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Exploring efficient, low-cost electrocatalysts is critical for improving the efficiency of water splitting reactions. Noble-metal-based oxides exhibit high activities in the oxygen evolution reaction (OER). However, their high cost and the lack of natural resources hinder their practical application. Therefore, in this study, we successfully synthesized an FeCoNiMgB high-entropy boride powder via a facile chemical reduction method for use as an OER catalyst in an alkaline medium. The FeCoNiMgB powder, with an ultrathin fluffy cotton structure, exhibited an excellent OER catalytic performance, affording an overpotential of 268 mV at a current density of 10 mA/cm2and a low Tafel slope of 42.9 mV/dec; this performance was superior to those of FeCoNiB, FeNiMgB, CoNiMgB, FeCoMgB, and commercial RuO2. The FeCoNiMgB powder also displayed remarkably stable catalytic properties for >72 h with no clear evidence of degradation. Finally, using theoretical calculations, the excellent OER performance of FeCoNiMgB was verified in terms of its adsorption and charge transfer energies and covalence. The performance and stability of FeCoNiMgB were equivalent or superior to those of several nanostructured catalysts, and thus, this study provided valuable insight into the design of efficient high-entropy boride materials.

A novel strategy for condition assessment of concrete piers subjected to impact load is presented in this article. The method of estimating residual displacement (lateral displacement and rotation angle) of concrete piers using long-gauge fiber optic sensing is firstly established. Theoretical derivation reveals that there exists linear relationship between the residual average strain and lateral displacement or rotation angle of the concrete piers. Then, a scaled concrete pier subjected to impact load was designed to verify the condition assessment strategy. The damages of the pier gradually increase by changing the impact velocity of the moving vehicle. Experimental results show that the residual average strain can well reflect the location and severity of random crack damages of the pier under impact load. Meanwhile, residual lateral displacement and rotation angel distribution along the specimen can be identified using the residual average strain measured by long-gauge fiber optic sensors. In addition, hammer excitation was also conducted on the pier after each impact in order to obtain structural dynamic properties. The extracted natural frequencies can reflect global performance (boundary condition and global stiffness) of the pier at each damage state. Therefore, the presented strategy could be a new alternative for condition assessment of concrete piers or columns in civil engineering.