Da-Jiang Liu , Jie Zhang , Long Qi , James W. Evans
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引用次数: 0
Abstract
Machine learning (ML)-based molecular dynamics (MD) simulations of the formation of a class of N-doped nanoporous carbons are performed to assess their disordered partially graphitized nanoscale structure. The study is motivated by the effectiveness of so-called nitrogen assembly carbons (NACs) for catalysis applications. Benchmark simulations for pure-C disordered graphitic systems reveal the importance of reliably capturing the vdW component of the potentials in order to accurately describe the tendency for layering of disordered graphene-like sheets. In our modeling, this is achieved by a transfer learning strategy incorporating features of the energetics from the optB88-vdW DFT functional into potentials initially trained with a less expensive functional, thereby providing a superior description of the pure-C systems. Generation from MD simulations of realistic partially graphitized structures is significantly more challenging for N-doped versus for pure C systems. However, such structures are achieved by a tailored MD simulation protocol mimicking the experimental synthesis process and in particular incorporating an annealing and subsequent quenching stages. Simulated PXRD patterns effectively reproduce the features of experimental observations for NACs, including the appearance of a prominent but broad (002) peak at around 25, and the development of another weaker feature associated with in-layer ordering of mixed C-N graphene-like sheets.
期刊介绍:
The journal Carbon is an international multidisciplinary forum for communicating scientific advances in the field of carbon materials. It reports new findings related to the formation, structure, properties, behaviors, and technological applications of carbons. Carbons are a broad class of ordered or disordered solid phases composed primarily of elemental carbon, including but not limited to carbon black, carbon fibers and filaments, carbon nanotubes, diamond and diamond-like carbon, fullerenes, glassy carbon, graphite, graphene, graphene-oxide, porous carbons, pyrolytic carbon, and other sp2 and non-sp2 hybridized carbon systems. Carbon is the companion title to the open access journal Carbon Trends. Relevant application areas for carbon materials include biology and medicine, catalysis, electronic, optoelectronic, spintronic, high-frequency, and photonic devices, energy storage and conversion systems, environmental applications and water treatment, smart materials and systems, and structural and thermal applications.