Transparent Porous ZnO|Metal Complex Nanostructured Materials: Application to Electrocatalytic CO2 Reduction

We developed a simple and versatile approach for theelectrochemicalgrowth of hybrid ZnO|molecular catalyst nanostructured layers. Metaloxide|catalyst hybrid nanoporous layers with a sponge-like structureat the nanoscale and multiscale three-dimensional (3D) hierarchicalstructures based on nanoporous zinc oxide (ZnO) layers grown on ZnOnanorods were obtained. The thickness and structure of the hybridnanoporous layers as well as the catalyst concentration can be tuned.This method allows the introduction of water-soluble molecular catalystsbased on porphyrin and/or phthalocyanine derivatives into the ZnOmatrix with a homogeneous distribution of the complex into the material.As an illustrative example, combining hybrid ZnO with a very low concentrationof an encapsulated Co-based molecular catalyst inside the oxide layerresults in a 97% catalytic response toward CO2 reductionto CO with large currents in an organic solvent, highlighting theexcellent electrocatalytic activities of such layers, which combineporosity, electronic conductivity, and synergetic properties fromits components.