Biomass-Assisted Synthesis of CeO₂ Nanorods for CO₂ Photoreduction under Visible Light

CO2 photoreduction into high-valued fuels is considered as a promising route to alleviate the clash between the environment and energy. Morphology-dependent CeO2 nanocrystallines with special crystal planes and increased amounts of specific surface areas, structural defects, and active sites have recently demonstrated excellent performance in catalysis. In this article, a biomass-assisted synthesis of CeO2 (BC) photocatalyst is successfully synthesized via a simple yet effective hydrothermal-calcining method by using commercial Ce(NO3)3 as a precursor and leaves of Alternanthera philoxeroides (LAP) as a crystal growth modifier. The amount of LAP introduced into the precursor has a significant effect on regulating the growth of the formed CeO2 from nanocubes to nanorods for the resulting BCs. Owing to the emergence of the just right microenvironment for regulating the growth of the CeO2 nanocrystalline, the optimal sample of BC-15 with a morphology of nanorods is found to be the most efficient one as a photocatalyst for CO2 reduction under visible light. As the major product, the CO yield (126.8 μmol g–1 at a reaction time of 6 h) of BC-15 is ∼7.4-fold of the reference CeO2 nanocubes synthesized without LAP in the precursor. In addition, the underlying evolution process of the nanorods and detailed mechanism insight into the boosted CO2 photoreduction performance are investigated by means of a series of experimental characterizations and results. The present work provides a meaningful protocol to utilize the crystal phase engineering strategy to design morphology dependence of photocatalysts and assisted synthesis with renewable biomass materials for solar-to-fuel conversion.