Facile fabrication of a novel nanoporous Au/AgO composite for electrochemical double-layer capacitor

In this work, a novel nanoporous gold/silver oxide (NP Au/AgO) composite (NPAAC) was fabricated by a simple two-step partial dealloying-stripping process. Microstructural and electrochemical characterizations suggested that the NPAAC has a bicontinuous, interpenetrating nanoporous structure with ultrafine ligament-channel sizes down to ∼10 nm, and it delivered a rectangle cyclic voltammetry (CV) curve with a wide electrochemical double-layer region from -0.3 to 0.7 V (vs. Ag/AgCl in sulfuric acid) and a specific capacitance of ∼80 F g^-1. Moreover, the NPAAC revealed a superior cyclic performance as compared to metal-based pseudocapacitors, with stable charge-discharge cycling at ∼77 F g^-1 for more than ten thousand times with no detectable degradation. This work demonstrates that the new systems of nanoporous noble metal/metal-oxide composites could be similarly fabricated by this approach and developed as potential double-layer capacitors with comparable cyclic performance to carbon-based supercapacitors.