Graphene-Directed Synthesis of Bicontinuous Core/Shell and Tubular Metal Nanostructures for Battery Electrodes

Nanoporous metals with bicontinuous architecture offer attractive scaffolds for energy storage and catalysis, yet their limited porosity and structural tunability hinder broader applications. Here, a graphene-directed strategy is reported to construct hierarchical core/shell Ni/NiO and tubular metal nanostructures via controlled oxidation of nanoporous Ni. A conformal graphene coating stabilizes the underlying framework and governs oxidation through a product-layer diffusion-controlled shrinking-core mechanism. This enables the formation of tunable core/shell and hollow tubular architectures with exceptional porosity (up to ≈86%), controllable shell thickness, and well-preserved bicontinuous morphology over macroscopic scales. As electrodes for Li-ion batteries, the core/shell Ni/NiO exhibits a high reversible capacity (≈750 mAh g^-1) and excellent cycling stability. Meanwhile, the reduced and displaced tubular Ru serves as a high-performance, carbon-free cathode for Li-O₂ batteries, demonstrating low charge overpotentials, high energy efficiency (≈78%), and prolonged cycling over 200 cycles. This work offers a general and scalable route to engineer functional porous architectures with programmable structure and composition, holding broad promise for next-generation energy systems and beyond.