Investigating Ruthenium Nanoparticles Anchored on Functional Porous Carbon Nanospheres for the Oxygen Evolution Reaction

Abstract Ruthenium metal nanoparticles are among the most active catalysts for the oxygen evolution reaction (OER) but suffer from poor stability due to Ru dissolution. Anchoring Ru nanoparticles onto functional porous carbon supports is therefore being explored to enhance stability while retaining high catalytic activity. A Ru-based electrocatalyst consisting of Ru nanoparticles decorated on nitrogen-doped functional mesoporous carbon spheres was synthesized via a one-pot nanoemulsion micelle-assembly method followed by pyrolysis. The nitrogen-doped functional porous carbon spheres facilitate coordination, as evidenced by X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy mapping. Additionally, defects in the carbon matrix accelerate OER kinetics. Electrochemistry-mass spectrometry (EC-MS) measurements on the annealed sample at 1000 °C (Ru/C@1000) reveal the onset of oxygen evolution at 1.4 V vs. RHE. EC-MS reveals the onset of CO2 evolution at potentials above 1.2 V vs. RHE; however, the faradaic efficiency for oxygen evolution approaches unity above 1.4 V vs. RHE, indicating that the anodic current is predominantly due to OER. However, limited catalytic stability under prolonged testing may be attributed to carbon support instability against oxidation and partial oxidation/dissolution of Ru nanoparticles. This study evaluates the effectiveness of anchoring Ru nanoparticles on carbon supports and provides insights for developing stable, efficient Ru/C-based OER electrocatalysts.