“…In addition, advanced catalyst integration techniques must be developed in order to implement the intrinsically brittle nanoporous μ-Co 7 Mo 6 sheet as large-sized electrodes in commercial electrolyzers. By contrast, the powder form of the nanoporous intermetallic electrocatalysts, which can be spray-coated on substrates to make scalable electrodes with high material efficiency 71 , might be readily applicable for practical hydrogen production applications. Fig.…”
Intermetallic compounds formed from non-precious transition metals are promising cost-effective and robust catalysts for electrochemical hydrogen production. However, the development of monolithic nanoporous intermetallics, with ample active sites and sufficient electrocatalytic activity, remains a challenge. Here we report the fabrication of nanoporous Co7Mo6 and Fe7Mo6 intermetallic compounds via liquid metal dealloying. Along with the development of three-dimensional bicontinuous open porosity, high-temperature dealloying overcomes the kinetic energy barrier, enabling the direct formation of chemically ordered intermetallic phases. Unprecedented small characteristic lengths are observed for the nanoporous intermetallic compounds, resulting from an intermetallic effect whereby the chemical ordering during nanopore formation lowers surface diffusivity and significantly suppresses the thermal coarsening of dealloyed nanostructure. The resulting ultrafine nanoporous Co7Mo6 exhibits high catalytic activity and durability in electrochemical hydrogen evolution reactions. This study sheds light on the previously unexplored intermetallic effect in dealloying and facilitates the development of advanced intermetallic catalysts for energy applications.
“…In addition, advanced catalyst integration techniques must be developed in order to implement the intrinsically brittle nanoporous μ-Co 7 Mo 6 sheet as large-sized electrodes in commercial electrolyzers. By contrast, the powder form of the nanoporous intermetallic electrocatalysts, which can be spray-coated on substrates to make scalable electrodes with high material efficiency 71 , might be readily applicable for practical hydrogen production applications. Fig.…”
Intermetallic compounds formed from non-precious transition metals are promising cost-effective and robust catalysts for electrochemical hydrogen production. However, the development of monolithic nanoporous intermetallics, with ample active sites and sufficient electrocatalytic activity, remains a challenge. Here we report the fabrication of nanoporous Co7Mo6 and Fe7Mo6 intermetallic compounds via liquid metal dealloying. Along with the development of three-dimensional bicontinuous open porosity, high-temperature dealloying overcomes the kinetic energy barrier, enabling the direct formation of chemically ordered intermetallic phases. Unprecedented small characteristic lengths are observed for the nanoporous intermetallic compounds, resulting from an intermetallic effect whereby the chemical ordering during nanopore formation lowers surface diffusivity and significantly suppresses the thermal coarsening of dealloyed nanostructure. The resulting ultrafine nanoporous Co7Mo6 exhibits high catalytic activity and durability in electrochemical hydrogen evolution reactions. This study sheds light on the previously unexplored intermetallic effect in dealloying and facilitates the development of advanced intermetallic catalysts for energy applications.
“…The extended connected network provides beneficial properties such as high thermal and electrical conductivities. High thermal conductivity is of critical importance for process intensification in highly exothermic or endothermic reactions where the catalyst utilization becomes limited by thermal gradients; high electrical conductivity is a prerequisite for electrochemical transformations such as electrochemical CO 2 reduction. − The electrical conductivity of monolithic nanoporous metals also facilitates fundamental surface science studies that rely heavily on electron spectroscopies (e.g., Auger electron spectroscopy and X-ray photoelectron spectroscopy (XPS)). At the same time, the highly curved surfaces of nanoporous metals mimic those of metal NPs, including a high density of undercoordinated surface sites, though they exhibit many saddle points where the principal radii of curvature are of opposite sign in contrast to NPs which are exclusively convex …”
The
development of new catalyst materials for energy-efficient
chemical synthesis is critical as over 80% of industrial processes
rely on catalysts, with many of the most energy-intensive processes
specifically using heterogeneous catalysis. Catalytic performance
is a complex interplay of phenomena involving temperature, pressure,
gas composition, surface composition, and structure over multiple
length and time scales. In response to this complexity, the integrated
approach to heterogeneous dilute alloy catalysis reviewed here brings
together materials synthesis, mechanistic surface chemistry, reaction
kinetics, in situ and operando characterization, and theoretical calculations
in a coordinated effort to develop design principles to predict and
improve catalytic selectivity. Dilute alloy catalystsin which
isolated atoms or small ensembles of the minority metal on the host
metal lead to enhanced reactivity while retaining selectivityare
particularly promising as selective catalysts. Several dilute alloy
materials using Au, Ag, and Cu as the majority host element, including
more recently introduced support-free nanoporous metals and oxide-supported
nanoparticle “raspberry colloid templated (RCT)” materials,
are reviewed for selective oxidation and hydrogenation reactions.
Progress in understanding how such dilute alloy catalysts can be used
to enhance selectivity of key synthetic reactions is reviewed, including
quantitative scaling from model studies to catalytic conditions. The
dynamic evolution of catalyst structure and composition studied in
surface science and catalytic conditions and their relationship to
catalytic function are also discussed, followed by advanced characterization
and theoretical modeling that have been developed to determine the
distribution of minority metal atoms at or near the surface. The integrated
approach demonstrates the success of bridging the divide between fundamental
knowledge and design of catalytic processes in complex catalytic systems,
which can accelerate the development of new and efficient catalytic
processes.
“…LLNL would send us catalyst materials to put it into our cell; we tested it and shared the results. A recent paper was published on the work in the Journal of CO 2 Utilization with several members of the Opus 12 team as co-authors on that paper ( Qi et al., 2021 ).…”
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