Ion‐Induced Synthesis of Uniform Single‐Crystalline Sulphide‐Based Quaternary‐Alloy Hexagonal Nanorings for Highly Efficient Photocatalytic Hydrogen Evolution

: Uniform single-crystalline quaternary sulphide nanoring photocatalysts are synthesized via the copper-ion-induced Kirkendall effect and is followed by a cation exchange reaction. The obtained Cu(2+)-doped ZnIn(2)S(4) nanorings show highly preserved morphology, and demonstrate high visible-light-driven photocatalytic activity for H(2) evolution in water splitting.