Synthesis of Er2Ti2O7 nanocrystals and its electrochemical hydrogen storage behavior

Ultrafine Er2Ti2O7 was synthesized at 700 °C within 2 h by a soft-chemistry route named citric acid sol–gel method (CAM). The obtained Er2Ti2O7 with high dispersibility was square-like and the average size was about 70 nm. The prepared Er2Ti2O7 nanocrystals in 6 M KOH aqueous solutions were investigated as a hydrogen storage material. It was found that the Er2Ti2O7 powders would function as electrochemical hydrogen storage, showed fair electrochemical reversibility, and considerably high charge–discharge capacity. The reversible discharge capacity of the Er2Ti2O7 electrode was found to exceed 320 mAh/g and adsorption capability of hydrogen is up to 1.27% at a current rate of 100 mA/g. In addition, the cycling ability and high rate capability of the Er2Ti2O7 electrode are fairly good with only 4% capacity decay after 25 cycles. Cyclic voltammograms (CVs) were carried out to further examine the electrochemical hydrogen storage mechanism of Er2Ti2O7.