Light-promoted dual coking-elimination effects enable highly efficient photothermocatalytic dry reforming of methane on Ni/CeO2–Al2O3

Abstract

Photothermal catalytic dry reforming of methane (DRM) provides an eco-friendly method to convert greenhouse gases (CH₄ and CO₂) into syngas. However, this process requires intense light irradiation and suffers from rapid catalyst deactivation due to carbon deposition. Herein, under a relatively mild light intensity (78.4 kW m⁻²), Ni/CeO₂–Al₂O₃ shows outstanding catalytic activity, generating H₂ and CO at rates of 94.61 and 103.98 mmol min⁻¹ g⁻¹ respectively, with a remarkable light-to-fuel efficiency of 33.5%. Remarkably, compared to Ni/Al₂O₃, Ni/CeO₂–Al₂O₃ exhibits superior photothermal catalytic durability for 50 h, with its carbon deposition rate reduced by a factor of 13.4. The superior photothermal catalytic activity stems from the fact that reactive oxygen species from CeO₂ and carbonate species generated at the CeO₂–Al₂O₃ interface promote the oxidation of carbon species (rate-determining step of DRM), which significantly prevents the carbon species from polymerizing into coke and improves the catalytic activity. Furthermore, it is found that light not only accelerates the oxidation of carbon species and the reaction between carbon species and carbonate species at the interface, but also activates the Ni–O–Ce bonds, which greatly enhances the catalytic performance of Ni/CeO₂–Al₂O₃.