We present a comprehensive
mechanistic study on the highly tunable
selectivity over In
x
/ZrO2 catalysts
in CO2 hydrogenation. By variation of the indium loading
between 0.1 and 5 wt %, either an admirable selectivity to methanol
of 70–80% or up to 80% selectivity to CO could be obtained
in the temperature range of 250–280 °C. It is shown that
the shift in the product spectrum is related to the synergy between
indium species and the zirconia substrate through variable interfacial
structures. Zirconia-modulated crystalline In2O3, which prevails for indium loadings between 2.5 and 5 wt %, could
enhance stepwise hydrogenation of *HCOO, leading to *H3CO and finally methanol due to the suitable bonding strengths of
*HCOO and *H3CO. Regarding CO, evidence has been provided
that the synergistic effect between adjacent indium and zirconia sites
is indispensable for the entire catalytic cycle. *HCOO is formed at
the indium–zirconia interfaces and decomposes to CO subsequently.
Highly dispersed InO
x
dominating for loadings
below 0.5 wt % features an enormous indium–zirconia interface
and suppresses hydrogenation ability for *HCOO, thus favoring the
generation of CO. The study provides fundamental insights into the
mechanism of CO2 conversion and reaction pathway tuning
over oxide catalytic systems.
Puzzlingly logical: The characteristic fluorescence of Hg2+‐selective OFF‐ON and Cu2+‐selective ON‐OFF operations can be monitored and controlled reversibly by the sequence and ratio of Hg2+ and Cu2+ inputs. These inputs have been used to construct a molecular keyboard that is capable of crossword puzzles and logic memory (see picture).
The
carbon dioxide (CO2) methanation reaction not only
provides a solution for mitigating the excessive carbon dioxide emissions
but also can potentially be employed for the storage and transportation
of low-grade energies. A supported nickel-based catalyst is the most
promising candidate for the CO2 methanation reaction. Additionally,
understanding the role of the support is essential for the rational
design of nickel-based CO2 methanation catalysts. Herein,
we elaborated on the effect of the support on the catalyst structure,
CO2 adsorption, CO2 activation, methanation
mechanism, and deactivation process. Future directions are suggested
to elucidate the fundamental aspects of this catalytic system, including
the formation mechanism of preferentially exposed facets, the nature
of strong metal–support interactions, the balance between support
reducibility and basicity, and the CO2 methanation pathways
over nickel-based catalysts with various supports.
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