Unique sandwich structure of Ru@TiO2: salicylic acid micro-etching from K2Ti2O5 and high-performance electrocatalytic hydrogen evolution

An Ru@TiO2 sandwich structure of TiO2|Ru|TiO2 is developed via a novel synthesis method by etching two-dimensional K2Ti2O5 in a salicylic acid solution and further inserting Ru nanodots between anatase TiO2 layers. In this sandwich structure, Ru nanodots are in close contact with anatase TiO2 layers and dispersed more on the edge, which promotes electron transfer and limits the aggregation of Ru nanoparticles. The orientation distribution of the Ru@TiO2 sandwich obtained with processing electron diffraction (PED) indicates that {002} crystal planes are dominant for Ru nanodots, which exhibit high HER activity. Applied to the hydrogen evolution reaction (HER), a 2.54 wt% Ru@TiO2 sandwich not only shows comparable activity to 20 wt% Pt/C but also exhibits higher current densities at low potentials. Meanwhile, the mass and price activities of Ru@TiO2 sandwich are 13 and 50 times, respectively, higher than those of 20 wt% Pt/C. This report provides a novel approach to designing the morphology of hetero-structured catalysts.