Direct transformation of bulk copper into copper single sites via emitting and trapping of atoms

Developing highly efficient electrocatalysts with low cost is critical for the wide‐spread application of sustainable and renewable energy conversion technologies. Single‐atom catalysts (SACs) have attracted considerable attention owing to their high catalytic activity, selectivity, and stability. However, the high surface energy of the single atoms often results in an extremely low loading of metal atom catalysts with limited mass activity. In this context, densely populated SACs are more promising for practical applications due to their high active surface area and mass activity. Herein, the recent research progress of high loading (≥5 wt%) SACs for different electrocatalytic applications is summarized. An overview of various synthesis and characterization strategies of SACs is presented in this review. The influence of appropriate substrates on the preparation of high metal loading SACs is also discussed. In addition, this review provides valuable insights into the current challenges and future opportunities in the field of single‐atom catalysts.

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Section: Fabrication Of Densely Populated Sacsmentioning

confidence: 99%

Densely Populated Single Atom Catalysts

et al. 2019

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“…Despite less electronic conductivity and smaller BET specific surface area of mesoporous C 3 N 7 in comparison to mesoporous C 3 N 6 , the mesoporous C 3 N 7 exhibits higher catalytic activity than that of the mesoporous C 3 N 6 , which suggests that tailored atomic structure is mainly responsible for the superior catalytic activity of the mesoporous C 3 N 7 . The ORR performance of the mesoporous C 3 N 7 is better than those of pure carbon nitrides in the literature (see Table S3, Supporting Information), stressing the importance of engineering the chemical composition and core structure of carbon nitride for improvement of the ORR activity . Nevertheless, the ORR activity of the mesoporous C 3 N 7 still needs to be improved considering superior ORR activities of N‐doped carbons and Pt/C .…”

mentioning

confidence: 97%

Thermodynamically Stable Mesoporous C₃N₇ and C₃N₆ with Ordered Structure and Their Excellent Performance for Oxygen Reduction Reaction

Kim

Selvarajan

et al. 2019

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Carbon nitrides with a high N/C atomic ratio (>2) are expected to offer superior basicity and unique electronic properties. However, the synthesis of these nanostructures is highly challenging since many parts of the CN frameworks in the carbon nitride should be replaced with thermodynamically less stable NN frameworks as the nitrogen content increases. Thermodynamically stable C3N7 and C3N6 with an ordered mesoporous structure are synthesized at 250 and 300 °C respectively via a pyrolysis process of 5‐amino‐1H‐tetrazole (5‐ATTZ). Polymerization of the precursor to the ordered mesoporous C3N7 and C3N6 is clearly proved by X‐ray and electron diffraction analyses. A combined analysis including diverse spectroscopy and FDMNES and density functional theory (DFT) calculations demonstrates that the NN bonds are stabilized in the form of tetrazine and/or triazole moieties in the C3N7 and C3N6. The ordered mesoporous C3N7 represents the better oxygen reduction reaction (ORR) performances (onset potential: 0.81 V vs reversible hydrogen electrode (RHE), electron transfer number: 3.9 at 0.5 V vs RHE) than graphitic carbon nitride (g‐C3N4) and the ordered mesoporous C3N6. The study on the mechanism of ORR suggests that nitrogen atoms in the tetrazine moiety of the ordered mesoporous C3N7 act as active sites for its improved ORR activity.

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“…This implies a much rapid first electron transfer step at low over-potentials, [27] further demonstrating the excellent catalytic activity of NCN@CF 2 -950. The corresponding Koutecky-Levich (K-L) plots at different potentials (inset in Figure 5a) all show a linear trend, demonstrating the first-order reaction kinetics of NCN@CF 2 -950 electrode in the potential range of 0.3~0.7 V. [28] According to K-L equation, the electron transfer number (n) during the ORR process was calculated to be 3.95 at 0.7 V, close to the highly desired four-electron ORR pathway. The corresponding Koutecky-Levich (K-L) plots at different potentials (inset in Figure 5a) all show a linear trend, demonstrating the first-order reaction kinetics of NCN@CF 2 -950 electrode in the potential range of 0.3~0.7 V. [28] According to K-L equation, the electron transfer number (n) during the ORR process was calculated to be 3.95 at 0.7 V, close to the highly desired four-electron ORR pathway.…”

Section: Resultsmentioning

confidence: 83%

Metal‐Free Hybrid of Nitrogen‐Doped Nanocarbon@Carbon Networks for Highly Efficient Oxygen Reduction Electrocatalyst

Shi

Qin

et al. 2019

ChemElectroChem

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Further improving the oxygen reduction reaction (ORR) catalytic activity of carbon catalysts is highly challenging and remains a key issue to push forward their commercial progress as Pt alternatives in fuel cells and metal-air batteries. Herein, a facile and economic strategy was proposed to maximize the active sites exposed in porous carbon catalysts by growing dense Ndoped carbon nanonodules firmly located within carbon fiber networks (NCN@CF) via the in situ polymerization of dopamine on bacterial cellulose fibers and a subsequent carbonization process. This metal-free hybrid catalyst exhibits enhanced ORR activity and better stabilities against long duration and the methanol crossover effect than the commercial Pt/C catalyst in 0.1 M KOH. Notably, when the NCN@CF hybrid was used as an air electrode catalyst in a Zn-air battery, the as-fabricated battery presented a larger peak power density of 168 mW cm À 2 , higher specific capacity of 720.5 mA h g À 1 and energy density of 900.0 Wh kg À 1 compared to those based on commercial Pt/C and most N-doped carbon catalysts ever reported, evidencing its highly promising use as a Pt-alternative catalyst for the ORR.

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Direct transformation of bulk copper into copper single sites via emitting and trapping of atoms

Cited by 833 publications

References 35 publications

Densely Populated Single Atom Catalysts

Densely Populated Single Atom Catalysts

Thermodynamically Stable Mesoporous C₃N₇ and C₃N₆ with Ordered Structure and Their Excellent Performance for Oxygen Reduction Reaction

Metal‐Free Hybrid of Nitrogen‐Doped Nanocarbon@Carbon Networks for Highly Efficient Oxygen Reduction Electrocatalyst

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Direct transformation of bulk copper into copper single sites via emitting and trapping of atoms

Cited by 833 publications

References 35 publications

Densely Populated Single Atom Catalysts

Densely Populated Single Atom Catalysts

Thermodynamically Stable Mesoporous C3N7 and C3N6 with Ordered Structure and Their Excellent Performance for Oxygen Reduction Reaction

Metal‐Free Hybrid of Nitrogen‐Doped Nanocarbon@Carbon Networks for Highly Efficient Oxygen Reduction Electrocatalyst

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Thermodynamically Stable Mesoporous C₃N₇ and C₃N₆ with Ordered Structure and Their Excellent Performance for Oxygen Reduction Reaction