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Figure 6. a,b) Structural simulation and HAADF-STEM of Ru-N/G SACs. c) Fourier transform magnitudes of the experimental Ru K-edge extended X-ray absorption fine structure (EXAFS) spectra of the Ru-N/G and other comparative samples.Reproduced with permission. [28] Copyright 2017, American Chemical Society. d) Structural simulation of Pt-Ru dimer dispersed on NCNT. e) ΔG H* plots for different H coverages. Reproduced with permission. [95] Copyright 2019, Nature Publishing Group. f) Schematic illustration of the synthesis of NiRu 0.13 -BDC by ion-exchange method. g) The simulated charge difference between NiRu 0.13 -BDC and Ni-BDC. Yellow represents charge accumulation and blue represents charge depletion. Reproduced with permission. [96] Copyright 2021, Nature Publishing Group. h) In situ X-ray absorption near edge structure (XANES) of Ru K-edge under OER electrochemical conditions. i) Gibbs free energy diagram during OER process on Ru/CoFe-LDHs. Reproduced with permission.

Developing efficient and robust catalysts to replace Pt group metals for oxygen reduction reaction (ORR) is conducive to achieve highly efficient energy conversion. Here, we develop a general ion exchange...

Electrochemical carbon dioxide reduction reaction (CO2RR) provides a promising way to convert CO2 to chemicals. The multicarbon (C2+) products, especially ethylene, are of great interest due to their versatile industrial applications. However, selectively reducing CO2 to ethylene is still challenging as the additional energy required for the C–C coupling step results in large overpotential and many competing products. Nonetheless, mechanistic understanding of the key steps and preferred reaction pathways/conditions, as well as rational design of novel catalysts for ethylene production have been regarded as promising approaches to achieving the highly efficient and selective CO2RR. In this review, we first illustrate the key steps for CO2RR to ethylene (e.g., CO2 adsorption/activation, formation of *CO intermediate, C–C coupling step), offering mechanistic understanding of CO2RR conversion to ethylene. Then the alternative reaction pathways and conditions for the formation of ethylene and competitive products (C1 and other C2+ products) are investigated, guiding the further design and development of preferred conditions for ethylene generation. Engineering strategies of Cu-based catalysts for CO2RR-ethylene are further summarized, and the correlations of reaction mechanism/pathways, engineering strategies and selectivity are elaborated. Finally, major challenges and perspectives in the research area of CO2RR are proposed for future development and practical applications.

Electrocatalysts for highly efficient oxygen reduction reaction (ORR) are crucial for energy conversion and storage devices. Single‐atom catalysts with maximized metal utilization and altered electronic structure are the most promising alternatives to replace current benchmark precious metals. However, the atomic level understanding of the functional role for each species at the anchoring sites is still unclear and poorly elucidated. Herein, we report Fe single atom catalysts with the sulfur and oxygen functional groups near the atomically dispersed metal centers (Fe1/NSOC) for highly efficient ORR. The Fe1/NSOC delivers a half‐wave potential of 0.92 V vs. RHE, which is much better than those of commercial Pt/C (0.88 V), Fe single atoms on N‐doped carbon (Fe1/NC, 0.89 V) and most reported nonprecious metal catalysts. The spectroscopic measurements reveal that the presence of sulfur group induces the formation of epoxy groups near the FeN4S2 centers, which not only modulate the electronic structure of Fe single atoms but also participate the catalytic process to improve the kinetics. The density functional theory calculations demonstrate the existence of sulfur and epoxy group engineer the charges of Fe reactive center and facilitate the reductive release of OH* (rate‐limiting step), thus boosting the overall oxygen reduction efficiency.