The DSC-TG-MS-FTIR coupling technique and in situ FTIR technique were used to study the catalytic effects of nano-Fe2O3 and rGO–Fe2O3 on the thermal decomposition behaviors of CL-20/HMX cocrystals. The results showed nano-Fe2O3 having a good catalytic effect on the thermal decomposition of the CL-20/HMX cocrystal. Nano-Fe2O3 was found to enhance CO2 production and prevent the production of NH2+, HCN, and CHO or N2H+ during the decomposition of cocrystalline CL-20/HMX. Meanwhile, both the CL-20/HMX thermal decomposition peak temperature and Ea were reduced by including nano-Fe2O3. The inclusion of rGO–Fe2O3 did not enhance the catalytic effect of nano-Fe2O3, but did reduce residue formation during the CL-20/HMX decomposition process. Breaking of N–N bonds and the release of NO2 were concluded to constitute the initial steps of the decomposition of the CL-20/HMX cocrystal. This investigation has contributed to our understanding of the thermal decomposition of the CL-20/HMX cocrystal and provides guidance for the catalytic decomposition of energetic material cocrystals.
Developing high activity, low-cost and long durability catalysts for oxygen reduction reaction is of great significance for the practical application of microbial fuel cells. The full exposure of active sites in catalysts can enhance catalytic activity dramatically. Here, novel Fe-N-doped graphene is successfully synthesized via a one-step in situ ball milling method. Pristine graphite, ball milling graphene, N-doped graphene and Fe-N-doped graphene are applied in air cathodes, and enhanced performance is observed in microbial fuel cells with graphene-based catalysts. Particularly, Fe-N-doped graphene achieves the highest oxygen reduction reaction activity, with a maximum power density of 1380±20 mW/m 2 in microbial fuel cells and a current density of 23.8 A/m 2 at −0.16 V in electrochemical tests, which are comparable to commercial Pt and 390% and 640% of those of pristine graphite. An investigation of the material characteristics reveals that the superior performance of Fe-N-doped graphene results from the full exposure of Fe 2 O 3 nanoparticles, pyrrolic N, pyridinic N and excellent Fe-N-G active sites on the graphene matrix. This work not only suggests the strategy of maximally exposing active sites to optimize the potential of catalysts but also provides promising catalysts for the use of microbial fuel cells in sustainable energy generation.
Transition metal-based catalysts possess high catalytic activity for oxygen evolution reaction (OER). However, the preparation of high-performance OER electrocatalysts using simple strategies with a low cost still faces a major challenge. Herein, this work presents an innovative, in situ-induced preparation of the Fe 2 O 3 , FeS, and NiS nanoparticles, supported on carbon blacks (CBs) (denoted as Fe 2 O 3 -Fe(Ni)S/C) as a high-efficiency oxygen evolution electrocatalyst by employing biomineralization. Biomineralization, a simple synthesis strategy, demonstrates a huge advantage in controlling the size of the Fe 2 O 3 and Fe(Ni)S nanoparticles, as well as achieving uniform nanoparticle distribution on carbon blacks. It is found that the electrocatalyst Fe 2 O 3 -Fe(Ni)S/C-200 shows a good OER electrocatalytic activity with a small loading capacity, and it has a small overpotential and Tafel slope in 1 m KOH solution with values of 264 mV and 42 mV dec −1 , respectively, at a current density of 10 mA cm −2 . Additionally, it presents good electrochemical stability for over 24 h. The remarkable and robust electrocatalytic performance of Fe 2 O 3 -Fe(Ni)S/C-200 is attributed to the synergistic effect of Fe 2 O 3 , FeS, and doped-Ni species as well as its distinct 3D spherical structure. This approach indicates the promising applications of biomineralization for the bio-preparation of functional materials and energy conversion.
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