Trade-off effect of 3d transition metal doped boron nitride on anchoring polysulfides towards application in lithium-sulfur battery

Defect Spinel Aluminum Molybdenum Sulfide: A Dual-Function Catalyst for Polysulfide Conversion and Aluminum Intercalation in Aluminum-Sulfur Batteries

Aluminum-sulfur batteries (ASBs) are regarded as promising energy storage devices due to their cost-effectiveness and safety. However, ASBs suffer from problems of polysulfide shuttling and short lifetimes, which restrict their practical applications. In this work, defect spinel Aluminum molybdenum sulfide (AlMo4S8) embedded in carbon nanotubes synthesized via solid-state reaction is applied to ASBs. The carbon nanotube-connected spinel AlMo4S8 material effectively mitigates polysulfide shuttling while also contributing its own capacity in ASBs. Besides, AlMo4S8 serves as a "bi-directional catalyst" with bimetallic active sites to increase the ion transport pathway, effectively facilitating the reduction of polysulfides and the oxidation of Al2S3. The ASBs with AlMo4S8/CNTs@S cathode exhibit excellent electrochemical performance with high specific capacity (304.3 mAh g-1 at 500 mA g-1). The soft pack batteries fabricated with AlMo4S8/CNTs@S cathode (sulfur loading of 3.0 mg cm-2) maintain a stable capacity for more than 50 cycles.

Modulating the D-Band Center of Electrocatalysts for Enhanced Water Splitting

To tackle the global energy scarcity and environmental degradation, developing efficient electrocatalysts is essential for achieving sustainable hydrogen production via water splitting. Modulating the d-band center of transition metal electrocatalysts is an effective approach to regulate the adsorption energy of intermediates, alter reaction pathways, lower the energy barrier of the rate-determining step, and ultimately improve electrocatalytic water splitting performance. In this review, a comprehensive overview of the recent advancements in modulating the d-band center for enhanced electrocatalytic water splitting is offered. Initially, the basics of the d-band theory are discussed. Subsequently, recent modulation strategies that aim to boost electrocatalytic activity, with particular emphasis on the d-band center as a key indicator in water splitting are summarized. Lastly, the importance of regulating electrocatalytic activity through d-band center, along with the challenges and prospects for improving electrocatalytic water splitting performance by fine-tuning the transition metal d-band center, are provided.

Computational study on two-dimensional transition metal borides for enhanced lithium-sulfur battery performance: Insights on anchoring, catalytic activity, and solvation effects

The controlled modulation of surface functional groups, in conjunction with the intrinsic structural characteristics of MXene materials, shows great potential in alleviating the shuttle effect and improving the sluggish reaction kinetics in lithium-sulfur batteries (LSBs). This study delves into the impact of surface functional groups (T = O, S, F, and Cl) on V2B2 MBene concerning sulfur immobilization and kinetic catalytic properties through meticulous first-principles calculations. The results reveal that the establishment of T-Li bonds within V2B2T2 (T = O, S, F, and Cl) enhances the adsorption of lithium polysulfides (LiPSs). Moreover, the robust interactions between the T_p and V_d orbitals play a pivotal role in strengthening the T-V bond and reducing the energy barrier for Li2S decomposition. Comparative analyses underscore the outstanding performance of V2B2O2, showcasing a moderate adsorption strength for LiPSs, remarkable electrocatalytic activity for Li2S decomposition (with an energy barrier of 0.42 eV), and a low Li2S diffusion barrier (0.16 eV). These attributes facilitate effective anchoring and expedite reaction kinetics for LiPSs. Furthermore, the influences of solvation and temperature were found to have substantial impacts on the anchoring capability of V2B2T2 except for V2B2O2. This study establishes a critical theoretical framework and serves as a valuable reference for advancing MBene materials as cathodes for LSBs.

Modulation of d-Orbital Interactions in Dual-Atom Catalysts for Enhanced Polysulfide Anchoring and Kinetics in Lithium-Sulfur Batteries

Modulating the electronic structure is essential for improving the anchoring and catalytic capabilities of catalysts in lithium-sulfur batteries (LSBs). This study delves into the modulation of d-orbitals in transition metal dual-atom catalysts (DACs) supported by boron nitride and graphene (BNC) hybrid sheets for LSBs. This study reveals that the d-band center of the DACs, a key determinant of material chemical properties, is primarily determined by the electronic configuration of the dyz and dx2-y2 orbitals. Furthermore, the interaction between dz2 of transition metals and S_3 p orbitals is critical for the binding strength of LiPSs. By understanding these interactions, the functionality of DACs can be customized for optimal performance in LSBs. For example, the MnCrBNC catalyst with 10 d-electrons exhibits the optimal d-band center and demonstrates exceptional LiPSs binding capability, the lowest Li2S decomposition energy barrier, and the lowest Gibbs free energy of reaction for the rate-determining step of sulfur reduction. This study elucidates the fundamental mechanisms for designing high-performance LSB catalysts through electronic structure modulation.

Regulating the catalytic behaviour of iron oxyhydroxide by introducing Ni sites for facilitating polysulfide anchoring and conversion

The sluggish conversion kinetics and notorious shuttle effect of polysulfides are critical hindrances to practical implementation of lithium-sulfur batteries. Herein, bimetallic oxyhydroxide (FeNiOOH) as a functional sulfur host is proposed to overcome these obstacles. The introduction of Ni sites can modulate the electronic structure of the active sites to implement strong soluble polysulfide species immobilization and accelerate the conversion reaction kinetics of polysulfides, resulting in improved sulfur utilization and reduced polarization during the electrochemical reaction process. Benefiting from these advantages, FeNiOOH enables the sulfur cathode to deliver superior rate capability and cycling stability.

Descriptor-Driven Computational Design of Bifunctional Double-Atom Hydrogen Evolution and Oxidation Reaction Electrocatalysts for Rechargeable Hydrogen Gas Batteries

Rechargeable hydrogen gas batteries (RHGBs) have been attracting much attention as promising all-climate large-scale energy storage devices, which calls for low-cost and high-activity hydrogen evolution/oxidation reaction (HER/HOR) bifunctional electrocatalysts to replace the costly platinum-based catalysts. Based on density functional theory (DFT) computations, herein we report an effective descriptor-driven design principle to govern the HER/HOR electrocatalytic activity of double-atom catalysts (DACs) for RHGBs. We systematically investigate the d-band center variation of DACs and their correlations with HER/HOR free energies. We construct activity maps with the d-band center of DACs as a descriptor, which demonstrate that high HER/HOR electrocatalytic activity can be achieved with an appropriate d-band center of DACs. This work not only broadens the applicability of d-band center theory to the prediction of bifunctional HER/HOR electrocatalysts but also paves the way to fast screening and design of efficient and low-cost DACs to promote practical applications of RHGBs.