Catalytic water splitting driven by renewable electricity offers a promising strategy to produce molecular hydrogen, but its efficiency is severely restricted by the sluggish kinetics of the anodic ...water oxidation reaction. Amorphous catalysts are reported to show better activities of water oxidation than their crystalline counterparts, but little is known about the underlying origin, which retards the development of high performance amorphous oxygen evolution reaction (OER) catalysts. Herein based on cyclic voltammetry, electrochemical impedance spectroscopy, isotope labeling and in situ X-ray absorption spectroscopy (XAS) studies, we demonstrate that amorphous catalyst can be electrochemically activated to expose active sites in the bulk, thanks to the short range order of the amorphous structure, which greatly increases the number of active sites and thus improves the electrocatalytic activity of amorphous catalyst in water oxidation.
Abstract
Designing effective electrocatalysts for the carbon dioxide reduction reaction (CO
2
RR) is an appealing approach to tackling the challenges posed by rising CO
2
levels and realizing a ...closed carbon cycle. However, fundamental understanding of the complicated CO
2
RR mechanism in CO
2
electrocatalysis is still lacking because model systems are limited. We have designed a model nickel single‐atom catalyst (Ni SAC) with a uniform structure and well‐defined Ni‐N
4
moiety on a conductive carbon support with which to explore the electrochemical CO
2
RR. Operando X‐ray absorption near‐edge structure spectroscopy, Raman spectroscopy, and near‐ambient X‐ray photoelectron spectroscopy, revealed that Ni
+
in the Ni SAC was highly active for CO
2
activation, and functioned as an authentic catalytically active site for the CO
2
RR. Furthermore, through combination with a kinetics study, the rate‐determining step of the CO
2
RR was determined to be *CO
2
−
+H
+
→*COOH. This study tackles the four challenges faced by the CO
2
RR; namely, activity, selectivity, stability, and dynamics.
Cross‐relaxation among sensitizers is commonly regarded as deleterious in fluorescent materials, although favorable in photothermal agents. Herein, we coated Prussian blue (PB) on NaNdF4 ...nanoparticles to fabricate core–shell nanocomplexes with new cross relaxation pathways between the ladder‐like energy levels of Nd3+ ions and continuous energy band of PB. The photothermal conversion efficiency was improved exceptionally and the mechanism of the enhanced photothermal effect was investigated. In vivo photoacoustic imaging and photothermal therapy demonstrated the potential of the enhanced photothermal agents. Moreover, the concept of generating new cross‐relaxation pathways between different materials is proposed to contribute to the design of all kinds of enhanced photothermal agents.
Blau blüht der Nanopartikel: Durch die Beschichtung von NaNdF4‐Nanopartikeln mit Berliner Blau wurden Kern/Schale‐Nanokomplexe mit neuen Kreuzrelaxationspfaden zwischen den diskreten Energieniveaus der Nd3+‐Ionen und dem kontinuierlichen Energieband des Berliner Blau hergestellt. Hierdurch erhöht sich die photothermale Konversionseffizienz drastisch. Photoakustische Bildgebung und photothermale Therapie belegen in vivo das Potential der Nanokomplexe.
Designing effective electrocatalysts for the carbon dioxide reduction reaction (CO2RR) is an appealing approach to tackling the challenges posed by rising CO2 levels and realizing a closed carbon ...cycle. However, fundamental understanding of the complicated CO2RR mechanism in CO2 electrocatalysis is still lacking because model systems are limited. We have designed a model nickel single‐atom catalyst (Ni SAC) with a uniform structure and well‐defined Ni‐N4 moiety on a conductive carbon support with which to explore the electrochemical CO2RR. Operando X‐ray absorption near‐edge structure spectroscopy, Raman spectroscopy, and near‐ambient X‐ray photoelectron spectroscopy, revealed that Ni+ in the Ni SAC was highly active for CO2 activation, and functioned as an authentic catalytically active site for the CO2RR. Furthermore, through combination with a kinetics study, the rate‐determining step of the CO2RR was determined to be *CO2−+H+→*COOH. This study tackles the four challenges faced by the CO2RR; namely, activity, selectivity, stability, and dynamics.
Erfolgreicher Einzelgänger: Die In‐situ‐Reduktion von Nickel(II)‐2,9,16,23‐tetra(amino)phthalocyanin, verankert auf der Oberfläche von Kohlenstoffnanoröhren, ergibt einzelne Nickelatome. Spektroskopische Messungen dieses Einzelatomkatalysators zeigen, dass Ni+ ein hoch aktives katalytisches Zentrum für die Aktivierung und Reduktion von CO2 darstellt.
Ein Nickel‐Einzelatom‐Modellkatalysator mit gleichförmigen und wohldefinierten Ni‐N4‐Einheiten wurde durch Verknüpfung von molekularem Nickelphthalocyanin mit Kohlenstoffnanoröhren über kovalente ...C‐C‐Bindungen erhalten. Y. Huang, B. Liu et al. beschreiben in ihrem Forschungsartikel auf S. 808 einen hochaktiven Katalysator für die elektrochemische Reduktion von CO2 zu CO mit hohem Faradayschem Wirkungsgrad und hoher Turnover‐Frequenz. Das aktive Zentrum besteht aus einer in situ erzeugten Ni+‐Spezies.
Abstract
Development of efficient and affordable electrocatalysts in neutral solutions is paramount importance for the renewable energy. Herein, we report that the oxygen evolution reaction (OER) ...performance of Co
3
S
4
under neutral conditions can be enhanced by exposed octahedral planes and self‐adapted spin states in atomically thin nanosheets. A HAADF image clearly confirmed that the active octahedra with Jahn–Teller distortions were exposed exclusively. Most importantly, in the atomically thin nanosheets, the spin states of Co
3+
in the octahedral self‐adapt from low‐spin to high‐spin states. As a result, the synergistic effect endow the Co
3
S
4
nanosheets with superior OER performance, with exceptional low onset overpotentials of circa 0.31 V in neutral solutions, which is state‐of‐the‐art among inorganic non‐noble metal compounds.
Development of efficient and affordable electrocatalysts in neutral solutions is paramount importance for the renewable energy. Herein, we report that the oxygen evolution reaction (OER) performance ...of Co3S4 under neutral conditions can be enhanced by exposed octahedral planes and self‐adapted spin states in atomically thin nanosheets. A HAADF image clearly confirmed that the active octahedra with Jahn–Teller distortions were exposed exclusively. Most importantly, in the atomically thin nanosheets, the spin states of Co3+ in the octahedral self‐adapt from low‐spin to high‐spin states. As a result, the synergistic effect endow the Co3S4 nanosheets with superior OER performance, with exceptional low onset overpotentials of circa 0.31 V in neutral solutions, which is state‐of‐the‐art among inorganic non‐noble metal compounds.
Eine bessere Leistung in der Sauerstoffentwicklung an Co3S4 unter neutralen Bedingungen ergibt sich aus exponierten Oktaederflächen und selbstanpassenden Spinzuständen in dünnen Nanoschichten. Die Sauerstoffentwicklung an solchen Co3S4‐Nanoschichten setzt in neutraler Lösung bereits bei Überpotentialen von ca. 0.31 V ein.
Development of efficient and affordable electrocatalysts in neutral solutions is paramount importance for the renewable energy. Herein, we report that the oxygen evolution reaction (OER) performance ...of Co sub(3)S sub(4) under neutral conditions can be enhanced by exposed octahedral planes and self-adapted spin states in atomically thin nanosheets. A HAADF image clearly confirmed that the active octahedra with Jahn-Teller distortions were exposed exclusively. Most importantly, in the atomically thin nanosheets, the spin states of Co super(3+) in the octahedral self-adapt from low-spin to high-spin states. As a result, the synergistic effect endow the Co sub(3)S sub(4) nanosheets with superior OER performance, with exceptional low onset overpotentials of circa 0.31V in neutral solutions, which is state-of-the-art among inorganic non-noble metal compounds.Original Abstract: Eine bessere Leistung in der Sauerstoffentwicklung an Co sub(3)S sub(4) unter neutralen Bedingungen ergibt sich aus exponierten Oktaederflaechen und selbstanpassenden Spinzustaenden in duennen Nanoschichten. Die Sauerstoffentwicklung an solchen Co sub(3)S sub(4)-Nanoschichten setzt in neutraler Losung bereits bei Ueberpotentialen von ca. 0.31V ein.
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