Leaf-templated synthesis of 3D hierarchical porous cobalt oxide nanostructure as direct electrochemical biosensing interface with enhanced electrocatalysis

A novel three-dimensional (3D) hierarchical porous cobalt oxide (Co₃O₄) architecture was first synthesized through a simple, cost-effective and environmentally friendly leaf-templated strategy. The Co₃O₄ nanoparticles (30-100nm) with irregular shapes were interconnected with each other to form a 3D multilayer porous network structure, which provided high specific surface area and numerous electrocatalytic active sites. Subsequently, Co₃O₄ was successfully utilized as direct electrochemical sensing interface for non-enzymatic detection of H₂O₂ and glucose. By using chronoamperometry, the current response of the sensor at +0.31V was linear with H₂O₂ concentration within 0.4-200μM with a low limit of detection (LOD) of 0.24μM (S/N=3) and a high sensitivity of 389.7μAmM^-1cm^-2. Two linear ranges of 1-300μM (with LOD of 0.1μM and sensitivity of 471.5μAmM^-1cm^-2) and 4-12.5mM were found at +0.59V for glucose. In addition, the as-prepared sensor showed excellent stability and anti-interference performance for possible interferents such as ascorbic acid, uric acid, dopamine, acetaminophen and especially 0.15M chloride ions. Similarly, other various metal oxide nanostructures may be also prepared using this similar strategy for possible applications in catalysis, electrochemical sensors, and fuel cells.