The CuFe<sub>2</sub>O<sub>4</sub>@SiO<sub>2</sub>@ZrO<sub>2</sub>/SO<sub>4</sub><sup>2−</sup>/Cu nanoparticles: an efficient magnetically recyclable multifunctional Lewis/Brønsted acid nanocatalyst for the ligand- and Pd-free Sonogashira cross-coupling reaction in water
RSC advances