Optimization of MoP/r-GO Based Hybrids for Electrochemical Water Splitting

Abstract

Hydrogen (H2) production through water splitting has limited commercial applications due to the unfavorable kinetics of the reaction. Electrocatalysts with a robust structure, high levels of catalytic activity, and a high degree of stability are in high demand but challenging. A catalyst is generally needed for efficient electrocatalytic water-splitting. Long-term stability and high catalytic activity are the main obstacles in developing a catalyst for the hydrogen evolution reaction (HER). Water electrolysis is generally known as a more sustainable and viable technique of H2 production than the stream reforming reaction due to its advantages of using water as a reactant, the absence of greenhouse gas emissions, and exceptional H2 generation efficiency. Implementing lowcost water-splitting devices and electrolyzers could result in marketable H2 fuel. Recently, Molybdenum Phosphide (MoP) has been found as a promising family of earth-abundant electrocatalysts for the HER. It has a wide range of compositions and structures, favorable electronic properties, and excellent electrical conductivity, resulting in low overpotentials at operationally relevant current densities and stability in extremely acidic environments. This study reports the synthesis of MoP/RGO-based hybrids electrocatalysts for HER. The optimized MoP/RGO-based hybrid electrocatalyst exhibited an exceptional HER electrocatalytic performance. An efficient MoP/RGO-based hybrid showed promising results. It exhibited an exceptional HER electrocatalytic performance having an overpotential of 96 mV, at a current density of 10 mA/cm2 , in an alkaline solution with a low Tafel slope of 64 mV/dec. The electrocatalyst also exhibited long-term stability with a minor potential decrease over 24 h. RGO is a promising material with high strength during the high-temperature phosphorization process preventing particle clumping and making the catalyst more conductive, improving the HER performance and durability of an electrocatalyst. Bifunctional MoP/RGO porous structure offered more electrolyte and ions transport permeability. The synergistic effect of reduced graphene oxide (RGO) doping with MoP improves electrocatalytic activity. A high electrocatalyst also exhibited long-term stability with a minor potential decrease over 24 h.