With the help of marine alginate, Zn(OH) 2 nanorods were synthesized under mild conditions (e.g., room temperature and atmospheric pressure) through a one-step, green, and scalable method, in which both the morphologies (e.g., nanorods and nanoflakes) and nanoscale sizes of Zn(OH) 2 could be precisely controlled by alginate. Considering the high reactive activity as well as the adhesion property of dopamine, polydopamine nanotubes were produced by the template of Zn(OH) 2 rods and following a mussel-biomimetic strategy of dopamine coating. The enhanced activities of polydopamine surfaces further offered the possibility of embedding Ag nanoparticles to produce Ag nanotubes with super-catalytic and -antibacterial properties. The combination of inexpensive starting materials, simple synthesis procedure, and exceptional properties gives Zn(OH) 2 rods/nanoflakes great potential as templates and for multiple applications in catalysis, sensing, etc.