Highly Efficient and Sustainable ZnO/CuO/g-C3N4 Photocatalyst for Wastewater Treatment under Visible Light through Heterojunction Development

Abstract

Dye-containing pollutants are currently a threat to the environment, and it is highly challenging to eliminate these dyes photocatalytically under visible light. Herein, we designed and prepared a ZnO/CuO/g-C3N4 (ZCG) heterostructure nanocomposite by a co-crystallization procedure and applied it to eliminate pollutants from wastewater via a photocatalytic scheme. The structural and morphological features of the composite confirmed the formation of a ZCG nanocomposite. The photocatalytic capability of the ZCG photocatalyst was investigated via the decomposition of methylene blue dye. The outstanding activity level of 97.46% was reached within 50 min. In addition, the proficiency of the ZCG composite was 753%, 392%, 156%, and 130% higher than photolysis, g-C3N4, CuO, and ZnO, respectively. Furthermore, the photodeterioration activity on Congo red was also evaluated and found to be excellent. The enhanced catalytic achievement is attributed to the construction of heterojunctions among the constituent compounds. These properties boost the charge transfer and decrease the recombination rate. Moreover, the reusability of the ZCG product was explored and a negligible photoactivity decline was detected after six successful runs. The outcomes suggest the as-prepared nanocomposite can be applied to remove pollutants, which opens a new door to practical implementation.

Synthesis and characterization of CuO@S-doped g-C3N4 based nanocomposites for binder-free sensor applications

“…This kind of hybrid heterostructured composite is believed to enhance the accumulation of electrons on the conduction band to maintain electron flow and reduce the electron–hole recombination rate which can improve the photocatalytic efficiency of the material. 45 The aggregated particles' dimensions were found to be substantially greater than what were found in the XRD results. The difference between calculated and observed sizes in the HRSEM micrograph is ascribed to the calculated size being that of a single crystallite, whilst the observed size is that of an agglomeration made up of numerous synthesized crystallites.…”

Sustainable Development of ZnO Nanostructure Doping with Water Hyacinth-Derived Activated Carbon for Visible-Light Photocatalysis

“…9d shows the C 1s spectra with peaks at BEs of 285.9 and 289.9 eV for ZnO, corresponding to C−O and C=O groups, respectively [11]. This might be due to residual levels of the starting ammonium bicarbonate.…”

“…Meanwhile, a decrease in O 2− ions and an increase in the compound group were evident in the O 1s spectra of ZnO-AC, suggesting a stronger chemisorption effect of AC on ZnO structures. Figure 9 d shows the C 1s spectra with peaks at BEs of 285.9 and 289.9 eV for ZnO, corresponding to C-O and C=O groups, respectively [ 11 ]. This might be due to residual levels of the starting ammonium bicarbonate.…”

“…The ZnO/Cu-DPA nanocomposite facilitates the conversion of dissolved oxygen (O 2 ) into hydroxyl ( • OH) radicals, suggesting that • OH is the primary active radical involved in the photocatalytic decomposition of MB. The ZnO/CuO/g-C 3 N 4 (ZCG) heterostructure nanocomposite was synthesized via the co-crystallization method and employed in a photocatalytic process to eliminate MB dye from wastewater under visible light [ 11 ]. The MB degradation record was as high as 97.46% within 50 min, exhibiting superior performance to other single photocatalysts such as ZnO, CuO, and g-C 3 N 4 .…”

Effect of the Modification of Catalysts on the Catalytic Performance

“…Preda et al [7] optimized the aqueous ammonia oxidation process to obtain a high ammonia conversion and increase selectivity to gaseous nitrogen-containing products. In reference [8], the authors focused on the preparation of a ZnO/CuO/g-C 3 N 4 (ZCG) nanocomposite through an efficient co-crystallization method, performed a photocatalytic test for the treatment of dye-containing wastewater followed by visible light irradiation and evaluated the material's durability and recycling capability. The outstanding photocatalytic performance was observed due to heterojunction formation among the g-C 3 N 4 , CuO-NPs, and ZnO-NPs compounds, which minimized the photogenerated e − -h + pair recombination and increased the electron flow rate.…”