Abstract:The structural and
electronic properties
of Cu
1.96
S and Ni
3
S
2
present in nickel–copper
converter matte and sulfides such as CuS, Ni
7
S
6
, NiS, Ni
3
S
4
, and NiS
2
, likely existing
as intermediates in the oxidative leaching of the matte, were investigated
using first-principles calculations. Analyses of the total and part… Show more
Recently developed solid-state catalysts can mediate carbon dioxide (CO2) electroreduction to valuable products at high rates and selectivities. However, under commercially relevant current densities of > 200 milliamperes per square centimeter (mA cm−2), catalysts often undergo particle agglomeration, active-phase change, and/or element dissolution, making the long-term operational stability a considerable challenge. Here we report an indium sulfide catalyst that is stabilized by adding zinc in the structure and shows dramatically improved stability. The obtained ZnIn2S4 catalyst can reduce CO2 to formate with 99.3% Faradaic efficiency at 300 mA cm−2 over 60 h of continuous operation without decay. By contrast, similarly synthesized indium sulfide without zinc participation deteriorates quickly under the same conditions. Combining experimental and theoretical studies, we unveil that the introduction of zinc largely enhances the covalency of In-S bonds, which “locks” sulfur—a catalytic site that can activate H2O to react with CO2, yielding HCOO* intermediates—from being dissolved during high-rate electrolysis.
Recently developed solid-state catalysts can mediate carbon dioxide (CO2) electroreduction to valuable products at high rates and selectivities. However, under commercially relevant current densities of > 200 milliamperes per square centimeter (mA cm−2), catalysts often undergo particle agglomeration, active-phase change, and/or element dissolution, making the long-term operational stability a considerable challenge. Here we report an indium sulfide catalyst that is stabilized by adding zinc in the structure and shows dramatically improved stability. The obtained ZnIn2S4 catalyst can reduce CO2 to formate with 99.3% Faradaic efficiency at 300 mA cm−2 over 60 h of continuous operation without decay. By contrast, similarly synthesized indium sulfide without zinc participation deteriorates quickly under the same conditions. Combining experimental and theoretical studies, we unveil that the introduction of zinc largely enhances the covalency of In-S bonds, which “locks” sulfur—a catalytic site that can activate H2O to react with CO2, yielding HCOO* intermediates—from being dissolved during high-rate electrolysis.
“…Furthermore, the first high peak position 41 in the PDOS for Li s orbital of Li 4 SiO 4 , is closer to the E f compared with that for Ca s orbital of Ca 2 SiO 4 , implying that the outer electron of Li atoms in Li 4 SiO 4 can be transferred away easier than Ca atoms in Ca 2 SiO 4 .…”
The Li4SiO4 (010) exhibits greater adsorption towards CO2 than the Ca2SiO4 (100) with a stronger covalent bond and more charge transfer between the surface and CO2.
“…Figure c,d clearly reveals an enhanced overlap of electron clouds between In and S atoms because indium is more likely to give electrons to reach a steady state. Simultaneously, the hybridization of the electron cloud between Sn and S becomes more pronounced than that in SnS/C, indicating that In can also provide more covalent characteristics to the Sn–S bond . The enhanced electronic coupling can be attributed to the deficient electronic structure of In [5s 2 5p 1 ].…”
Section: Resultsmentioning
confidence: 99%
“…Simultaneously, the hybridization of the electron cloud between Sn and S becomes more pronounced than that in SnS/C, indicating that In can also provide more covalent characteristics to the Sn−S bond. 42 The enhanced electronic coupling can be attributed to the deficient electronic structure of In [5s 2 5p 1 ]. As a result, the bond strength of In−S could be enhanced significantly because of the higher electronic hybridization between the In and S atoms.…”
Section: Analysis Of the Electrocatalytic Performances Bymentioning
Heteroatom
doping can facilitate intrinsic activity via the tuning
of electronic states. However, it is still rare to elucidate the role
of a specific metal sulfide electronic state and simultaneously enhance
the CO2 electroreduction reaction (CO2RR) stability.
SnS is well-known for its ability to produce HCOOH; however, its long-term
operational stability is limited by sulfur dissolution. Herein, we
propose a strategy to reinforce the S atoms via heteroatom (In) doping.
In situ Raman tests and theoretical calculations demonstrate that
In atoms with fewer valence electrons (compared with Sn) can tune
the electronic state of SnS and strengthen the S–metal bond
energy. Consequently, sulfur dissolution was inhibited, and the reaction
pathway was optimized. Further, the In-SnS/C achieves a Faradaic efficiency
of 96.6% for formate at −0.6 V vs RHE and a catalyst stability
of 50 h at a current density of ∼37 mA cm–2. This study shows that altering the electronic structure of SnS
via heteroatoms is a strategy to optimize both the activity and stability
of electrocatalysts for the CO2RR.
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