Nickel–Platinum Alloy Nanocrystallites with High‐Index Facets as Highly Effective Core Catalyst for Lithium–Sulfur Batteries

Abstract

Elemental sulfur possesses an ultra-high theoretical specific capacity, while the practical application of sulfur in lithium-sulfur (Li-S) batteries is seriously hindered by the sluggish redox kinetics and serious shuttle effect. Enhancing the catalytic activity of the sulfur host by a rational structural design is the key to address these issues. Herein, for the first time, concave-nanocubic (CNC) nickel-platinum (Ni-Pt) alloys bounded by high-index facets (HIFs) are introduced as the core catalyst of sulfur for Li-S batteries. It is demonstrated that the CNC Ni-Pt alloy crystallites dispersed uniformly on graphene exhibit a high electrochemical activity to drive the conversion from intermediate lithium poly sulfides to solid discharged products. Benefiting from the accelerated redox kinetics by HIFs, the cathode delivers a low capacity damping of 0.025% per cycle for 1000 cycles at 1 C rate. In particular, a high reversible capacity of 664.9 mAh g −1 -cathode with cathode as active material can be achieved with high sulfur loading (8.8 mg cm −2 ) and low electrolyte usage (5 µL mg s −1). This study focuses on improving the catalytic activity of sulfur hosts by modulating the exposed facets of core catalyst and provides a new path for the structure optimizing of host materials in Li-S batteries.

Surface-Regulated Platinum–Copper Nanoframes in Electrochemical Reforming of Ethanol for Efficient Hydrogen Production

“…Introducing foreign elements to form Pt-based alloy materials could enhance electron conductivity, optimize the electron structure, and provide sufficient synergistic function of the material. In addition, a three-dimensional (3D) open structure with multi-channels could not only expose enough active sites and improve utilization of Pt but also limit the reactants in nanoscale spaces to increase the collision frequency during the catalytic reaction process. − The high-index facets are considered to be an open structure represented by a set of Miller indices { hkl }, which have rich low coordination atoms, providing more active sites for the catalytic process. − However, the reported performance of bifunctional catalysts for HER and EOR is still unsatisfactory. Therefore, it is challenging and significant to develop Pt-based alloy electrocatalysts with 3D open structures and high-index facets for superior bifunctional performance (HER and EOR).…”

FeCoNi Ternary Nano-Alloys Embedded in a Nitrogen-Doped Porous Carbon Matrix with Enhanced Electrocatalysis for Stable Lithium–Sulfur Batteries

“…A cathode substrate configured with boron-carbide (B 4 C) nanowires in situ grown on carbon nanofibers was synthesized and reported by Luo et al, which effectively enhanced the cycling stability of the LSBs . In addition to the introduction of a single metal compound, the use of alloy materials with upgraded catalytic activity through the synergism of different components proves another valid means as well. − Apart from the low cost of iron (Fe) and nickel (Ni), the performance of LSBs can be remarkably enhanced using iron and nickel alloys. As one kind of heterostructure, the metal alloy has many unique merits, including the advantages inherited from each component .…”

Kinetic Acceleration of Lithium Polysulfide Conversion via a Copper–Iridium Alloying Catalytic Strategy in Li–S Batteries

“…has been rarely explored in the LSBs. According to reports, the filling of the noble metal d-band originated from the difference in electronegativity between noble metals and transition metals, accompanied by a downshift in the central energy of the d-band, resulting in an optimized electronic structure and corresponding catalytic activity significantly higher than that of single metal-based catalysts. − Wang et al reported that the well-designed nickel–platinum alloy as a catalyst dispersedly loaded on graphene provides modest chemical anchoring for LiPSs, decreases the energy barriers of catalytic conversion, and expedites the kinetics of LiPS intermediates . Through investigation, we found that iridium (Ir) is a 5d transition metal with unique properties in electrochemical catalysis compared to some other noble metals (such as Au and Pt) because of its good compatibility with electrolytes, which is beneficial for reducing charge polarization. , Thus, it is a promising approach to tune the electronic structure of Ir sites by coupling the thiophilic Cu, which was highly conductive, naturally abundant, and of low-cost. , …”

“…16−18 Wang et al reported that the well-designed nickel−platinum alloy as a catalyst dispersedly loaded on graphene provides modest chemical anchoring for LiPSs, decreases the energy barriers of catalytic conversion, and expedites the kinetics of LiPS intermediates. 19 Through investigation, we found that iridium (Ir) is a 5d transition metal with unique properties in electrochemical catalysis compared to some other noble metals (such as Au and Pt) because of its good compatibility with electrolytes, which is beneficial for reducing charge polarization. 7,20 Thus, it is a promising approach to tune the electronic structure of Ir sites by coupling the thiophilic Cu, which was highly conductive, naturally abundant, and of low-cost.…”