Ultrathin PdAu Nanowires with High Alloying Degree for the Direct Oxidation of Methane to C1 Oxygenates

The direct oxidation of methane (CH4) into high-valued C1 oxygenates production has garnered increased attention in effectively using vast CH4 and alleviating the global energy crisis. However, due to the high cleavage energy of C-H bond and low polarity of CH4 molecule, it is difficult to activate the first C-H bond. Furthermore, C1 oxygenates are readily inclined to be oxidized to CO2, because their weaker C-H bond comparing with CH4 molecule, resulting in poor selectivity. Herein, we designed ultrathin PdxAuy alloy NWs supported on ZSM-5 (Z-5) to investigate the direct oxidation of CH4 to high value-added oxygenate under mild conditions. By precisely adjusting the molar ratio of Pd/Au and alloying degree, Pd(9)Au(1)NWs/Z-5 showed an excellent yield of 11.57 mmol<middle dot>g(-l)<middle dot>h(-1) and the outstanding selectivity of 95.1% for C1 oxygenates (CH3OH, CH3OOH and HCOOH). The in-situ spectroscopic and mechanism analysis proved that the enhanced catalytic performance of Pd(9)Au(1)NWs/Z-5 was ascribed to the stable one-dimensional nanostructure and the strong synergy effect with high alloying PdAu, which could increase the adsorption capacity of CH4 molecules on Pd atoms to promote the CH4 conversion. This work offers valuable insights into the design concept of high-efficient catalysts and the structure-activity relationship for the direct oxidation of CH4.