The electrochemical CO2 reduction reaction (CO2RR) is of great importance to tackle the rising CO2 concentration in the atmosphere. The CO2RR can be driven by renewable energy sources, producing precious chemicals and fuels, with the implementation of this process largely relying on the development of low‐cost and efficient electrocatalysts. Recently, a range of heterogeneous and potentially low‐cost single‐atom catalysts (SACs) containing non‐precious metals coordinated to earth‐abundant elements have emerged as promising candidates for the CO2RR. Unfortunately, the real catalytically active centers and the key factors that govern the catalytic performance of these SACs remain ambiguous. Here, this ambiguity is addressed by developing a fundamental understanding of the CO2RR‐to‐CO process on SACs, as CO accounts for the major product from CO2RR on SACs. The reaction mechanism, the rate‐determining steps, and the key factors that control the activity and selectivity are analyzed from both experimental and theoretical studies. Then, the synthesis, characterization, and the CO2RR performance of SACs are discussed. Finally, the challenges and future pathways are highlighted in the hope of guiding the design of the SACs to promote and understand the CO2RR on SACs.

Due to the abundant potassium resource on the Earth’s crust, researchers now have become interested in exploring high-performance potassium-ion batteries (KIBs). However, the large size of K+ would hinder the diffusion of K ions into electrode materials, thus leading to poor energy/power density and cycling performance during the depotassiation/potassiation process. So, few-layered V5S8 nanosheets wrapping a hollow carbon sphere fabricated via a facile hollow carbon template induced method could reversibly accommodate K storage and maintain the structure stability. Hence, the as-obtained V5S8@C electrode enables rapid and reversible storage of K+ with a high specific capacity of 645 mAh/g at 50 mA/g, a high rate capability, and long cycling stability, with 360 and 190 mAh/g achieved after 500 and 1000 cycles at 500 and 2000 mA/g, respectively. The excellent electrochemical performance is superior to the most existing electrode materials. The DFT calculations reveal that V5S8 nanosheets have high electrical conductivity and low energy barriers for K+ intercalation. Furthermore, the reaction mechanism of the V5S8@C electrode in KIBs is probed via the in operando synchrotron X-ray diffraction technique, and it indicates that the V5S8@C electrode undergoes a sequential intercalation (KV5S8) and conversion reactions (K2S3) reversibly during the potassiation process.

Electrochemical carbon dioxide (CO 2 )r eduction reaction (CO 2 RR) is an attractive approach to deal with the emission of CO 2 and to produce valuable fuels and chemicals in ac arbon-neutral way.M any efforts have been devoted to boost the activity and selectivity of high-value multicarbon products (C 2+ )o nC u-based electrocatalysts.H owever,C ubased CO 2 RR electrocatalysts suffer from poor catalytic stability mainly due to the structural degradation and loss of active species under CO 2 RR condition. To date,most reported Cu-based electrocatalysts present stabilities over dozenso f hours,w hich limits the advance of Cu-based electrocatalysts for CO 2 RR. Herein, ap orous chlorine-doped Cu electrocatalyst exhibits high C 2+ Faradaic efficiency (FE) of 53.8 %at À1.00 Vv ersus reversible hydrogen electrode (V RHE ). Importantly,the catalyst exhibited an outstanding catalytic stability in long-term electrocatalysis over 240 h. Experimental results show that the chlorine-induced stable cationic Cu 0 /Cu + species and the well-preserved structure with abundant active sites are critical to the high FE of C 2+ in the long-term run of electrochemical CO 2 reduction.

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Here, we report a universal single-atom coating (SAC) strategy by taking advantage of the rich chemistry of tannic acid (TA). TA units not only selfassemble into a cross-linked porous polyphenolic framework, but also can grip on different substates via multiple binding modes. Benefiting from the diverse chelating ability of TA, a series of mono-, and bimetallic SACs can be formed on substrates of different materials (e. g., carbon, SiO 2 , TiO 2 , MoS 2 ), dimensions (0D-3D) and sizes (50 nm-5 cm). By contrast, uniform SAC cannot be achieved using common approaches such as pyrolysis of metal-dopamine complexes or metal-organic frameworks. As a proof-of-concept demonstration, two Co SACs immobilized on graphene and TiO 2 were prepared. The former one shows six-fold higher mass activity than Pt/C toward oxygen reduction. The latter one displays outstanding photocatalytic activity owing to the high activity of the single atoms and the formation of the single-atom coating-TiO 2 heterojunction.