Development of stable La0.9Ce0.1NiO3 perovskite catalyst for enhanced photothermochemical dry reforming of methane

Solar-driven photothermochemical dry reforming of methane (PTC-DRM) is a promising technique to produce syngas using greenhouse gases (CO2 and CH4). In this work, Ce-substituted LaNiO3, i.e., La1−xCexNiO3 perovskite catalysts were synthesized for PTC-DRM reaction under concentrated sunlight. At 700 °C under 30 suns light irradiation, the CO and H2 production rates were at 616 and 620 mmol g−1 h−1, respectively, over the La0.9Ce0.1NiO3 catalyst, notably higher than those obtained in dark at the same reaction temperature and higher than those over LaNiO3 under the same light irradiation condition. The CO2 and CH4 conversion by the La0.9Ce0.1NiO3 catalyst are among the top-performing catalysts reported in the literature. The Ce substitution of La at a small fraction (x = 0.1) was found to benefit Ni active sites distribution and retention of the perovskite structure, which led to mitigation of both Ni sintering and carbon formation, thus promoting light absorption and PTC-DRM activities. A higher fraction of Ce substitution (x ≥ 0.5), however, did not show any beneficial effects. By conducting in situ DRIFTS at PTC-DRM reaction conditions and control experiment using 495 nm long-pass filter, light irradiation was found to induce photocatalytic activities on La0.9Ce0.1NiO3 and enhance CO2 adsorption and formation of active lanthanum oxycarbonates intermediates (La2O2CO3), possibly due to the generation of oxygen vacancies and electron-hole pairs. This work reports a new catalyst design and mechanistic studies for PTC-DRM reaction, and the findings are of importance for the application low-carbon fuel generation from sunlight.