A Library of Polymetallic Alloy Nanotubes: From Binary to Septenary

The polymetallic alloy nanostructure has received widespread attention in electrocatalytic reactions due to the variability in composition and excellent performance. However, the controllable synthesis of one-dimensional (1D) polymetallic alloy nanomaterials remains a significant challenge. Herein, we propose a new and general low-temperature method to prepare a library of binary to septenary polymetallic alloy nanotubes, and this method can be used to synthesize 18 kinds of polymetallic alloy nanotube (NT), including eight kinds of high-entropy alloy (HEA) NT. A representative Cu₃₀Ni₂₆Co₁₉Ru₁₄Ir₁₁ HEA NT demonstrates efficient and stable catalytic performance for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The Cu₃₀Ni₂₆Co₁₉Ru₁₄Ir₁₁ HEA NT exhibits an overpotential of only 121 mV for the HER and 272 mV for the OER, respectively, when measured at a current density of 100 mA cm^-2. In addition, the two-electrode system comprising the Cu₃₀Ni₂₆Co₁₉Ru₁₄Ir₁₁ HEA NT exhibits an impressive efficiency of 100 mA cm^-2 during overall water splitting, requiring only a potential of 1.67 V. The high catalytic activity of the Cu₃₀Ni₂₆Co₁₉Ru₁₄Ir₁₁ HEA NT is attributed to the downward shift of the d-band center. In the HER, the downward shift of the d-band center can reduce the binding energy with *H, which is beneficial for the desorption process of hydrogen. In the OER, the downward shift can also reduce the reaction energy barrier associated with the rate-determining step from *O to *OOH. This work seeks to offer a new and general method for synthesizing polymetallic alloy nanotubes with controllable structures and compositions under mild conditions.