ZnS/MMT nanocomposites: The effect of ZnS loading in MMT on the photocatalytic reduction of carbon dioxide

•ZnS/MMT nanocomposites with 2–4.2 wt.% of ZnS were examined in CO2 photoreduction.•Effect of ZnS loading in MMT on the degree of its aggregation was revealed.•Measurements of ZnS nanoparticles work function were very valuable.•Effect of the ZnS loading in MMT on the energy of electrons and holes was evaluated.•Energy of electrons is the crucial parameter in CO2 photocatalytic reduction.

Different weight loadings (2–4.2 wt.%) of ZnS nanoparticles stabilized by cetyltrimethylammonium bromide (CTAB) were deposited on montmorillonite (MMT) in order to investigate the performance of ZnS/MMT nanocomposites in the CO2 photocatalytic reduction. Physicochemical properties of prepared nanocomposites were comprehensively characterized by using nitrogen physisorption, XRD, TEM, DR UV–vis spectroscopy and contact potential difference measurements. The main reaction products in a gas phase were hydrogen and methane. According to the blank test the pristine montmorillonite did not possess any photocatalytic performance. The order in photocatalytic performance of individual ZnS/MMT nanocomposites in CO2 reduction depending on the ZnS loading was following: 3.1 wt.% ZnS > 4.2 wt.% ZnS > 2.0 wt.% ZnS. This trend was explained based on UV–vis, TEM and contact potential difference measurements as follows. The increasing loading of ZnS nanoparticles affects the degree of ZnS nanoparticles agglomeration on MMT and this agglomeration finally influences the properties/behavior within electronic structure of ZnS, correlating with the photocatalytic performance of ZnS/MMT nanocomposites in the CO2 reduction.

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