Integrating sulfur cathodes with effective catalysts to accelerate polysulfide conversion is a suitable way for overcoming the serious shuttling and sluggish conversion of polysulfides in ...lithium–sulfur batteries. However, because of the sharp differences in the redox reaction kinetics and complicated phase transformation of sulfur, a single‐component catalyst cannot consistently accelerate the entire redox process. Herein, hierarchical and defect‐rich Co3O4/TiO2 p–n junctions (p‐Co3O4/n‐TiO2‐HPs) are fabricated to implement the sequential catalysis of S8(solid) → Li2S4(liquid) → Li2S(solid). Co3O4 sheets physiochemically immobilize the pristine sulfur and ensure the rapid reduction of S8 to Li2S4, while TiO2 dots realize the effective precipitation of Li2S, bridged by the directional migration of polysulfides from p‐type Co3O4 to n‐type TiO2 attributed to the interfacial built‐in electric field. As a result, the sulfur cathode coupled with p‐Co3O4/n‐TiO2‐HPs delivers long‐term cycling stability with a low capacity decay of 0.07% per cycle after 500 cycles at 10 C. This study demonstrates the synergistic effect of the built‐in electric field and heterostructures in spatially enhancing the stepwise conversion of polysulfides, which provides novel insights into the interfacial architecture for rationally regulating the polysulfide redox reactions.
Novel hierarchical and defect‐rich Co3O4/TiO2 p–n junctions with built‐in electric field are designed as the host materials of sulfur electrodes for Li–S batteries. The elaborate p–n junctions not only induce the directional migration of lithium polysulfides to suppress the dissolution of sulfur intermediates into the electrolyte but also implement the spatially sequential catalysis to ensure the superior utilization of sulfur.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The performance of aqueous Zn ion batteries (AZIBs) is highly dependent on inner Helmholtz plane (IHP) chemistry. Notorious parasitic reactions containing hydrogen evolution reactions (HER) and Zn ...dendrites both originate from abundant free H2O and random Zn deposition inside active IHP. Here, we report a universal high donor number (DN) additive pyridine (Py) with only 1 vol. % addition (Py‐to‐H2O volume ratio), for regulating molecule distribution inside IHP. Density functional theory (DFT) calculations and molecular dynamics (MD) simulation verify that incorporated Py additive could tailor Zn2+ solvation sheath and exclude H2O molecules from IHP effectively, which is in favor of preventing H2O decomposition. Consequently, even at extreme conditions such as high depth of discharge (DOD) of 80 %, the symmetric cell based on Py additive can sustain approximately 500 h long‐term stability. This efficient strategy with high DN additives furnishes a promising direction for designing novel electrolytes and promoting the practical application of AZIBs, despite inevitably introducing trace organic additives.
The performance of aqueous Zn‐ion batteries is improved by regulating the inner Helmholtz plane (IHP) chemistry. Pyridine (Py) as high donor number organic electrolyte additive (only 1 vol. % addition) is used to efficiently regulate the solvation sheath structure, which results in depressed H2O activity at the IHP interface. The thus‐formed IHP interface enables a superior stable Zn anode with high reversibility and utilization rate.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The lithium–sulfur (Li–S) battery is considered as an appealing candidate for next‐generation electrochemical energy storage systems because of high energy and low cost. Nonetheless, its development ...is plagued by the severe polysulfide shuttling and sluggish reaction kinetics. Although single‐atom catalysts (SACs) have emerged as a promising remedy to expedite sulfur redox chemistry, the mediocre single‐atom loading, inferior atomic utilization, and elusive catalytic pathway handicap their practical application. To tackle these concerns, in this work, unsaturated Fe single atoms with high loading capacity (≈6.32 wt%) are crafted on a 3D hierarchical C3N4 architecture (3DFeSA‐CN) by means of biotemplated synthesis. By electrokinetic analysis and theoretical calculations, it is uncovered that the 3DFeSA‐CN harnesses robust electrocatalytic activity to boost dual‐directional sulfur redox. As a result, S@3DFeSA‐CN can maintain a durable cyclic performance with a negligible capacity decay rate of 0.031% per cycle over 2000 cycles at 1.0 C. More encouragingly, an assembled Li–S battery with a sulfur loading of 5.75 mg cm−2 can harvest a high areal capacity of 6.18 mAh cm−2. This work offers a promising solution to optimize the carbonaceous support and coordination environment of SACs, thereby ultimately elevating dual‐directional sulfur redox in pragmatic Li–S batteries.
An Fe–N2 single‐atomic catalyst accommodated by a biomorphic hierarchical C3N4 support from a biomass template readily boosts the dual‐directional conversion kinetics of lithium sulfide and realizes high‐performance Li−S batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Utilizing reversible lattice oxygen redox (OR) in battery electrodes is an essential strategy to overcome the capacity limitation set by conventional transition metal redox. However, lattice OR ...reactions are often accompanied with irreversible oxygen oxidation, leading to local structural transformations and voltage/capacity fading. Herein, it is proposed that the reversibility of lattice OR can be remarkably improved through modulating transition metal–oxygen covalency for layered electrode of Na‐ion batteries. By developing a novel layered P2‐Na0.6Mg0.15Mn0.7Cu0.15O2 electrode, it is demonstrated that the highly electronegative Cu dopants can improve the lattice OR reversibility to 95% compared to 73% for Cu‐free counterpart, as directly quantified through high‐efficiency mapping of resonant inelastic X‐ray scattering. Crucially, the large energetic overlap between Cu 3d and O 2p states dictates the rigidity of oxygen framework, which effectively mitigates the structural distortion of local oxygen environment upon (de)sodiation and leads to the enhanced lattice OR reversibility. The electrode also exhibits a completely solid‐solution reaction with an ultralow volume change of only 0.45% and a reversible metal migration upon cycling, which together ensure the improved electrochemical performance. These results emphasize the critical role of transition metal–oxygen covalency for enhancing the reversibility of lattice OR toward high‐capacity electrodes employing OR chemistry.
Instead of activating the oxygen oxidation activity by construction of overwhelming nonbonding oxygen states, it is more crucial to enhance the reversibility of lattice oxygen redox reactions of layered battery electrodes through modulating transition metal (TM) O covalency, which concurrently suppresses the phase transition and irreversible TM migration, thus leading to the improved structural stability and electrochemical performance.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Fundamentally understanding the structure–property relationship is critical to design advanced electrocatalysts for lithium‐sulfur (Li−S) batteries, which remains a formidable challenge. Herein, by ...manipulating the regulable cations in spinel oxides, their geometrical‐site‐dependent catalytic activity for sulfur redox is investigated. Experimental and theoretical analyses validate that the modulation essence of cooperative catalysis of lithium polysulfides (LiPSs) is dominated by LiPSs adsorption competition between Co3+ tetrahedral (Td) and Mn3+ octahedral (Oh) sites on Mn3+Oh−O−Co3+Td backbones. Specifically, high‐spin Co3+Td with stronger Co−S covalency anchors LiPSs persistently, while electron delocalized Mn3+Oh with adsorptive orbital (dz2) functions better in catalyzing specialized LiPSs conversion. This work inaugurates a universal strategy for sculpting geometrical configuration to achieve charge, spin, and orbital topological regulation in electrocatalysts for Li−S batteries.
The charge, spin, and orbital topological regulation behind attractive physicochemical properties functions as a universal descriptor for determining the geometrical‐site‐dependent catalysis. By tuning cationic geometric configuration in spinel oxides, the lithium polysulfides (LiPSs) adsorption competition on Mn3+Oh−O−Co3+Td backbones is well leveraged to spark the cooperative catalysis of LiPSs in lithium‐sulfur batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The sustainable production of methane (CH4) via the electrochemical conversion of carbon dioxide (CO2) is an appealing approach to simultaneously mitigating carbon emissions and achieving energy ...storage in chemical bonds. Copper (Cu) is a unique material to produce hydrocarbons and oxygenates. However, selective methane generation on Cu remains a great challenge due to the preferential *CO dimerization pathway toward multi‐carbon (C2+) products at neighboring catalytic sites. Herein, a conjugated copper phthalocyanine polymer (CuPPc) is designed by a facile solid‐state method for highly selective CO2‐to‐CH4 conversion. The spatially isolated CuN4 sites in CuPPc favor the *CO protonation to generate the key *CHO intermediate, thus significantly promoting the formation of CH4. As a result, the CuPPc catalyst exhibits a high CH4 Faradaic efficiency of 55% and a partial current density of 18 mA cm−2 at −1.25 V versus the reversible hydrogen electrode. It also stably operates for 12 h. This study may offer a new solution to regulating the chemical environment of the active sites for the development of highly efficient copper‐based catalysts for electrochemical CO2 reduction.
A conjugated copper phthalocyanine polymer (CuPPc) is prepared by a solid‐state polymerization method. It features spatially separated copper sites coordinated with pyrrolic nitrogen, which are believed to effectively suppress *CO dimerization and promote *CO protonation. Great activity and selectivity for the electrochemical CH4 production are measured as a result.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Selenium cathodes have attracted much attention because of the high electronic conductivity and energy density. However, the shuttle effect of lithium polyselenides (LiPSes) leads to rapid capacity ...fading, hindering the practical application of lithium-selenium (Li-Se) batteries. Herein, an ultrafine MoC catalyst has been synthesized and utilized to accelerate the conversion from liquid LiPSes to solid Li
2
Se
2
/Li
2
Se, leading to suppressed shuttle effect and thus improved battery performance. Our present study provides valuable inspiration to the future exploration for the rational design of high-efficient catalysts for practical Li-Se batteries.
An ultrafine MoC catalyst was synthesized and utilized to accelerate the conversion from liquid LiPSes to solid Li
2
Se
2
/Li
2
Se, leading to suppressed shuttle effect and thus improved electrochemical performance of Li-Se batteries.
There has been increasing interests in π–d conjugated coordination polymers (CCPs) for energy storage because of their rapid charge transfer through long‐range planar π–d conjugation between ligands ...and metal centers. Nevertheless, currently reported CCPs for energy storage are mostly based on 1D or 2D structures. There are few 3D CCPs reported to date because of the great challenge in constructing nonplanar coordination geometries, let alone their applications in multivalent ions storage. Herein, a triphenylene‐catecholate‐based 3D CCP (Mn‐HHTP) is successfully synthesized assembled from the multidentate chelating groups of hexahydroxytriphenylene (HHTP) ligands and their isotropic coordination with Mn2+ ions. The 3D conjugated structure of Mn‐HHTP enables an exceptional cycle life of >4000 cycles at 0.5 A g−1 for multivalent Mg2+ ion storage, which is far superior to most organic and inorganic electrode materials. Experimental characterizations combined with theoretical calculations indicate that the semiquinone radicals at the HHTP ligands are the electroactive centers for Mg2+ ions storage. The excellent performance of Mn‐HHTP opens a new avenue towards the design of 3D CCPs for long‐life rechargeable magnesium‐ion batteries.
A new 3D π‐d conjugated polymer (Mn‐HHTP) is prepared assembled from the multidentate chelating groups of HHTP ligands and their isotropic coordination with Mn2+ ions. The unique 3D conjugated structure promotes the electron transfer and Mg2+ ion diffusion throughout the framework, and as a result, enables a ultralong cycle life of 4500 cycles as the cathode material of magnesium‐ion batteries.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Photocatalytic CO2 reduction to value-added chemicals is appealing but challenging, especially under dilute CO2 conditions. Herein, we present a molecular modulation strategy for porous ...metal–salophen organic frameworks (M-SOFs), involving cooperative regulation of the catalytically active metal centers and their local coordination environments for selective photocatalytic CO2 reduction across a wide range of CO2 concentrations. The optimal Ni-SOF shows a remarkable photocatalytic CO production rate of 16 908 μmol h−1 g−1 and near-unity selectivity under a pure CO2 atmosphere, along with excellent structural stability. More impressively, it largely preserves the catalytic activity and selectivity even when exposed to dilute CO2 (5–20 vol%). Both experimental and theoretical analyses support that the specific Ni–N2O2 coordination environment in the Ni-SOF endows it with strong CO2 binding capacity. This, coupled with nanoporous skeletons, enhances local CO2 enrichment and facilitates its subsequent conversion at the catalytic centers, thereby leading to superior photocatalytic performances at various CO2 concentrations.
Rational design of sulfur host materials to synergize the retention and catalysis of lithium polysulfides (LiPSs) is of great significance to accomplish efficient sulfur electrochemistry for ...lithium-sulfur (Li-S) batteries. Herein, we have elaborately designed Fe single atom decorated porous carbon nanofibers (FeSA-PCNF) through electrospinning to construct self-standing and binder-free cathodes for Li-S batteries. The unique architecture of FeSA-PCNF with interconnected fibrous networks and hierarchical porous structures guarantees rapid charge transfer kinetics as well as abundant active interfaces for LiPS conversions. Moreover, the highly active FeN
4
moieties with surrounding graphitic N dopants embedded in the porous carbon nanofibers ensure strong chemisorption and superior electrocatalytic conversion towards LiPSs. As a consequence, the Li-S batteries assembled with FeSA-PCNF demonstrate superior electrochemical performances with a high rate capability of 791 mA h g
−1
at 5C and a low capacity decay rate of 0.048% per cycle after 500 cycles at 2C. More encouragingly, a high areal capacity of 11.1 mA h cm
−2
is achieved after 50 cycles with an ultrahigh sulfur loading of 17 mg cm
−2
and a low electrolyte/sulfur ratio of 5 μl mg
−1
. This work presents a promising strategy for rational design of self-standing and binder-free cathodes for practically feasible and high-performance Li-S batteries.
Self-standing sulfur cathodes with fibrous skeletons and porous structures were fabricated by incorporating Fe single atoms into electrospun carbon nanofibers, leading to enhanced polysulfide retention and catalysis for Li-S batteries.
