Unique sandwich structure of Ru@TiO 2 : salicylic acid micro-etching from K 2 Ti 2 O 5 and high-performance electrocatalytic hydrogen evolution

An Ru@TiO 2 sandwich structure of TiO 2 |Ru|TiO 2 is developed via a novel synthesis method by etching two-dimensional K 2 Ti 2 O 5 in a salicylic acid solution and further inserting Ru nanodots between anatase TiO 2 layers. In this sandwich structure, Ru nanodots are in close contact with anatase TiO 2 layers and dispersed more on the edge, which promotes electron transfer and limits the aggregation of Ru nanoparticles. The orientation distribution of the Ru@TiO 2 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@TiO 2 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@TiO 2 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.