(286g) Electrochemical Stability and Hydrogen Evolution Activity of Bare and Platinum-Modified Tungsten and Niobium Nitrides

Authors: 
Denny, S. R., Columbia University
Tackett, B. M., Columbia University
Chen, J. G., Columbia University
Zhang, Q., Columbia University
Sasaki, K., Brookhaven National Lab
Tian, D., Columbia University
Transition metal nitrides are a class of electrocatalyst supports with similar physical and electronic properties to those of carbides. While transition metal carbides have demonstrated electrocatalytic stability and activity for a variety industrially relevant reactions, these materials often have graphitic overlayers that curtail activity and can impede accurate computational modelling for high surface area catalysts. Nitride analogues are inherently “clean” in that they do not have carbonaceous overlayers, which may further capitalize the application of Density Functional Theory (DFT) calculations of interactions between supported metal and nitride substrates. Demonstrated in this study is the stability behavior of tungsten nitride (WN) and niobium nitride (NbN) thin films over a wide pH region between 1 and 13, from which pseudo-Pourbaix diagrams are made to exhibit surface passivation and oxidation behavior. Furthermore, the hydrogen evolution reaction (HER) is used as a probe reaction. The HER activity of Pt-modified WN and NbN is assessed in both acid and alkaline electrolyte in conjunction with DFT-calculated hydrogen binding energies. This study develops a framework through which WN and NbN can be employed as stable catalyst supports for a range of electrochemical reactions.