(254a) Engineering Non-Sintered, Metal-Terminated Tungsten Carbide Nanoparticles for Catalysis

Hunt, S. T. - Presenter, University of Delaware
Nimmanwudipong, T., Massachusetts Institute of Technology
Roman, Y., MIT

Transition metal carbides (TMCs) exhibit catalytic activities similar to platinum group metals (PGMs), yet TMCs are orders of magnitude more abundant and less expensive. However, current TMC synthesis methods lead to sintering, support degradation, and surface impurity deposition, ultimately precluding their wide-scale use as catalysts. We present a method for the production of non-sintered, metal-terminated TMC nanoparticles (NPs) in the 1–4 nm range with tunable size, composition, and crystal phase.  The method has been extended to synthesize both monometallic carbides and nitrides as well as various heterometallic combinations from the Group IV-VI block of early transition metals.

We show that carbon-supported tungsten carbide (WC) and molybdenum tungsten carbide (MoxW1-xC) nanoparticles are highly active and stable electrocatalysts. Specifically, activities ca. 100-fold higher than commercial WC and within an order of magnitude of platinum-based catalysts are achieved for the hydrogen evolution and methanol electrooxidation reactions.  Using density functional theory (DFT) calculations, we attribute the higher activity of MoxW1-xC NPs to modulation of the hydrogen binding energy (HBE) via bulk heteroatom insertion in the WC lattice. This method opens an attractive avenue to replace PGMs in high energy density applications such as fuel cells and electrolyzers.