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Highly active and durable electrocatalysts are of great significance to accelerate the sluggish oxygen evolution and oxygen reduction reaction (OER and ORR) which are indispensable processes in practical devices such as metal–air batteries. Herein, the authors integrate morphological design with compositional manipulation, and successfully achieve well-defined CoNiFe sulfide mesoporous nanospheres (CoNiFe-S MNs). The as-prepared CoNiFe-S MNs exhibit superior OER and ORR catalytic activity, delivering a low overpotential of only 199 mV at a current density of 10 mA cm−2 in 1 m KOH solution and a half-wave potential of 0.78 V in 0.1 m KOH solution toward OER and ORR, respectively. The CoNiFe-S MNs involved Zn–air battery exhibits remarkable charge–discharge performance (voltage gap of 0.76 V at 2 mA cm−2) and high power density (over 140 mW cm−3). Extended-time durability tests validate the structural recoverability of the mesoporous morphology, and the remarkable performance can be attributed to the intrinsic synergistic effect of heterometallic ions. It is believed that the method could pave the way for the design of novel electrocatalysts for Zn–air batteries.

Electrocatalytic CO2 reduction (CO2R) coupled with renewable electricity has been considered as a promising route for the sustainability transition of energy and chemical industries. However, the unsatisfactory yield of desired products, particularly multicarbon (C2+) products, has hindered the implementation of this technology. This work describes a strategy to enhance the yield of C2+ product formation in CO2R by utilizing spatial confinement effects. The finite element simulation results suggest that increasing the number of shells in the catalyst wil lead to a high local concentration of *CO and promotes the formation of C2+ products. Inspired by this, Cu nanoparticles are synthesized with desired hollow multi‐shell structures. The CO2 reduction results confirm that as the number of shells increase, the hollow multi‐shell copper catalysts exhibit improved selectivity toward C2+ products. Specifically, the Cu catalyst with 4.4‐shell achieved a high selectivity of over 80% toward C2+ at a current density of 900 mA cm−2. Evidence from in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy unveils that the multi‐shell Cu catalyst exhibits an enhanced *COatop coverage and the stronger interaction with *COatop compared to commercial Cu, confirming the simulation results. Overall, the work promises an effective approach for boosting CO2R selectivity toward value‐added chemicals. [ABSTRACT FROM AUTHOR]

As a bridge between nanocrystal catalysts and single‐atom catalysts, single‐unit‐cell catalysts seem at first glance to be unavailable for catalysis due to quantum effects and synthetic difficulties. Here, 24 nm Cu9S5 nanowires are synthesized via the LaMer pathway. Interestingly, when polyoxometalate (POM) clusters are introduced during the nucleation process, the 0.9 nm Cu9S5 nanowires are finally formed via covalent co‐assembly, analog to A–B–A–B‐type block co‐polymerization in the polymer field ("A" and "B" represent Cu9S5 unit cells and POM clusters, respectively). Multiple characterizations show that Cu9S5 exists as single‐unit‐cell structure. Therefore, each unit cell can work as an isolated active site. The single‐unit‐cell structure exhibits higher electrocatalytic activity and Faradaic efficiency (FE) of formic acid (82.0% at −0.8 V vs reversible hydrogen electrode (RHE)) during CO2 electroreduction, while the nanocrystal structure generates HCOO−, methanol, and ethanol with low FEs. This study suggests that the single‐unit‐cell catalyst displays great potential for precise catalysis by the finite size effect. [ABSTRACT FROM AUTHOR]