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In this work, a simple, controllable and mass-produced microcrack technique for stretchable strain sensors is presented. Specifically, the conductive layer (hydroxylated MWCNTs) and the flexible substrate (Ecoflex) of fiber strain flexible sensors are modified based on proton irradiation defect engineering. The evolution of defects in sensitive materials and the density of microcracks in flexible substrates are controlled by controlling the irradiation fluence during the irradiation process. In particular, when the irradiation fluence is 1 × 1014 p cm−2, the gauge factor (GF) of the fiber strain sensor is as high as 1274.8, and the response time and recovery time are reduced by 49.4% and 45.1%, respectively. At the same time, the microcracked structure does not fracture easily under a large strain, the maximum strain being 800%. In addition, fiber strain flexible sensors can also be used to detect biomechanical signals in different scenarios. This simple and efficient microcrack technique opens up a new prospect for the fabrication of high-performance stretchable strain sensors. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) with its low cost, excellent electrochemical stability and large specific surface area is expected to replace noble metals such as platinum as a new type of high-efficiency electrocatalyst. Since it is very difficult to effectively improve the catalytic performance only from intrinsic materials, we used the 60Co γ-ray as the irradiation source to modify thin layer MoS2 nanosheets (MoS2 NSs), and explore the irradiation effect and the mechanism of catalytic performance improvement. The structure–activity relationship was investigated in depth by characterizing the morphology and structure of MoS2 NSs before and after γ-ray irradiation, combined with the changes in HER performance. The results show that the irradiation-induced defects are dominated by sulfur (S) vacancies, which can efficiently regulate the intrinsic electronic structure of MoS2 NSs. The introduction of defects increases the number of active sites on the surface of nanosheets and improves the reaction kinetics, optimizing the hydrogen evolution reaction (HER) performance. When the irradiation dose is too large, we reveal that the oxygen atoms passivate the S vacancies in the MoS2 NSs and cause the concentration of S vacancies to decrease, resulting in the reduction of electrocatalytic performance. It is concluded that the appropriate irradiation dose is the key factor to improve the HER performance of MoS2 NSs. [ABSTRACT FROM AUTHOR]