A one-step, gas-phase hydrogen (H2) surface modification is used to reduce carboxylic groups to phenolic groups on carbon nanotube (CNT) materials. This method efficiently reduces the unselective oxidation sites and enhances the active sites on CNT catalysts used for alkane oxidative dehydrogenation. As a result of the modification, the ethylene selectivity and yield improve by at most 81% and 28% respectively compared to the non-modified catalyst. A clear linear correlation between the functional groups and catalytic activity reveals the effect of specific oxygen species on performance. As the catalyst surface area increases, pretreatments generate more selective active sites instead of over-oxidation sites, providing a guideline for catalyst optimization. We suggest that the gas-phase H2 method is general for reducing carbon catalysts to increase selective oxidation sites for gas phase reactions.
