Photo-enhanced dry reforming of methane over Pt-Au/P25 composite catalyst by coupling plasmonic effect

Driving the dry reforming of methane (DRM) reaction via integrating the photo and thermal catalysis is a promising strategy to release the greenhouse effect caused by greenhouse gases (CH₄/CO₂). However, existing photo-thermal catalysts have limited response range to light (ultraviolet region), and broadening light response region to reaching high-performance is quite critical for DRM reaction. Here, the Pt-Au/P25 photo-thermal catalyst was proposed. The catalyst showed obvious enhancement of response range that widened to visible light region. The catalytic performance of catalyst was improved by the SPR effect. The structure–activity relationship was determined by XRD, XPS, Raman, UV–vis and PL spectra. Pt-Au/P25 catalytic performance was evaluated in different light irradiation intensity and reaction temperature. It was found that light irradiation greatly increased the catalytic performance of DRM reaction. The formation rate of H₂ was 85.38 mmol·gcat⁻¹·h⁻¹ and 201.92 mmol·gcat⁻¹·h⁻¹ for CO at 500 °C under 4.6 W·cm⁻² light irradiation intensity, which were 3.09 times for H₂ and 2.08 times for CO compared with dark conditions. Moreover, The DRM reaction mechanism was investigated by in situ DRIFTS test. It was found that among the intermediate species (CH_x, HCOO*, H* and so on), HCOO* was critical species for the DRM reaction to proceed. During the photo-thermal DRM reaction process, activation/dissociation of CH₄ and CO₂ and formation of H₂ steps were strengthened due to photoelectric and SPR effect by light irradiation.