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Efficient CO 2 electrodes require optimized catalytic activity and a delicate electrode structure. However, it is often insufficient to consider only a single factor when constructing a high-performance electrode. In this study, we elaborately prepare the freestanding Fe-doped CoP catalysts on N-doped carbon cloth (Fe-CoP@N-CC) substrates, which synergistically realizes electronic structure tuning of the catalysts and electrode structure modification. The experimental and theoretical calculations reveal that the electrode structure, consisting of fully covered nanowires on an N-CC skeleton, promotes mass transfer and accommodates products. The introduction of N atoms in Fe-CoP@N-CC leads to increased defects and strong Co–N–C bonds at the interface, enhancing interfacial electron transfer. Furthermore, Fe doping optimizes the electronic structure of Fe-CoP@N-CC. This synergistic enhancement facilitates the kinetics of both CO 2 reduction reaction (CO 2 RR) and CO 2 evolution reaction (CO 2 ER), resulting in the formation of large-size spherical morphologies following the solution pathway. The improved electrocatalytic performance of Fe-CoP@N-CC electrodes was demonstrated by their high discharge capacity of 4127 mAh g−1 and cycling stability of 446 h in Li–CO 2 batteries. These findings emphasize the significance of compatibility between electrode structure and catalytic activity in the design of CO 2 electrode. • Fe-doped CoP on N-doped carbon cloth (Fe-CoP@N-CC) substrates were fabricated. • Enlarged reaction active area and promoted mass transfer. • Strong Co–N–C bonds at the interface can facilitate interfacial electron transfer. • Enhanced CO 2 RR and CO 2 ER kinetics are realized. • Optimizing morphology and discharge product pathways. [ABSTRACT FROM AUTHOR]

We propose and experimentally demonstrate an optical fiber torsion sensor based on symmetrically polished single-multi-single mode (SP-SMS) fiber structure. The polished structure enhances the torsion response effectively, which is fabricated by a high-frequency CO 2 laser. Experimental results show that the high sensitivity of the proposed torsion sensor reaches 1.032 nm/(rad m−1) in the range from − 10.261 rad/m to 10.261 rad/m. Meanwhile, the temperature response of the sensor is also investigated, which is 21 pm/°C in the range from 30 °C to 150 °C. Moreover, the structure has the features of low cost, simple fabricating method and small temperature crosstalk. Schematic diagram of the symmetrically polished SMS fiber structure (SP-SMS). The geometrical shape of the sensor is prepared by a high-frequency CO 2 laser, which enhances the torsion sensitivity of the structure. The structure achieves a high sensitivity of 1.032 nm/(rad m−1). Meanwhile, small temperature-torsion crosstalk of 0.03 (rad m−1)/°C is achieved. The fabricating method of the structure has the advantages of is non-contact and scalable. Hence, the proposed structure provides a new idea to the design of the fiber torsion sensor. [Display omitted] • The highest torsion sensitivity of the SP-SMS reaches to 1.032 nm/(rad m−1). • The low temperature-torsion crosstalk is obtained, which is 0.03 (rad m−1)/°C. • Low cost, compact structure and easy fabrication. [ABSTRACT FROM AUTHOR]

In this paper, we developed and experimentally evaluated a new type of long-period fiber grating. This structure is fabricated by CO 2 laser polishing and subsequent heating with an oxyhydrogen flame. Firstly, a single-mode fiber is produced using a high-frequency CO 2 laser to form periodic trapezoidal structures. It is then heated with an oxyhydrogen-flame-based fiber optic tapering system to bend the core slightly toward the polished area. The micro-bent cores exhibit strong refractive index modulation, which make the core-modulated LPFG more sensitive to tensile strain. The experimental results show that the proposed sensor exhibits a strain sensitivity as high as 30.43 pm/ μ ε over the 0–100 μ ε range and a temperature sensitivity of 9.29 pm/ ∘ C. Based on the results of a general theoretical analysis and simulations, we attribute the threshold point of its strain sensitivity to the degree of micro-bending of the core. Furthermore, the structure is low cost and compact and exhibits high mechanical strength and thus can be used in a variety of applications in several fields. • A new method for fabricating LPFGs is proposed and experimentally demonstrated. • The microbent core exhibits strong refractive index modulation, which makes the core-modulated LPFG more sensitive to tensile strain. • The strain sensitivity of the fabricated CM-LPFG is as high as 30.43 pm/ μ ε for the 0–100 μ ε. • Low cost, compact size, high mechanical strength. [ABSTRACT FROM AUTHOR]

• A high sensitive curvature optical fiber sensor is achieved by using CO 2 laser polished method. • The highest bending sensitivity of the AP-LPFG reaches to 30.85 nm/m−1. • A compact length is obtained, which is 7.39 mm. • Low cost, simple structure and easy fabrication. In this paper, we experimentally propose and theoretically investigate a two-dimensional vector curvature sensor based on asymmetrically polished long period fiber grating (AP-LPFG). This sensor is fabricated by a high-frequency CO 2 laser in order to polish periodic asymmetrical V-shaped grooves on a single mode fiber (SMF). Such grooves efficiently enhances the bending sensitivity of sensor and shorten the length of the structure to 7.39 mm. Experimental results show that the sensitivity of AP-LPFG reaches 30.85 nm/m−1 in the direction of the X-axis and −0.97 nm/m−1 in the direction of the Y-axis. Meanwhile, the temperature response of AP-LPFG is carried out, which is 76 pm/℃ in range of 30-160℃. Moreover, the AP-LPFG has the features of compact length and simple structure, which shows the potential in curvature sensing. [ABSTRACT FROM AUTHOR]