Highly Porous Molybdenum and Tungsten Carbides for Hydrogen Evolution Reaction Synthesized from a Sacrificial Leaching

Tuesday, 30 May 2017
Grand Ballroom (Hilton New Orleans Riverside)
M. Kim, D. Song, S. Oh, and E. Cho (Korea Advanced Institute of Science and Technology)
Hydrogen has been considered as one of the most promising energy source for future due to its high-energy density and no air pollutant emission. Water electrolysis into hydrogen and oxygen is an environmentally friendly method to produce hydrogen. Water electrolysis reaction is divided into two half reactions; hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). High overpotential of both HER and OER is the most significant problems to hamper reaction rate and overall efficiency of water electrolysis, which leads to increase in hydrogen production cost. Therefore, exploring active catalysts for HER and OER is one of the major issues in water electrolysis. Platinum (Pt) has been conventionally used as an efficient catalyst for HER. But, its high cost and scarceness is not suitable for a large-scale application of water electrolysis. As for the HER, the electrocatalytic activities of carbide materials, such as molybdenum carbide (Mo2C), and tungsten carbide (WC), have been remarkable among non-precious metal based catalysts. But, it is very difficult to synthesize nanostructured carbides, which is regarded as a main obstacle for increase in HER activity of such carbide based catalyts.

Herein, we report highly porous Mo2C and WC catalysts synthesized from a sacrificial leaching for hydrogen evolution reaction. We firstly synthesized Mo2C and WC composites with cobalt nanoparticles (Co-Mo2C and Co-WC) using graphitic carbon nitride (g-C3N4) as a carbon source, and then leached Co nanoparticles in 0.5 M sulfuric acid (H2SO4) solution. Through this sacrificial leaching method, we could successfully synthesize highly porous Mo2C and WC nanoparticles. Highly porous Mo2C and WC catalysts exhibited much enhanced HER activities in hydrogen saturated 0.5 M H2SO4 solution in comparison to Mo2C and WC nanoparticles synthesized from conventional carburizing method.

Fig. HER activities of highly porous and conventional Mo2C nanoparticles.