A Sustainable Approach for the Valorization of Lignocellulosic Biomass in Active Photo- and Electrocatalyst Carbon Dots

The recovery or degradation of organic wastes in the circular economy concept continues to be environmental protection challenges. In this study, we proposed a metal catalyst free production of useful non-doped (CDs) and nitrogen doped carbon dots (N-CDs) nanoparticles, generated from a greener hydrothermal top-down method, using paper scraps solid organic wastes from the pulp and paper industry. Both materials were fully characterized. At the same time, these high-added value materials were used as catalysts for the photocatalytic degradation of pollutants and for generating hydrogen through hydrogen evolution reaction (HER). The morphological study revealed the presence of nanoparticles with a higher carbon content than the raw biomass, from 13 to 51 wt% as assessed by X-ray photoelectron spectroscopy (XPS), ranging in size from 4.4 to 6.8 nm. The ability of these materials to catalyze the photodegradation of 4-nitrophenol has been tentatively investigated. The N-CDs proved to be more active than undoped-CDs to degrade 4-nitrophenol due to the smaller bandgap and more active sites available which will also accept the transferred electrons for H 2 generation or 4-nitrophenol reduction. Graphical abstract