Transition metal nitrides (TMNs) have been explored as effective supports for Pt due to their Pt-like electronic properties. However, there is a lack of fundamental understanding regarding the behavior of supporting Pt on different TMNs. Herein two TMNs, Mo2N and TiN, were modified with Pt and their reaction pathways for methanol decomposition were compared using both ultra-high vacuum (UHV) studies over thin films and ambient-pressure batch reactor studies of powder catalysts. Temperature programmed desorption and high-resolution electron energy loss spectroscopy experiments were conducted in UHV chambers with Mo2N and TiN thin films to experimentally reveal C-O and C-H bond scission pathways of methanol. Mo2N was shown to have high selectivity towards C-H scission to form CO as the primary desorption product, while TiN favored C-O scission to form CH4. The addition of 1ML Pt on either TMN surface increased the selectivity towards CO formation while suppressing C-O scission. Density functional theory (DFT) calculations for methanol decomposition revealed that the binding energy of O (BE*O) is significantly reduced on Pt/TMN surfaces compared to TMN surface such that C-O bond scission pathways are suppressed, leading to the observed experimental trends. These results on thin films were extended to powder catalyst studies in a batch reactor. Methanol decomposition on Pt/Mo2N and Pt/TiN powders showed similar trends in C-H and C-O scission selectivity to those of TPD experiments. Both thin film and powder catalyst studies demonstrate that Pt-modification on Mo2N and TiN reduces BE*O and BE*CO leading to enhanced CO selectivity. Mo2N especially shows promise as an active catalyst support due to its inherent Pt-like selectivity observed in both UHV and batch reactor experiments.
