Nickel phyllosilicates functionalized with graphene oxide to boost CO selectivity in CO2 hydrogenation

• Pure m NiSiO 3 catalyst exhibited predominant CH 4 product in CO 2 hydrogenation. • Functionalization of GO could tune CH 4 /CO selectivity in CO 2 hydrogenation. • GO prevent the collapse of layer-structured Ni phyllosilicate during H 2 reduction. • GO adjust the electronic feature of Ni sites from phyllosilicate by H 2 reduction. • Carbonate intermediates are key to CO formation while lowering CH 4 selectivity. Thermal reduction of CO 2 by green H 2 is one of the most effective strategies for CO 2 utilization and preparation of value-added C1 chemicals, which is highly dependent on the catalyst compositions and structures. In this work, hollow mesoporous nickel phyllosilicate ( m NiSiO 3 ) with an average size of 250 nm was used as catalysts for CO 2 hydrogenation after the partial extraction of Ni ions from nickel phyllosilicate. After the reduction treatment by H 2 at 400 o C, the m NiSiO 3 -R 400 showed CO 2 conversion of 22.9% and CH 4 selectivity of 80.9% (300 o C, 0.1 MPa). Interestingly, by functionalization of two-dimensional graphene oxide (GO) onto the nickel phyllosilicate to obtain m NiSiO 3 /GO catalyst, more CO product was obtained and the CO/CH 4 ratio in the products can be easily tuned via the change of GO loading amount. It was found that the functionalization of GO nanosheets on m NiSiO 3 would affect the reduction degree of nickel phyllosilicate and stabilize the structure against collapse during high-temperature reduction. In accordance, the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in different transient states suggested that the formation of bidentate carbonate species may play a vital role in the high selectivity of CO and that CH 3 O* was the key intermediate species over the Ni site for CH 4 formation. Due to the electronic interaction between GO and Ni 0 , it might weaken the interaction between Ni 0 and H 2 , which prevents the direct decomposition of CO* into C* and the further hydrogenation of C* into methane over the Ni 0 sites. This work will provide new references for adjusting the CO/CH 4 selectivity in CO 2 hydrogenation over the Ni-based catalysts.