关键词: 纳米花, 核壳结构, Ru@Pt_0.24Ru, 碱性氢析出反应

Abstract:

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.

Key words: nanoflowers, core-shell structure, Ru@Pt_0.24Ru, alkaline hydrogen evolution reaction