An ultrahigh pyridinic N-content-doped porous carbon monolith is reported, and the content of pyridinic N reaches up to 10.1% in overall material (53.4 ± 0.9% out of 18.9 ± 0.4% N content), being higher than most of previously reported N-doping carbonaceous materials, which exhibit greatly improved electrochemical performance for potassium storage, especially in term of the high reversible capacity. Remarkably, the pyridinic N-doped porous carbon monolith (PNCM) electrode exhibits high initial charge capacity of 487 mAh g at a current density of 20 mA g , which is one of the highest reversible capacities among all carbonaceous anodes for K-ion batteries. Moreover, the K-ion full cell is successfully assembled, demonstrating a high practical energy density of 153.5 Wh kg . These results make PNCM promising for practical application in energy storage devices and encourage more investigations on a similar potassium storage system.
Highly uniform core/double-shell-structured β-NaYF4:Er(3+),Yb(3+)@SiO2@TiO2 hexagonal sub-microprisms are prepared and employed in dye-sensitized solar cells (DSCs) internally. This work paves a facile way to enable the most-efficient upconversion material (β-NaYF4:Er(3+),Yb(3+)) to be used as scattering and upconversion centers in the photoelectrode of a DSC.
Carbon‐based materials are considered to be one of the most promising materials for negative electrodes of the future, because of their good chemical stability, high electrical conductivity, and environmental benignity. However, to date, the underlying principles of K‐ion storage in carbonaceous anodes remain elusive, which greatly hinders the development of such a category of anodes. Herein, the ultrastable K‐ion storage of carbonaceous anode through systematic analyses, including comprehensive electrochemical characterizations, kinetics calculations, and structural/compositional evolution mechanism studies, is theoretically elucidated and experimentally verified. Specifically, it is found that the uniquely envelope‐like nitrogen‐doped carbon nanosheets with high pseudocapacitive could bring ultrastable storage of potassium ions, delivering a high initial reversible capacity of 367 mAh g−1 at a current density of 50 mA g−1 and retain 70.5 and 75.6% at current densities of 500 and 1000 mA g−1 after 1000th cycle, respectively. This study could enlighten researchers on further progress in the field of carbonaceous K‐ion battery negative electrode with a long cycle life.
Nitrogen-doped graphene-supported single atoms convert CO2 to CO, but fail to provide further hydrogenation to methane – a finding attributable to the weak adsorption of CO intermediates. To regulate the adsorption energy, here we investigate the metal-supported single atoms to enable CO2 hydrogenation. We find a copper-supported iron-single-atom catalyst producing a high-rate methane. Density functional theory calculations and in-situ Raman spectroscopy show that the iron atoms attract surrounding intermediates and carry out hydrogenation to generate methane. The catalyst is realized by assembling iron phthalocyanine on the copper surface, followed by in-situ formation of single iron atoms during electrocatalysis, identified using operando X-ray absorption spectroscopy. The copper-supported iron-single-atom catalyst exhibits a CO2-to-methane Faradaic efficiency of 64% and a partial current density of 128 mA cm−2, while the nitrogen-doped graphene-supported one produces only CO. The activity is 32 times higher than a pristine copper under the same conditions of electrolyte and bias.
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