The highly dispersed Co-based nanoparticles encapsulated into porous N-doping carbon polyhedral with the low content of Ru modification as a promising cathode catalyst for long-life Li-O_(2)batteries

Lithium(Li)-O_(2)batteries have triggered worldwide interest due to their ultrahigh theoretical energy density.However,it is a long shot for the grand-scale applications of Li-O_(2)battery at current stage owing to its significant polarization,inferior cycling life,and irreversible decomposition of Li2O_(2).Herein,a facile way of preparing the highly dispersed Co-based nanoparticles encapsulated into porous N-doping carbon polyhedral with the low content of Ru modification(LRu@HDCo-NC)is explored through the pyrolysis of Co/Zn based zeolitic imidazole frameworks(ZIFs)containing Ru-based ligands.Even with the very small amount of Ru introduction(1.8%),LRu@HDCo-NC still exhibits the superior oxygen evolution reaction/oxygen reduction reaction(OER/ORR)performance and also inhibits side reactions in Li-O_(2)battery because of the abundant pores,plentiful surface N heteroatoms,and highly dispersed metal-based sites which are induced by the volatilization of Zn,and conductive/stable carbon skeleton derived from ZIFs.When applied in Li-O_(2)batteries,LRu@HDCo-NC cathode delivers a high discharge capacity of 15,973 mAh·g^(-1)at 200 mA·g^(-1),good capacity retention at higher rate(12,362 mAh·g^(-1)at 500 mA·g^(-1))and outstanding stability for>300 cycles with low voltage polarization of<2.3 V under a cut-off capacity of 1,000 mAh·g^(-1)at 500 mA·g^(-1).More critically,a series of ex situ and in situ characterization technologies disclose that the LRu@HDCo-NC cathodes can effectively promote the reversible reactions in Li-O_(2)batteries.

Ruthenium-modified porous NiCo2O4 nanosheets boost overall water splitting in alkaline solution

Exploring efficient oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)electrocatalysts is crucial for developing water splitting devices.The composition and structure of catalysts are of great importance for catalytic performance.In this work,a heterogeneous Ru modified strategy is engineered to improve the catalytic performance of porous NiCo_(2)O_(4)nanosheets(NSs).Profiting from favorable elements composition and optimized structure property of decreased charge transfer barrier,more accessible active sites and increased oxygen vacancy concentration,the Ru-NiCo_(2)O_(4)NSs exhibits excellent OER activity with a low overpotential of 230 mV to reach the current density of 10 mA/cm^(2)and decent durability.Furthermore,Ru-NiCo_(2)O_(4)NSs show superior HER activity than the pristine NiCo_(2)O_(4)NSs,as well.When assembling Ru-NiCo_(2)O_(4)NSs couple as an alkaline water electrolyzer,a cell voltage of 1.60 V can deliver the current density of 10 mA/cm^(2).This work provides feasible guidance for improving the catalytic performance of spinel-based oxides.