Construction of internal electric fields (IEFs) is crucial to realize efficient charge separation for charge-induced redox reactions, such as water splitting and CO2 reduction. However, a quantitative understanding of the charge transfer dynamics modulated by IEFs remains elusive. Here, electron microscopy study unveils that the non-equilibrium photo-excited electrons are collectively steered by two contiguous IEFs within binary (001)/(200) facet junctions of BiOBr platelets, and they exhibit characteristic Gaussian distribution profiles on reduction facets by using metal co-catalysts as probes. An analytical model justifies the Gaussian curve and allows us to measure the diffusion length and drift distance of electrons. The charge separation efficiency, as well as photocatalytic performances, are maximized when the platelet size is about twice the drift distance, either by tailoring particle dimensions or tuning IEF-dependent drift distances. The work offers great flexibility for precisely constructing high-performance particulate photocatalysts by understanding charge transfer dynamics.

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Lithium sulfur batteries have been regarded as promising energy storage devices due to their superiority in energy density. However, the low sulfur loading, low active material utilization, and poor cycling stability restrict their commercial applications. Herein, we prepared a three-dimensional structure of SnS 2 nanoplates decorated on nitrogen-doped carbon nanofibers (3D SnS 2 @N-CNFs) by an electrospinning process followed by a hydrothermal technique. The 3D freestanding SnS 2 @N-CNFs were applied as the current collector and polymeric binder containing a Li 2 S 6 catholyte for lithium polysulfide batteries. The obtained SnS 2 @N-CNFs show the strong physicochemical adsorption of polysulfides and can effectively reduce the electrochemical polarization. The cell with SnS 2 @N-CNFs exhibits high electrochemical performance. As a result, SnS 2 @N-CNFs with high sulfur loading of approximately 7.11 mg displayed the first discharge capacity of 1010 mAh g −1 at 0.2 C with 0.08% capacity decay per cycle over 150 cycles. Meanwhile, the electrode with sulfur loading up to 22.65 mg also exhibits an extremely high capacity of 14.67 mAh, much higher than commonly presented blade-cast sulfur electrodes. The fibrous membrane is promising for assembling with high sulfur loading, which exhibits a superior electrochemical performance in lithium sulfur batteries.

Summary Three‐dimensional (3D) nitrogen‐doped carbon nanofibers (N‐CNFs) which were originating from nitrogen‐containing zeolitic imidazolate framework‐8 (ZIF‐8) were obtained by a combined electrospinning/carbonization technique. The pores uniformly distributed in N‐CNFs result in the improvement of electrical conductivity, increasing of BET surface area (142.82 m2 g−1), and high porosity. The as‐synthesized 3D free‐standing N‐CNFs membrane was applied as the current collector and binder free containing Li2S6 catholyte for lithium‐sulfur batteries. As a novel composite cathode, the free‐standing N‐CNFs/Li2S6 membrane shows more stable electrochemical behavior than the CNFs/Li2S6 membrane, exhibiting a high first‐cycle discharge specific capacity of 1175 mAh g−1at 0.1 C and keeping discharge specific capacity of 702 mAh g−1 at higher rate. More importantly, as the sulfur mass in cathodes was increased at 7.11 mg, the N‐CNFs/Li2S6 membrane delivered 467 mAh g−1after 150 cycles at 0.2 C. The excellent electrochemical properties of N‐CNFs/Li2S6 membrane can be ascribed to synergistic effects of high porosity and nitrogen‐doping in N‐CNFs from carbonized ZIF‐8, illustrating collective effects of physisorption and chemisorption for lithium polysulfides in discharge‐charge processes.

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