(521bv) Coke-Resistant Single Atom Catalyst for C?H Bond Activation of Methane

The recent push towards sustainable hydrogen that can be produced from natural gas and supported by permanent carbon capture has sparked renewed interest in C–H bond activation of methane. The current catalysts used for this process deactivate easily due to coke formation on the surface of the catalyst. Coke formation is known to be caused by strong binding of CH_x intermediates and a net exothermic reaction pathway. A promising catalyst must be able to activate C−H bonds while being able to resist coke formation. Recently, single Ni atoms have been reported to be deposited on titanium nitride (TiN) plasmonic nanoparticles and that the single Ni atoms favorably deposit on N-vacancy sites on the TiN surface. Supported by computational results, single atom catalyst (SAC) formation has been confirmed through experimental TEM imaging and XPS results. Utilizing ab initio spin-polarized DFT calculations, the present work shows the simulation of intermediate C–H bond transition states and the energy barriers of the SAC nickel deposited on titanium nitride (Ni-TiN). The highest activation energy of the simulated pathway was found to be 1.10 eV. This finding along with weaker binding to adsorbates and a net endothermic pathway shows that Ni-TiN is expected to resist coke formation on its surface and stay active as a catalyst.

Acknowledgments

Acknowledgment is made to the State Legislative Fund, New Mexico for financial support. This work used Stampede2 at TACC through allocation [TGDMR140131] from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by National Science Foundation grants #2138259, #2138286, #2138307, #2137603, and #2138296. This work also utilized resources from the University of Colorado Boulder Research Computing Group, which is supported by the National Science Foundation (awards ACI-1532235 and ACI-1532236), the University of Colorado Boulder, and Colorado.