Rational entry-diffusion induced Kirkendall effect towards Au₂S nanotubes

Semiconductor nanotubes manifesting large surface area, high tensile strength, light weight, fast electron transfer kinetics and high biocompatibility have attracted tremendous attention and find widespread applications. Rational design and preparation of semiconductor nanotubes with such a unique morphology to maximum their performance and therefore, to fulfill their applications is still a challenge. Herein, we report a strategy that is capable of rationalizing entry-diffusion of Au ⁺ ions into Cu_2-xS nanorods based on the Kirkendall effect, accomplishing consecutive morphology control from solid nanorods to nanotubes, and ultimately to nanorings of Au₂S. The structure and composition of Au₂S nanotubes were further confirmed through X-ray photoelectron spectroscopy, annular bright-field scanning transmission electron microscopy-energy dispersive spectroscopy and scanning transmission electron microscopy and Aberration-corrected transmission electron microscopy. Compared with nanorods, Au₂S nanotubes demonstrated significantly enhanced catalytic activity in electrocatalytic hydrogen evolution reaction, a remarkably low overpotential of 602.0 mV at a current density of −10 mA cm⁻² and a relatively low Tafel slope of 36.87 mV dec⁻¹ in 0.5 M H₂SO₄ solution. It is anticipated that this novel strategy of mediating ion diffusion rate would inspire rational control of unique morphologies and structures of semiconductor nanocrystals, providing a platform for further applications based on nanomaterials.