AAO Template-Assisted Fabrication of Vertically Ordered Triangular Pt/Ni Nanopillar Arrays for Enhanced Hydrogen Evolution Reaction

Vertically ordered nanopillar (NP) arrays with sharp nanoedges are attractive for electrocatalytic hydrogen evolution reaction (HER) because the vertically ordered architecture provides efficient transport pathways and large accessible surface areas, while the sharp nanoedges enhance local electric fields and current densities. However, the fabrication of such vertically ordered nanostructures with sharp nanoedges remains challenging. Here, we report an anodic aluminum oxide (AAO) template-assisted strategy to construct vertically ordered triangular Pt/Ni NP arrays with sharp nanoedges for enhanced HER activity. To demonstrate the advantages of triangular NPs, circular Pt/Ni NPs with similar dimensions, composition, Pt chemical states and crystalline phases, and core–shell structures were also fabricated by the same AAO template-assisted strategy as a control to investigate the geometric effect. Electrochemical measurements demonstrate that the triangular NPs exhibit 35% higher HER activity at −100 mV vs. RHE compared to their circular counterparts. Furthermore, COMSOL (Multiphysics 5.5) simulations reveal that the sharp nanoedges induce locally enhanced electric fields and current densities, providing critical insight into the geometry-dependent electrochemical enhancement. This work demonstrates that our AAO template-assisted strategy can construct vertically ordered nanostructures with sharp nanoedges, and that these vertically ordered sharp nanoedges can enhance HER catalytic activity.