The development of highly active
and durable catalysts for electrochemical
reduction of CO2 (ERC) to CH4 in aqueous media
is an efficient and environmentally friendly solution to address global
problems in energy and sustainability. In this work, an electrocatalyst
consisting of single Zn atoms supported on microporous N-doped carbon
was designed to enable multielectron transfer for catalyzing ERC to
CH4 in 1 M KHCO3 solution. This catalyst exhibits
a high Faradaic efficiency (FE) of 85%, a partial current density
of −31.8 mA cm–2 at a potential of −1.8
V versus saturated calomel electrode, and remarkable stability, with
neither an obvious current drop nor large FE fluctuation observed
during 35 h of ERC, indicating a far superior performance than that
of dominant Cu-based catalysts for ERC to CH4. Theoretical
calculations reveal that single Zn atoms largely block CO generation
and instead facilitate the production of CH4.
All-solid-state
lithium-ion batteries (SSLIBs) are promising candidates
to meet the requirement of electric vehicles due to the intrinsic
safety characteristics and high theoretical energy density. A stable
cathodic interface is critical for maximizing the performance of SSLIBs.
In this study, operando X-ray absorption near-edge spectroscopy (XANES)
combined with transmission electron microscopy (TEM) and electron
energy loss spectroscopy (EELS) is employed to investigate the interfacial
behavior between the Ni-rich layered cathodes and sulfide solid-state
electrolyte. The study demonstrates a metastable intermediate state
of sulfide electrolyte at high voltage and parasitic reactions with
cathodes during the charge/discharge process, which leads to the surface
structural reconstruction of Ni-rich cathodes. Constructing a uniform
interlayer by atomic layer deposition (ALD) is also employed in this
study to further investigate the cathodic interface stability. These
results provide new insight into the cathodic interface reaction mechanism
and highlight the importance of advanced operando characterizations
for SSLIBs.
The electrochemical reduction of N 2 to NH 3 is emerging as ap romising alternative for sustainable and distributed production of NH 3 .H owever,t he development has been impeded by difficulties in N 2 adsorption, protonation of *NN,a nd inhibition of competing hydrogen evolution. To address the issues,w ed esign ac atalyst with diatomic Pd-Cu sites on N-doped carbon by modulation of single-atom Pd sites with Cu. The introduction of Cu not only shifts the partial density of states of Pd toward the Fermi level but also promotes the d-2p*c oupling between Pd and adsorbed N 2 ,l eading to enhanced chemisorption and activated protonation of N 2 ,and suppressed hydrogen evolution. As ar esult, the catalyst achieves ah igh Faradaic efficiency of 24.8 AE 0.8 %a nd ad esirable NH 3 yield rate of 69.2 AE 2.5 mgh À1 mg cat. À1 ,f ar outperforming the individual single-atom Pd catalyst. This work paves ap athway of engineering single-atom-based electrocatalysts for enhanced ammonia electrosynthesis.
Sulfide-based
solid-state electrolytes (SSEs) are considered a
key part in the realization of high-performance all solid-state lithium-ion
batteries (ASSLIBs). However, the incompatibility between conductive
additives and sulfide-based SSEs in the cathode composite challenges
the stable delivery of high-rate capability. Herein, a poly(3,4-ethylenedioxythiophene)
(PEDOT) modification is designed as a semiconductive additive for
cathode composites (cathode/SSE/carbon) to realize the high performance.
The modified ASSLIB demonstrates a competitive rate capacity of over
100 mAh g–1 at 1C, which is 10
times greater than that of the bare cathode. Detailed surface chemical
and structural evolutions at the cathodic interface indicate the PEDOT
modification not only significantly suppresses the side reactions
but also realizes effective electron transfer at the cathode/SSE/carbon
three-phase interface. Introducing a controllable semiconductive additive
for the cathode composites in this study offers a promising design
to realize the high-rate performance and overcome long-term challenges
in the application of conductive additives in sulfide-based ASSLIBs.
Rationally tuning the local structures
of single-atomic active
sites for the electrocatalytic N2 reduction reaction (NRR)
remains an urgent but worthwhile research topic. Herein, we accomplish
the local modulation of single-atomic Mn sites and construct single
Mn–O3N1 sites anchored on porous carbon
(Mn–O3N1/PC) by delicately controlling
the Mn–O bonding conditions. The constructed structures are
confirmed via the combination of atomic-scale imaging, Raman spectroscopy,
synchrotron radiation-based soft and hard X-ray absorption spectroscopies,
and X-ray photoelectron spectroscopy. The Mn–O3N1/PC catalyst yields an NH3 yield rate of 66.41
μg h–1 mgcat.
–1 (corresponding to 1.56 mg h–1 mgMn
–1) at −0.35 V versus reversible hydrogen electrode,
which is about four times that on the control Mn–N4/PC catalyst. The enhanced NRR performance is ascribed to its unique
geometry and electronic structures, which not only facilitate the
adsorption and activation of the N2 molecule but also lower
the free energy change of the potential-determining step.
Single-atom catalysts (SACs) have attracted significant attention due to their superior catalytic activity and selectivity. However, the nature of active sites of SACs under realistic reaction conditions is ambiguous. In this work, high loading Pt single atoms on graphitic carbon nitride (g-C 3 N 4)-derived N-doped carbon nanosheets (Pt 1 /NCNS) is achieved through atomic layer deposition. Operando X-ray absorption spectroscopy (XAS) is performed on Pt single atoms and nanoparticles (NPs) in both the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). The operando results indicate that the total unoccupied density of states of Pt 5d orbitals of Pt 1 atoms is higher than that of Pt NPs under HER condition, and that a stable Pt oxide is formed during ORR on Pt 1 /NCNS, which may suppress the adsorption and activation of O 2. This work unveils the nature of Pt single atoms under realistic HER and ORR conditions, providing a deeper understanding for designing advanced SACs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.