Precisely tuning the coordination
environment of the metal center
and further maximizing the activity of transition metal–nitrogen
carbon (M-NC) catalysts for high-performance lithium–sulfur
batteries are greatly desired. Herein, we construct an Fe-NC material
with uniform and stable Fe-N2 coordination structure. The
theoretical and experimental results indicate that the unsaturated
Fe-N2 center can act as a multifunctional site for anchoring
lithium polysulfides (LiPSs), accelerating the redox conversion of
LiPSs and reducing the reaction energy barrier of Li2S
decomposition. Consequently, the batteries based on a porous carbon
nitride supported Fe-N2 site (Fe-N2/CN) host
exhibit excellent cycling performance with a capacity decay of 0.011%
per cycle at 2 C after 2000 cycles. This work deepens the understanding
of the relationship between electronic structure of M-NC sites and
the catalysis effect for the conversion of LiPSs. This strategy also
provides a potent guidance for the further application of M-NC materials
in advanced lithium–sulfur batteries.
A universal strategy is developed to construct a cascade Z‐Scheme system, in which an effective energy platform is the core to direct charge transfer and separation, blocking the unexpected type‐II charge transfer pathway. The dimension‐matched (001)TiO2‐g‐C3N4/BiVO4 nanosheet heterojunction (T‐CN/BVNS) is the first such model. The optimized cascade Z‐Scheme exhibits ≈19‐fold photoactivity improvement for CO2 reduction to CO in the absence of cocatalysts and costly sacrificial agents under visible‐light irradiation, compared with BVNS, which is also superior to other reported Z‐Scheme systems even with noble metals as mediators. The experimental results and DFT calculations based on van der Waals structural models on the ultrafast timescale reveal that the introduced T as the platform prolongs the lifetimes of spatially separated electrons and holes and does not compromise their reduction and oxidation potentials.
Die rationale Entwicklung effizienter Photokatalysatoren mit günstiger Ladungstrennung und breiter spektraler Absorption ist entscheidend für eine ökonomische Umwandlung von Solarenergie in chemische Energie. F. Q. Bai, J. Tang, L. Q. Jing et al. zeigen in ihrer Zuschrift auf S. 10989 H‐verbrückte ZnPc/BiVO4‐Nanokomposite als ultradünnen, räumlich angepassten 2D/2D‐Heteroübergang zur effizienten photokatalytischen CO2‐Reduktion über eine breite Region des sichtbaren Lichts.
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