pH universal Ru@N-doped carbon catalyst for efficient and fast hydrogen evolution

Abstract

The development of efficient and cost-effective electrocatalysts for the hydrogen evolution reaction (HER) is of intense interest because H₂ is one of the most promising renewable energy sources. Herein, we report a highly efficient and stable HER electrocatalyst composed of ruthenium nanoparticles embedded in nitrogen-doped carbon (NC), which is synthesized via a simple thermolysis process using a ruthenium complex as metal precusor and using ethylenediaminetetraacetic acid tetrasodium (Na₄EDTA) salt as ligand and carbon source. It is found that the amount of Na₄EDTA employed plays an important role in achieving sutiable and uniform Ru nanoparticles. The resulting Ru@NC(1 : 5) was found to exhibit excellent HER activity and robust stability in alkaline media (1.0 M KOH) with a low overpotential at 10 mA cm⁻² (29 mV), small Tafel slope (27 mV per decade) and a high turnover frequency (TOF) of 0.96 s⁻¹ at an overpotential of 50 mV, which are comparable to the state-of-the-art commercial Pt/C catalyst. Based on the characterization of the samples and the electrochemical measurements, this high performance of Ru@NC(1 : 5) is ascribed to its smallest particle size (ca. 2.1 nm diameter), large active site density and the high electrochemical conductivity by the N-doped carbon support. In addition, Ru@NC(1 : 5) also works well in acidic media (0.5 M H₂SO₄) indicating it is a pH-universal catalyst.