The A15 structure of superconductors is a prototypical type-II superconductor that has generated considerable interest since the early history of superconducting materials. This paper discusses the superconducting properties of previously unreported V3−xCoxSi (0 ⩽ x ⩽ 0.30) alloys. It is found that the lattice parameter decreases with increasing cobalt-doped content and leads to an decreased residual resistivity ratio value of the V3−xCoxSi system. Meanwhile, the superconducting transition temperature (Tc) also decreases with increasing cobalt-doped content. Furthermore, the fitted data show that the increase of cobalt-doped content also reduces the lower/upper critical fields of the V3−xCoxSi system. Type-II superconductivity is demonstrated in all V3−xCoxSi samples. With higher Co-doped content, V3−xCoxSi (0.15 ⩽ x ⩽ 0.30) alloys may have superconducting and structural phase transitions in low-temperature regions. As the electron/atom ratio increases, the Tc variation trend of V3Si is as pronounced as in crystalline alloys and monotonically follows the trend observed for amorphous superconductors.
Exploring high-efficiency and low-cost electrocatalysts is valuable for water-splitting technologies. Recently, Si-group compounds have attracted increasing attention in electrocatalysis, considering the abundant Si-group elements on Earth. However, Si-group compounds for HER electrocatalysis have not been systematically studied. In this study, we unveil the activity trends of non-noble metal catalyst A15-type V 3 M ( i.e. , V 3 Si, V 3 Ge, and V 3 Sn) superconductors and show that V 3 Si is the most efficient HER catalyst because of the high electronic conductivity and suitable d -band center. Among them, the V 3 Si only requires 33.4 mV to reach 10 mA cm −2 , and only 57.6 mV and 114.6 mV are required to attain a high current density of 100 mA cm −2 and 500 mA cm −2 , respectively. These low overpotentials are close to the 34.3 mV at 10 mA cm −2 of state-of-art Pt/C (20 %) but superior to 168.5 mV of Pt/C (20 %) at 100 mA cm −2 . Furthermore, the V 3 Si illustrates exceptional durability with no obvious decay in the 120 h at the different current densities ( i.e. , 10–250 mA cm −2 ). The excellent HER activity of V 3 Si alloy can be ascribed to the synergies of superior electronic conductivity and suitable d -band center. Moreover, DFT calculations reveal that |ΔG H* | is decreased after introducing the V to Si. Beyond offering a stable and high-performance electrocatalyst in an acidic medium, this work inspires the rational design of desirable silicide electrocatalysts .
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