Mesoporous Cobalt Tungsten Oxide Heterostructured Nanotoroids for Gas Sensing

Abstract Mesoporous semiconducting nanotoroids of cobalt and tungsten oxides (CoO/Co 3 O 4 /WO 3 ) are made by a hydrothermal reaction of binary metal ionic precursors with aminocaproic acid. The toroidal organization of the primary nanoparticles into the cobalt tungsten oxide nanorings presents a straightforward, interesting approach for amino acid–induced self‐aggregation of hierarchical metal‐based nanostructures. The semiconducting properties of the as‐prepared nanotoroids are exploited in gas‐sensing experiments with three analytes (CO, H 2 , NH 3 ) to demonstrate the toroids as promising gas sensor components. Toroidal geometry, porosity, and semiconductor p–n heterojunction make the new mesoporous Co‐W oxide nanomaterials attractive as novel functional supports for host–guest chemistry, electrocatalysis, and electrochromism.