Nanoporous Gold for Energy Applications.

Research activities using nanoporous gold (NPG) were reviewed in the field of energy applications in three categories: fuel cells, supercapacitors, and batteries. First, applications to fuel cells are reviewed with the subsections of proof-of-concept studies, studies on fuel oxidations at anode, and studies on oxygen reduction reactions at cathode. Second, applications to supercapacitors are reviewed from research activities on active materials/NPG composites to demonstrations of all-solid-state flexible supercapacitors using NPG electrodes. Third, research activities using NPG for battery applications are reviewed, mainly about fundamental studies on Li-air and Na-air batteries and some model studies on improving Li ion battery anodes. Although NPG based studies are the main subject of this review, some of meaningful studies using nanoporous metals are also discussed where relevant. Finally, summary and future outlook are given based on the survey on the research activities.