核壳结构Ru@PtRu纳米花电催化剂的制备及碱性氢析出反应性能研究

本文通过分步还原Ru、Pt前驱体,制备了以Ru为核、PtRu合金为壳的Ru@Pt_0.24Ru纳米花电催化剂,其平均直径为16.5±4.0 nm. 利用高分辨电子显微镜、电感耦合等离子体原子发射光谱和X射线光电子能谱等表征了这种电催化剂的结构和组成. 在1 mol·L ^-1 KOH水溶液中,核壳结构Ru@Pt_0.24Ru/C纳米花氢析出反应的过电位为22 mV（@10 mA·cm ^-2）,耐久性测试后过电位增加至30 mV（@10 mA·cm ^-2）,明显优于商业Pt/C电催化剂（初始值：60 mV@10 mA·cm ^-2,耐久性测试后：85 mV@10mA·cm ^-2）. 显著提高的电化学活性可能源于核壳结构Ru@Pt_0.24Ru纳米花的电子效应和几何效应,耐久性的改善可能源于核壳结构Ru@Pt_0.24Ru纳米花结构的稳定性.

Core-Shell Structured Ru@PtRu Nanoflower Electrocatalysts toward Alkaline Hydrogen Evolution Reaction

Water electrolysis for hydrogen production is beneficial for solving the problem of energy crisis and environmental issues. It is necessary to study highly active and cost-effective catalysts toward hydrogen evolution reaction (HER) to reduce the consumption of noble metals. Herein, we report the synthesis of core-shell structured Ru@Pt_0.24Ru nanoflowers electrocatalyst by stepwise reduction of Ru and Pt precursors in the mixture of oleylamine and benzyl alcohol at 160 ^oC. The average diameter of the resultant Ru@Pt_0.24Ru was 16.5±4.0 nm with a bulk atomic ratio between Pt and Ru of 0.24:1 and a surface ratio of 3.3:1 between Pt and Ru. Therefore, we speculate the formation of core-shell structure with Ru as the core and PtRu alloy as the shell. The performance of the electrocatalyst toward alkaline HER was tested in 1.0 mol·L ^-1 KOH aqueous solution. The Ru@Pt_0.24Ru exhibited pronounced alkaline HER activity with a small overpotential of 22 mV at 10 mA·cm ^-2, a low Tafel slope of 43 mV·dec ^-1, and a high mass activity of 5.68 A·mg ^-1_Pt+Ru at an overpotential of 100 mV, all largely surpassing commercial Pt/C (60 mV, 101 mV·dec ^-1, 1.53 A·mg ^-1_Pt). The attained Ru@Pt_0.24Ru also held outstanding long-term cycling stability. After 10,000 potential cycles from 0.1 to -0.1 V (vs. RHE), the overpotential increased to 30 mV at 10 mA·cm ^-2, while increased to 85 mV for Pt/C. The significantly improved electrochemical activity may be derived from the electronic and geometric effects of the electrocatalyst. The improvement of durability may be due to the stability of the flower-like dendritic morphology.