2D WS2 and MoS2 functionalized nickel oxide/nanodiamond supported carbon electrocatalysts for oxygen reduction reaction

Abstract

The design of a new electro-catalyst with rich active sites, sufficient surface areas, low cost, and excellent stability for promoting the oxygen reduction reaction (ORR) efficiency is a crucial research topic in the fuel cell's application. Herein, the successful preparation of 2D WS2 and MoS2 functionalized NiO nanoparticles onto the surface of nanodiamond and carbon support is reported. The effect of WS2 and MoS2 doping on nickel oxide/nanodiamond activity supported carbon composites (NiO/ND/C) as electro-catalysts for oxygen reduction reaction in an alkaline medium was evaluated. The combination of activated carbon with sp2 hybridization and nanodiamond with sp2 and sp3 hybridization allows for better materials support conductivity. All prepared electro-catalysts exhibit good electrochemical activity towards ORR. It's noticed that the most efficient electro-catalyst for ORR among all the prepared composites is WS2/NiO/ND/C, which exhibits the highest current density of −7.47 mA·cm−2 at a rotating speed of 2500 rpm and a retention stability of 94.3 % after 100-repetitive cycles. Moreover, the WS2/NiO/ND/C composite forces the ORR reaction through the direct four-electron pathway. This work spotlights the effect between the electronegative oxygen atoms, the electropositive Mo and W atoms, and the synergistic effect between WS2 and carbon support. All this information confirms that the as-reported WS2/NiO/ND/C nanocomposite may be considered a hopeful cathodic electrode for ORR catalysis as an alternative catalyst for platinum-based ones.