MgO/Ni Nanocomposite and its PVP-modified Derivative for Catalytic CO2 Methanation and Photocatalytic Hydrogen Production

In this study, we show that MgO/Ni nanocomposite (NC) synthesized using Laurus nobilis leaf extract display high catalytic activity toward CO2 methanation and photocatalytic hydrogen production. The polyvinylpyrrolidone (PVP)-modified NC displayed improved dispersion and charge separation, hence enhanced performance. The physicochemical characterization of the NCs revealed thermally stable (<0.5 wt% loss up to 400 °C) single nanocrystals, which may aggregate depending on the preparation technique. Fourier transform infrared spectroscopy coupled with thermogravimetry confirmed the incorporation of 0.45 g PVP per 1 g MgO/Ni. Catalytic performance evaluation showed peak CO2 conversion of 94.56% and 98.74% for MgO/Ni and MgO/Ni@PVP, respectively, at 390°C, with higher selectivity towards CH4 observed for MgO/Ni@PVP across all temperatures. Similarly, MgO/Ni@PVP exhibited higher hydrogen production reaching 1.68 mmol/g.h compared with 1.30 mmol/g.h for MgO/Ni. These results underscore the potential of MgO/Ni@PVP NC as an effective catalyst for renewable energy production and carbon utilization.