The enrichment of nanoscale zero-valent iron particles (nZVI) in spatially confined nanostructures with controllable active sites is challenging but has significant effects in environmental remediation. Here, various Fe@PMO nanostructures with well-designed site-exposure of iron are fabricated for investigation of the recovery behaviour of metals. It was found that the Fe@PMO Janus nanoparticles show rapid enrichment of Au(iii) in 10 min, reaching ∼71%, and the optimal removal efficiency can be close to ∼98%.