Single and mixed phases of Co₃O₄, NiO, and CuO nanocomposites were synthesized and investigated as photocatalysts under visible light for degradation of Congo Red dye. Selected parameters were monitored regarding their impacts on photocatalysis, including band gap, crystallite size, specific surface area, zeta potential, composition, and adsorption parameters such as adsorption capacity, equilibrium constant, rate, and thermodynamic quantities. The dominant adsorption mode was chemisorption. Adsorption capacity varied inversely with zeta potential due to repulsion between dye molecule and nanocomposites surface. As the metal content was varied, photocatalytic activity (PCA) depended strongly on type/number of oxides, on charge carrier separation, and adsorption capacity. Specific surface area was less influential to PCA. PCA had little or no dependence on crystallite size, surface charge, adsorption kinetics, equilibrium constant, and thermodynamic parameters. Variation of the band gap did not affect visible-light PCA since all nanocomposites (except NiO) exhibited band gaps in the near infrared.

Co ₃ O _4的单相和混合相合成了NiO和CuO纳米复合材料，并在可见光下研究了其作为光催化降解刚果红染料的催化剂。监测所选参数对它们对光催化的影响，包括带隙，微晶尺寸，比表面积，ζ电势，组成和吸附参数，例如吸附容量，平衡常数，速率和热力学量。主要的吸附方式是化学吸附。由于染料分子和纳米复合材料表面之间的排斥，吸附能力与ζ电势成反比。随着金属含量的变化，光催化活性（PCA）很大程度上取决于氧化物的类型/数量，电荷载流子分离和吸附能力。比表面积对PCA的影响较小。PCA对微晶尺寸几乎没有依赖性，表面电荷，吸附动力学，平衡常数和热力学参数。带隙的变化不会影响可见光PCA，因为所有纳米复合材料（NiO除外）在近红外波段都显示出带隙。