Electrochemical Synthesis of Nanostructured Metal-Doped Titanates and Investigation of Their Activity as Oxygen Evolution Photoanodes

Mixed and doped metal oxides are excellent candidates for commercial energy applications such as batteries, supercapacitors, solar cells, and photocatalyts due to their activity, stability, tailorable band edge and bandgaps, and low cost. However, the routes commonly employed in their synthesis present synthetic bottlenecks with reliance on sacrificial materials, the use of high temperatures, long reaction times, and little ability to control morphology, thus compromising their scale-up. Herein, we present the single-pot, electrochemical synthesis of high surface area, doped metal titanate nanostructures, including Na2Ti3O7 (NTO), 25 wt % Sn:NTO, 5 wt % Fe:NTO, and 3 wt % Cu:NTO. The synergistic use of the cathodic corrosion method with suspended droplet alloying (SDA) led to materials with excellent homogeneity, presenting a promising route for the screening, production, and discovery of electroactive materials. As proof of concept of the synthetic control and impact on reactivity, we found that the photoanodic oxygen evolution activity of the nanomaterials was adversely affected by Fe and Sn doping into NTO while Cu doping, at 3 wt %, displayed significant improvement. This work demonstrates the ability of the cathodic corrosion method to obtain compositionally and structurally controlled mixed-metal oxides in a rapid fashion, thus creating new opportunities in the field of materials engineering and the systematic study of compositional gradients on the (photo)­electrochemical performance of metal oxide nanoparticles.