Investigation of Hydrogen and Oxygen Evolution on Cobalt-Nanoparticles-Supported Graphitic Carbon Nitride
Aušrinė Zabielaitė, Aldona Balčiūnaitė, Daina Upskuviene, Dijana Šimkūnaitė, Ramūnas Levinas, Gediminas Niaura, Jūrate Vaičiūnienė, Vitalija Jasulaitienė, Loreta Tamašauskaitė–Tamašiūnaitė, Eugenijus Norkus
Abstract
This study focuses on fabricating cobalt particles deposited on graphitic carbon nitride (Co/gCN) using annealing, microwave-assisted and hydrothermal syntheses, and their employment in hydrogen and oxygen evolution (HER and OER) reactions. Composition, surface morphology, and structure were examined using inductively coupled plasma optical emission spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The performance of Co-modified gCN composites for the HER and OER were investigated in an alkaline media (1 M KOH). Compared to the metal-free gCN, the modification of gCN with Co enhances the electrocatalytic activity towards the HER and OER. Additionally, thermal annealing of both Co(NO3)2 and melamine at 520 °C for 4 h results in the preparation of an effective bifunctional Co3O4/gCN catalyst for the HER with the lower Eonset of −0.24 V, a small overpotential of −294.1 mV at 10 mA cm−2, and a low Tafel slope of −29.6 mV dec−1 in a 1.0 M KOH solution and for the OER with the onset overpotential of 286.2 mV and overpotential of 422.3 mV to achieve a current density of 10 mA cm−2 with the Tafel slope of 72.8 mV dec−1.