Heterostructure CoS2/MoS2 Nanosheets as a Dual-Active Electrocatalyst for the Oxygen Evolution Reaction.

Cost-effective and earth-abundant oxygen evolution reaction (OER) electrocatalysts are an incredible research hotspot in numerous energy storage and conversion technology fields. Herein, CoS2/MoS2 nanosheets supported by carbon cloth as a dual-active CC@CoS2/MoS2 heterostructure electrocatalyst is prepared through a simple solvothermal method. The catalyst demonstrates admirable OER performance in 1 M KOH solution with a low overpotential of 243 mV at a current density of 10 mA cm-2 and a minor Tafel slope of 109 mV dec-1, displaying honorable stability after 1000 cyclic voltammetry (CV) cycles and long-term robustness over 60 h. Theoretical calculations further ascertain that the rate-determining step of the electrocatalytic course of the CC@CoS2/MoS2 heterostructure is the conversion *O + OH- → *OOH + e- with a lower energy barrier of 1.49 eV due to the heterojunction established by CoS2 and MoS2, which can promote the OER performance of electrocatalysts. The actual identification of the catalytic mechanism in the heterostructure is conducive to the improvement of electrocatalysis applications in the OER.

Polynitro-acetone, dimethyl ether, and dimethylamine: a series of potential green and powerful oxidants for propellants.

With the purpose of searching novel, green and energetic oxidants, polynitro-acetone, polynitro-dimethyl ether, and polynitro-dimethylamine are designed as potential powerful oxidants and energetic materials in this work. Their optimized molecular geometries and electronic structures are calculated using density functional theory at m062x/6-311G++(d,p) level. Based on these results, heat of formation (HOF), detonation energy (Q), detonation velocity (D), and detonation pressure (P) are further evaluated. It is found that the oxygen-rich and chlorine-free compounds with 5 to 6 NO2 groups in molecule can be used as the potential energetic oxidants with high oxygen balance, while those with 3 to 4 NO2 groups are suitable for high-density energetic materials. Furthermore, stability correlations of all the compounds are established according to calculated bond order, natural bond orbital (NBO), bond dissociation enthalpies (BDE), and energy gaps (ΔELUMO-HOMO). Finally, burning rate is also calculated to show their potential application as oxidants in propellants. Graphical abstract.