Black magnetic Cu-g-C3N4 nanosheets towards efficient photocatalytic H2 generation and CO2/benzene conversion.

• Cu clusters were embedded into graphitic carbon nitride to obtain black nanosheets. • Enhanced ferromagnetism of the black nanosheets is found for the first time. • The black nanosheets reveal enhanced H 2 , CO, and CH 4 generation in visible light. • High conversion rate and high selectivity to phenol achieved for benzene oxidation. Copper (Cu) clusters are incorporated into graphitic carbon nitride (g-C 3 N 4) via a two-step thermal polymerization process, forming a superior thin black g-C 3 N 4 nanosheets based Cu cluster composite (Cu-g-C 3 N 4) with highly efficient charge transfer characteristic and enhanced photocatalytic activity. The Cu–N bonding is formed through intercalation of copper atoms (using Cu (II) acetylacetonate as Cu source) into dicyandiamide-based supramolecular precursor via mechano-chemical reaction, and the Cu atoms and the N atoms are bonded together in two ways: between one Cu atom and four coordinated N atoms (that comes from adjacent carbon nitride layers) and between one central Cu atom and the three N atoms from identical carbon nitride layer forming an in-plane system. Enhanced ferromagnetism of black Cu-g-C 3 N 4 nanosheets is found for the first time, opening the way to deepen the understanding of the material in novel undiscovered applications and to generate fundamental knowledge of ferromagnetism of Cu incorporated g-C 3 N 4 composite material. This black Cu-g-C 3 N 4 nanosheets composite reveals enhanced visible-light-responsive photocatalytic hydrogen generation (526 μmolg-1h−1) as well as excellent CO (5.0 μmolg-1h−1) and CH 4 generation (2.4 μmolg-1h−1) efficiency. Moreover, outstanding conversion rate (90.4 %) and high selectivity to phenol (99.1 %) are obtained in visible-light-driven benzene oxidation application. [ABSTRACT FROM AUTHOR]