Micromorphology and Phase Composition Manipulation of Nanoporous Gold with High Methanol Electro-oxidation Catalytic Activity through Adding a Magnetic Field in the Dealloying Process

摘要

By dealloying a rapidly solidified (RS) Al2Au alloy, nanoporous gold (np-Au) samples with a threedimensional (3D) interpenetrating ligament-channel structure are fabricated in 0, 0.02, and 0.2 T magnetic fields. Adding magnetic field leads to intermediate AIAu phase formation, decreases the dealloying rate, and triggers the formation of fine nanocrystals and amorphous phase in the np-Au ligaments. The np-Au samples dealloyed in 0, 0.02, and 0.2 T for 24 h (DAO, DA1, and DA2) appear in maze-like, honeycomb-like, and soda cracker-like micromorphologies, respectively. The DA1 sample possesses the smallest lattice constant a(0), and highest preferred orientation factor F-(111) of the (111) face. The parameters like surface coverage of the redox species Gamma*, charge-transfer rate constant k(s), exchange current density j(0), corrosion potential E-corr, and charge transfer resistance R-ct indicate that the methanol electro-oxidation activity samples is in this order: DA1 DA2 DAO, which can be ascribed to crystallographic, thermodynamic, and defective reasons. This work supplies a new method to enhance the methanol catalytic activity of np-Au.