A Library of Polymetallic Alloy Nanotubes: From Binary to Septenary

Abstract

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 <i>d</i>-band center. In the HER, the downward shift of the <i>d</i>-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.