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[Display omitted] • Four diameters of 3DOM-FeCo 2 O 4 were prepared using PMMA as a template. • 3DOM-FeCo 2 O 4 as catalyst can obviously accelerate the thermal decomposition of AP. • 215 nm 3DOM-FeCo 2 O 4 /Al has the best heat release and ignition characteristic. To improve the combustion performance of solid propellants relies on efficient combustion catalyst with large specific surface area and high density of active sites. In this work, three-dimensional ordered macroporous FeCo 2 O 4 (3DOM - FeCo 2 O 4) with four different pore diameters was successfully prepared using polymethyl methacrylate (PMMA) colloidal crystals as a template. Differential scanning calorimetry (DSC) study shows that 3DOM - FeCo 2 O 4 with a pore diameter of 176 nm has the best catalytic performance on the thermolysis of ammonium perchlorate (AP). The decomposition peak temperature and apparent activation energy were reduced by 116.5 ℃ and 26.1 kJ/mol, respectively. Thermogravimetry/mass spectrometry (TG/MS) was used to analyze the catalytic mechanism. The result indicates that 3DOM-FeCo 2 O 4 can accelerate the electron transfer from ClO 4 – to NH 4 + to form HClO 4 and NH 3 and the transformation from O 2 to superoxide ion(O 2 –), thus providing active sites for intermediate products of AP and catalyzing the decomposition of AP. Furthermore, the heat release and ignition tests of thermites using 3DOM-FeCo 2 O 4 as the oxidant were carried out. The thermite with a pore diameter of 215 nm exhibits higher heat release and better ignition characteristic compared to the thermites with other pore diameters. [ABSTRACT FROM AUTHOR]

LaFeO 3 @MnO 2 with core-shell structure shows an efficiently catalytic effect for the thermal decomposition of energetic compounds. • The core-shell structured LaFeO 3 @MnO 2 was synthesized using solvothermal method. • The special core-shell structure provides high dispersibility and large surface area. • The produced charge carriers in LaFeO 3 @MnO 2 can accelerate the thermolysis of AP. • LaFeO 3 @MnO 2 shows excellent catalytic effects on thermolysis of energetic compounds. Large particle size and low specific surface area are two major factors of restricting metal oxides as combustion catalyst with high performance. The construction of three-dimensional (3D) heterojunction materials with synergistic effect is conducive to enhancing the catalytic activity. In this work, LaFeO 3 were prepared by a facile solvo-thermal method and post-heat treament. However, the LaFeO 3 with a large particle size shows poor specific surface area, resulting in a low catalytic activity. In order to improve its catalytic activity, a 3D core/shell heterostructured LaFeO 3 @MnO 2 composite was constructed by coupling LaFeO 3 with MnO 2. The core-shell structured LaFeO 3 @MnO 2 provides a larger specific surface area and high catalytic effect on the thermal decomposition of ammonium perchlorate (AP) with a reduced decomposition temperature from 403.73 °C to 281.38 °C, an enhanced energy release from 649.6 J·g−1 to 966.5 J·g−1, and a decreased apparent activation energy from 139.05 kJ·mol−1 to 110.88 kJ·mol−1. Additionally, LaFeO 3 @MnO 2 also shows efficient catalytic effects on the thermal decomposition of hexanitrohexaazaisowurzitane (CL-20) and cyclotetramethylenetetranitramine (HMX). [ABSTRACT FROM AUTHOR]

Metal oxides/graphene composites are potential solid propellant combustion catalysts owing to their complementary property between two components. Herein, an in-situ growth method was used for preparing γ-Fe 2 O 3 /graphene composites (γ-Fe 2 O 3 /G) with intimately coupled graphene sheets and flowerlike γ-Fe 2 O 3 nanoparticles (NPs). The in-situ growth strategy can not only inhibit the aggregation of γ-Fe 2 O 3 NPs, but also reduce the particle size of γ-Fe 2 O 3. As an efficient catalyst for the thermal decomposition of hexanitrohexaazaisowurtzitane (CL-20), γ-Fe 2 O 3 /G2 (2 represents the graphene concentration is 2 mg/mL) decreases the thermal decomposition temperature of CL-20 from 252.13 °C to 245.20 °C and the apparent activation energy from 183.02 kJ/mol to 150.68 kJ/mol, respectively. The improved catalytic activity may be attributed to the synergistic effect between γ-Fe 2 O 3 and graphene, which can efficiently construct the three-dimensional framework structure for exposing more active sites. [ABSTRACT FROM AUTHOR]

Abstract Bifunctional electrocatalysts for overall water splitting in acidic media is critical for polymer electrolyte membrane (PEM) electrolysis of water. We report a synthesis of porous carbon-coated noble metal-based catalysts. We adopt simple annealing strategy involving Ir-doped zeolite imidazole skeleton to obtain IrCo alloys encapsulated by the porous carbon layers and carbon nanotubes, which is a new method for synthesizing IrCo alloy. The amount of Ir loaded in IrCo NPs catalyst is extremely low (only 6.7 wt%) and IrCo NPs exhibit excellent catalytic activity for both HER and OER in acidic environment, to achieve 10 mA cm−2 current density during HER and OER, overpotential of only 23.9 and 270 mV is required for our novel IrCo NPs catalyst. More significantly, IrCo NPs reach 10 mA cm−2 during overall water splitting at a cell voltage of only 1.55 V in 0.5 M H 2 SO 4 and demonstrated good durability. Thus, it has excellent prospects to be implemented into PEM for water electrolysis. [ABSTRACT FROM AUTHOR]