Direct methane activation by atomically thin platinum nanolayers on two-dimensional metal carbides

Abstract

Efficient and direct conversion of methane to value-added products has been a long-term challenge in shale gas applications. Here, we show that atomically thin nanolayers of Pt with a single or double atomic layer thickness, supported on a two-dimensional molybdenum titanium carbide (MXene), catalyse non-oxidative coupling of methane to ethane/ethylene (C2). Kinetic and theoretical studies, combined with in-situ spectroscopic and microscopic characterizations, demonstrate that Pt nanolayers anchored at the hexagonal close-packed sites of the MXene support can activate the first C–H bond of methane to form methyl radicals that favour desorption over further dehydrogenation and thus suppress coke deposition. At 750 °C and 7% methane conversion, the catalyst runs for 72 hours of continuous operation without deactivation and exhibits >98% selectivity towards C2 products, with a turnover frequency of 0.2–0.6 s−1. Our findings provide insights into the design of highly active and stable catalysts for methane activation and create a platform for developing atomically thin supported metal catalysts. The challenge in non-oxidative coupling of methane lies in the activation of the first C–H bond while avoiding further dehydrogenations, which lead to the formation of coke. Here, atomically thin platinum nanolayers on two-dimensional molybdenum titanium carbides are reported as a superior catalyst for this reaction owing to reduced coke formation.