Inexpensive and recyclable catalysts, waste regeneration, that utilize safe and available solvents are important factors in laboratory and industrial applications. On the other hand, biochar nanoparticles are new precursors for the solid phase of carbon materials with novel characteristics, which exists synthetically or naturally. Therefore in this work, biochar nanoparticles were prepared from the pyrolysis of biomass resulting from chicken manure. Therefore, it is a suitable method for biomass waste recycling. Then, the surface of biochar nanoparticles was modified by (3-aminoopropyl)trimethoxysilane in n-hexane for 24 h at 60 °C, which the modified biochar nanoparticles were named nPr-NH2@biochar. Next, the modified biochar nanoparticles were functionalized by di(pyridin-2-yl)methanone (DPMI) in ethanol at 80 °C for 24 h, and the functionalized biochar nanoparticles were named as DPMI@biochar. Finally, a new copper Schiff-base complex of di(pyridin-2-yl)methanimine (DPMI) was immobilized on the surface of functionalized biochar nanoparticles (Cu-DPMI@biochar). This biochar-based catalyst nanostructure (Cu-DPMI@biochar) was used as a practical and reusable catalyst in the homoselective synthesis of 5-substituted-1H-tetrazole compounds by [3 + 2] cycloaddition reaction of sodium azide and nitrile derivatives. This catalyst was characterized by scanning electron microscopy (SEM), wavelength-dispersive X-ray spectroscopy (WDX), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy (FTIR), and atomic absorption spectroscopy (AAS) techniques. Cu-DPMI@biochar can be recovered and reused several times.
