NiSe-Ni3Se2/multiwalled carbon nanotube composites as efficient electrocatalysts for the oxygen evolution reaction in alkaline media
Oyetade, Oluwaseun A.
Kriek, Roelof J.
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The development of effective electrocatalysts for the oxygen evolution reaction (OER) is of great importance to combat energy-related concerns in the environment. Herein, we report a one-step solvothermal method employed for the fabrication of nickel selenide hybrids (NiSe-Ni3Se2) and a series of nickel selenide hybrid/multiwalled carbon nanotube composites (NiSe-Ni3Se2/MWCNT) as electrocatalysts for the OER in alkaline media. The catalytic activities of these electrocatalysts were investigated via several electrochemical characterization techniques, such as linear sweep voltammetry, chronoamperometric studies at constant potential, electrochemical surface area determination, and Tafel slope calculation, under alkaline conditions. Morphological observations demonstrated the agglomeration of non-uniform NiSe-Ni3Se2 microspheres around carbon nanotubes (CNTs), demonstrating the successful synthesis of NiSe-Ni3Se2/MWCNT nanocomposites. Among the tested electrocatalysts, the 20% NiSe-Ni3Se2/MWCNT nanocomposite demonstrated the highest activity, exhibiting an overpotential of 325 mV to achieve a current density of 10 mA.cm−2 in 0.1 mol.dm−3 KOH solution. The NiSe-Ni3Se2/MWCNT nanocomposites showed improved activity toward the OER compared to bare NiSe-Ni3Se2 hybrids and MWCNTs, exhibiting an overpotential of 528, 392, and 434 mV for 10%, 30%, and 50% NiSe-Ni3Se2/MWCNT nanocomposites, respectively. These results compare favorably to the overpotential of noble electrocatalysts, such as RuO2 and IrO2. Our results imply that the addition of MWCNTs increased the activity of NiSe-Ni3Se2 hybrids due to an increased number of catalytic sites, dispersion of NiSe-Ni3Se2 hybrid nanoparticles, and electronic conductivity of the nanocomposites. These nanocomposites also demonstrated better long-term stability compared to NiSe-Ni3Se2 hybrids and MWCNTs. Hence, NiSe-Ni3Se2/MWCNT nanocomposites possess the potential as effective electrocatalysts for the OER in alkaline media