Despite promising characteristics such as high specific energy and low cost, current Li-S batteries fall short in cycle life. Improving the cycling stability of S cathodes requires immobilizing the lithium polysulfide (LPS) intermediates as well as accelerating their redox kinetics. Although many materials have been explored for trapping LPS, the ability to promote LPS redox has attracted much less attention. Here, we report for the first time on transition metal phosphides as effective host materials to enhance both LPS adsorption and redox. Integrating MoP-nanoparticle-decorated carbon nanotubes with S deposited on graphene oxide, we enable Li-S battery cathodes with substantially improved cycling stability and rate capability. Capacity decay rates as low as 0.017% per cycle over 1, 000 cycles can be realized. Stable and high areal capacity (> 3 mAh·cm^-2) can be achieved under high mass loading conditions. Comparable electrochemical performance can also be achieved with analogous material structures based on CoP, demonstrating the potential of metal phosphides for long-cycle Li-S batteries.

Rational design and controlled fabrication of efficient and cost-effective electrodes for the oxygen evolution reaction (OER) are critical for addressing the unprecedented energy crisis. Nickel–iron layered double hydroxides (NiFe-LDHs) with specific interlayer anions (i.e. phosphate, phosphite, and hypophosphite) were fabricated by a co-precipitation method and investigated as oxygen evolution electrocatalysts. Intercalation of the phosphorus oxoanion enhanced the OER activity in an alkaline solution; the optimal performance (i.e., a low onset potential of 215 mV, a small Tafel slope of 37.7 mV/dec, and stable electrochemical behavior) was achieved with the hypophosphite-intercalated NiFe-LDH catalyst, demonstrating dramatic enhancement over the traditional carbonate-intercalated NiFe-LDH in terms of activity and durability. This enhanced performance is attributed to the interaction between the intercalated phosphorous oxoanions and the edge-sharing MO₆ (M = Ni, Fe) layers, which modifies the surface electronic structure of the Ni sites. This concept should be inspiring for the design of more effective LDH-based oxygen evolution electrocatalysts.