Efficient hydroxylation of benzene to phenol by H2O2using Ni-doped CuWO4on carbon nitride as a catalyst under solar irradiation and its structure-activity correlation

A series of environmentally benign and highly efficient Z-scheme Ni-doped CuWO(4)nanoparticles on graphitic carbon nitride (g-C3N4) were synthesized. The Ni-CuWO(4)nanoparticles were preparedviathe substitution of Ni(2+)on a wolframite CuWO(4)crystal. The photocatalytic activity of these nanocomposites was investigated for the hydroxylation of benzene to phenol, considering the importance of phenol and carcinogenicity of benzene. An excellent benzene conversion of 98.5%, with 82.7% selectivity and 81.5% yield of phenol, was achieved over 0.2% Ni-CuWO4/g-C(3)N(4)in 15 minutes under sunlight using H(2)O(2)as an oxidant in water, which is higher than those of pristine g-C(3)N(4)and Ni-CuWO4. The high yield of phenol is mainly attributed to the narrow band gap of the semiconductor and enhanced visible light absorption capacity over a specific range of wavelength by the introduction of g-C3N4, which minimized the rapid recombination of photogenerated holes and electrons. The computational study related to this work also implied the high optical property and stability of the photocatalyst.