Deposition and in-situ formation of nanostructured Mo2C nanoparticles on graphene nanowalls support for efficient electrocatalytic hydrogen evolution

To accelerate the transition to a green economy based on hydrogen, more efficient and cost-effective electrocatalysts should be adapted. Among them, transition metal carbides, particularly Mo2C, have gained significant attention within the scientific community due to their abundance and potential for high performance in the hydrogen evolution reaction (HER). This study introduces a bottom-up approach involving chemical vapor deposition, impregnation in solvent containing the Mo precursor and thermal annealing processes to carburize the Mo nanostructures anchored on vertical graphene nanowalls supports (GNWs). The role of GNWs is highlighted in the above processes. First, they provide abundant defective sites on their edges, which facilitate the binding of the metal compound molecules. Second, they provide C species during the annealing process which migrate and react with the transition metal to carburize it. Thus, they act as both C precursor and support system. Electrochemical characterization shows that the hybrids can be very efficient electrocatalysts towards hydrogen evolution reaction in acid electrolyte. When used as a cathode in a cell, it requires only -141 mV to generate 10 mA/cm2 and shows excellent stability after hours of operation, making them highly promising for practical applications. This study paves the way for the design of hybrid nanostructures, utilizing nanocatalyst deposition on three-dimensional graphene supports. Such advancements hold great potential for driving the development of sustainable and efficient hydrogen production systems.