**Configuration defects-induced energy loss of a self-shrinking
nanonetwork under cyclic biaxial stretching-shrinking**

ZX Zhang and K Cai and L Wang, COMPUTATIONAL MATERIALS SCIENCE, 227, 112280 (2023).

DOI: 10.1016/j.commatsci.2023.112280

Using the molecular dynamics method, we studied the stored energy density (SED) of the nanonetwork made from hydrogenated graphene ribbons (HGRs) under biaxial stretching-shrinking repeats. Since the HGRs work as springs, the network tends to self-shrink when stretched. Hence, the potential energy is released after stretching and is stored after shrinking. However, shrinking of the insufficiently stretched HGRs may lead to redistribution of the ribbons in the network that cannot recover to their initial state due to local defects appearing in the shrinking of the stretched nanostructure. Then, the defects lead to a reduction of the network's capacity for energy storage. In this study, the defects- induced energy loss of the network under a biaxial stretching is esti- mated by considering some essential factors, e.g., the ratio of the two stretching speeds, the length of HGRs, and the number of cycles (c) of the biaxial stretching-shrinking process. Some conclusions are drawn for potential applications of nanonetwork. It is discovered that in the cyclic stretching-shrinking process, some defects generated in the first several repeats gradually disappear, i.e., the network behaves self- healing. After the first several times (e.g., 7 times in this study) of cyclic stretching-shrinking, the distribution of the HGRs in the network becomes uniform or even periodic. Hence, the network can work with high robustness in dynamic devices, e.g., resonators or oscillators.

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