With recent technological advances, the demand for renewable energy is ever growing. Polymer electrolyte membrane fuel cells (PEMFCs) have shown great promise in subduing various environmental and energy issues. However, the use of a platinum (Pt) electrocatalyst on both cathode and anode sides of the PEMFCs has caused economical and sustainability hurdles in the commercialization of such devices. To alleviate these problems with Pt catalysts, various avenues have been researched and used. In the present Review, we have tried to look into the problems associated with the stability of the Pt-based electrocatalysts. Here, the scope of the current Review is categorized into three issues regarding the stability of Pt electrocatalysts: shape-controlled structure, alloy and core–shell structure, and supporting materials for Pt-based electrocatalysts. Major factors influencing the stability of the Pt-based electrocatalysts have been discussed, and various parameters needed for increasing the stability are also considered.

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Despite their high theoretical energy density and low cost, lithium–sulfur batteries (LSBs) suffer from poor cycle life and low energy efficiency owing to the polysulfides shuttle and the electronic insulating nature of sulfur. Conductivity and polarity are two critical parameters for the search of optimal sulfur host materials. However, their role in immobilizing polysulfides and enhancing redox kinetics for long‐life LSBs are not fully understood. This work has conducted an evaluation on the role of polarity over conductivity by using a polar but nonconductive platelet ordered mesoporous silica (pOMS) and its replica platelet ordered mesoporous carbon (pOMC), which is conductive but nonpolar. It is found that the polar pOMS/S cathode with a sulfur mass fraction of 80 wt% demonstrates outstanding long‐term cycle stability for 2000 cycles even at a high current density of 2C. Furthermore, the pOMS/S cathode with a high sulfur loading of 6.5 mg cm−2 illustrates high areal and volumetric capacities with high capacity retention. Complementary physical and electrochemical probes clearly show that surface polarity and structure are more dominant factors for sulfur utilization efficiency and long‐life, while the conductivity can be compensated by the conductive agent involved as a required electrode material during electrode preparation. The present findings shed new light on the design principles of sulfur hosts towards long‐life and highly efficient LSBs.

Lithium-sulfur batteries have theoretical specific energy higher than state-of-the-art lithium-ion batteries. However, from a practical perspective, these batteries exhibit poor cycle life and low energy content owing to the polysulfides shuttling during cycling. To tackle these issues, researchers proposed the use of redox-inactive protective layers between the sulfur-containing cathode and lithium metal anode. However, these interlayers provide additional weight to the cell, thus, decreasing the practical specific energy. Here, we report the development and testing of redox-active interlayers consisting of sulfur-impregnated polar ordered mesoporous silica. Differently from redox-inactive interlayers, these redox-active interlayers enable the electrochemical reactivation of the soluble polysulfides, protect the lithium metal electrode from detrimental reactions via silica-polysulfide polar-polar interactions and increase the cell capacity. Indeed, when tested in a non-aqueous Li-S coin cell configuration, the use of the interlayer enables an initial discharge capacity of about 8.5 mAh cm−2 (for a total sulfur mass loading of 10 mg cm−2) and a discharge capacity retention of about 64 % after 700 cycles at 335 mA g−1 and 25 °C.