenation catalysts. Here, we show that Pd/ZnO
catalysts have the same metal particle composition, irrespective of
the different synthesis procedures and types of ZnO used here. We
demonstrate that all of these Pd/ZnO catalysts exhibit the same activity
trend. In all cases, the β-PdZn 1:1 alloy is produced and dictates
the catalysis. This conclusion is further supported by the relationship
between conversion and selectivity and their small variation with
ZnO surface area in the range 6–80 m
2
g
–1
. Without alloying with Zn, Pd is a reverse water-gas shift catalyst
and when supported on alumina and silica is much less active for CO
2
conversion to methanol than on ZnO. Our approach is applicable
to the discovery and design of improved catalysts for CO
2
hydrogenation and will aid future catalyst discovery.
A number of Pd based materials have been synthesised and evaluated as catalysts for the conversion of carbon dioxide and hydrogen to methanol, a useful platform chemical and hydrogen storage...
A correlative electron microscopy method is introduced to statistically composition distributions among particles in nanoalloy materials, a parameter that is largely overlooked before.
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