Coupling the Surface Plasmon Resonance of WO3–x and Au for Enhancing the Photocatalytic Activity of the Nonoxidative Methane Coupling Reaction

The surface plasmon resonance (SPR) effect of oxygen-deficient WO 3– x has been utilized for photocatalysis in the literature. A unique feature of WO 3– x is that its plasmonic peak can be adjusted to the visible light range, which is close to that of typical plasmonic metals like Au. In this work, we have demonstrated the coupling effect of the SPR of WO 3– x and Au can significantly alter the photocatalytic activity toward the gas phase nonoxidative methane coupling reaction in terms of the C 2 product rate and selectivity. A photocatalyst composed of Au and WO 3– x nanoparticles of comparable size is prepared by the simple Pechini method and thermal reduction in a H 2 containing atmosphere. The SPR of Au can mainly promote C 2 H 6 production, while the SPR of WO 3– x can mainly increase the selectivity to C 2 H 4 . Combining two such strategies can give a composite photocatalyst with a higher C 2 production rate and almost 100% selectivity to C 2 H 4 under visible light. Detailed characterization reveals that the coupling of Au and WO 3– x can effectively prolong the charge lifetime and the charge generation rate, and improves the hydrogen evolution activity, which results in much higher photocatalytic activity.