Photocatalytic conversion of methane into methanol: Performance of silver impregnated WO3

A detailed investigation of photocatalytic conversion of methane into methanol, over Ag+ impregnated WO3, is reported. The intense monochromatic light source, 355 nm laser photons exposure, facilitated the study of complex processes in short span of time. The characterization techniques, XRD and XPS, confirmed that Ag+ ions share surface oxygen with WO3 to give Ag2O, which enhanced the absorption of photons, lifetime of excited states. The study encircled all the processes that occur on the surface of the catalysts as well as in the bulk that included water splitting, methanol formation as a result of methane conversion and degradation of methanol immediately after its formation. The measurement of evolved H2 and O2 in the gaseous phase and methanol in the liquid phase revealed that the methanol, instantly after its formation, competes with water molecules for the photogenerated holes and decomposes. Efforts have been made to correlate all the processes involved and to estimate the plausible mechanism for in-situ methane conversion and methanol degradation.