Balanced Mass Transfer and Active Sites Density in Hierarchical Porous Catalytic Metal–Organic Framework for Enhancing Redox Reaction in Lithium–Sulfur Batteries

Abstract

Developing highly efficient catalysts, characterized by controllable pore architecture and effective utilization of active sites, is paramount in addressing the shuttle effect and sluggish redox kinetics of lithium polysulfides (LiPSs) in lithium–sulfur batteries (LSBs), which, however, remains a formidable challenge. In this study, a hierarchical porous catalytic metal–organic framework (HPC-MOF) with both appropriate porosity and abundant exposed catalytic sites is achieved through time-controlled precise pore engineering. It is revealed that the evolution of the porous structure and catalytic site density is time-dependent during the etching processes. The moderately etched HPC-MOF-M attains heterogeneous pores at various scales, where large apertures ensure fast mass transfer and micropores inherit high-density catalytic sites, enhancing utilization and catalytic kinetics at internal catalytic sites. Capitalizing on these advantages, LSB incorporating the HPC-MOF-M interlayer demonstrates a 164.6% improvement in discharge capability and an 83.3% lower decay rate over long-term cycling at 1.0C. Even under high sulfur loading of 7.1 mg cm–2 and lean electrolyte conditions, the LSB exhibits stable cycling for over 100 cycles. This work highlights the significance of balancing the relationship between mass transfer and catalytic sites through precise chemical regulation of the porous structure in catalytic MOFs, which are anticipated to inspire the development of advanced catalysts for LSBs.

Multi-Enzyme Cascade Nanoreactors for High-Throughput Immunoassay: Transitioning Concept in Lab to Application in Community

“…A class of MOFs with mesoporous cavities is a remarkable material, particularly for enzyme immobilization applications, as MOFs offer several inherent advantages over micropore MOFs: (i) the enzyme loading is extremely high due to the increase in pore volume and void space; (ii) the enzymes may physically adsorb into the cavities rather than overhanging the surface of the MOFs, which contributes to increased stability of recycling and reduced leaching; and (iii) the pore diameter of the backbone can offer size selectivity for specific substrates, which is difficult to achieve with surface-immobilized enzymes. − However, achieving the modulation from microporous MOFs to mesoporous MOFs remains challenging considering the strong interactions between the robust organic ligands and the presence of defective mesoporous voids.…”