Effective UV–visible-infrared light-driven photothermocatalytic dry reforming of methane on Ni/Ni-MgO caused by a novel synergetic effect and photoactivation

Abstract

Light-driven photothermocatalytic dry reforming of methane (DRM) is a promising technology which can efficiently convert two greenhouse gases of CO2 and CH4 into fuels and realize effective solar energy storage simultaneously. It is greatly challenging to achieve high fuel production rate with a relatively low light intensity and restrain the coking side-reactions that cause catalyst deactivation. Herein, a novel nanocomposite of Ni nanoparticles (NPs) loaded on Ni-doped MgO (Ni/Ni-MgO) was prepared. Very high production rate (r) of H2 and CO (82.78 mmol min−1 g−1 and 98.05 mmol min−1 g−1) as well as a light-to-fuel efficiency (η, 28.8%) are obtained with concentrated UV–vis IR irradiation at a relatively low light intensity (78.8 kw m−2). Ni/Ni-MgO displays excellent durability due to its very low coking rate of 2.46 × 10−3 gc h−1 g−1catalyst, reduced by 11.6 times as compared to that of a reference sample of Ni NPs loaded on MgO (Ni/MgO). This is attributed to a synergetic effect between Ni NPs and Ni-MgO, in which the active oxygen of Ni-doped MgO participates in the oxidation of carbon species as one of the rate-determining steps of DRM, thus facilitating DRM on Ni NPs and greatly improving coking resistance. A photoactivation is found to greatly reduce activation energy and thus enhances catalytic activity due to the substantial facilitation of carbon oxidation by light irradiation.