In Figure 5a, the photocatalytic degradation of 0.1 ZnCo₂O₄/Ag₃PO₄was analyzed using UV-vis full wave scanning of methyl orange molecules. The results showed that the characteristic peak intensity of methyl orange molecules decreased with the prolongation of reaction time near 464nm, and after 30 minutes, its peak intensity approached 0, indicating that methyl orange had been completely degraded. Fig. 5b shows the photocatalytic degradation of MO by different catalysts Ag₃PO₄, ZnCo₂O₄, 0.1 ZnCo₂O₄/Ag₃PO₄, 0.2 ZnCo₂O₄/Ag₃PO₄, and 0.3 ZnCo₂O₄/Ag₃PO₄. The results showed that the photocatalytic effect of pure ZnCo₂O₄ was the worst, and the photocatalytic degradation rate was only 5% within 30 min. While Ag₃PO₄, 0.2 ZnCo₂O₄/Ag₃PO₄, and 0.3 ZnCo₂O₄/Ag₃PO₄showed 56%, 69%, and 65% photocatalytic degradation at 30 min, respectively. The results showed that the 0.1ZnCo2O4/Ag3PO4 catalyst had the best photocatalytic degradation effect on methyl orange, and after 30 minutes, the degradation rate of methyl orange could reach 94%. This study found that ZnCo₂O₄ can effectively improve the photocatalytic degradation performance of Ag₃PO₄. Fig. 5c shows that the reaction of ZnCo₂O₄/Ag₃PO₄photocatalytic degradation of methyl orange follows the pseudo first-order reaction kinetic model. As shown in Table 3, calculate the k-value of each sample after linearly fitting the curve, and the reaction rate constants of Ag₃PO₄, ZnCo₂O₄, 0.1 ZnCo₂O₄/Ag₃PO₄, 0.2 ZnCo₂O₄/Ag₃PO₄, and 0.3 ZnCo₂O₄/Ag₃PO₄were 0.01793min^-1, 0.00102min^-1, 0.05301min^-1, 0.0229min^-1 and 0.0206min^-1, respectively. The maximum reaction rate constant of 0.1 ZnCo₂O₄/Ag₃PO₄is 0.05301min^-1, which is 3 times that of Ag₃PO₄ and 52 times that of ZnCo₂O₄. These results indicate that the combination of Ag₃PO₄ and ZnCo₂O₄ has a synergistic effect, which can improve its photocatalytic performance. Figure 5d shows the test of stability consequences of Ag₃PO₄ and 0.1ZnCo₂O₄/Ag₃PO₄recycled three times. From the figure, it can be seen that after three rounds of recycling, the degradation rate of MO by Ag₃PO₄ is only 21.8%, while the degradation rate of Mo by 0.1 ZnCo₂O₄/Ag₃PO₄is 84.4%, which indicates that the use of Ag₃PO₄ and ZnCo₂O₄ for compounding can improve the stability of the photocatalyst.

Figure6Trapping experiments of active species during photocatalysis reaction.

Fig. 6 shows the effect of different capture factors on the reaction rate of 0.1 ZnCo₂O₄/Ag₃PO₄photocatalytic degradation of MO. From the figure, it can be seen that the addition of IPA has little influence on the photocatalytic degradation of MO. It can be seen that in the photocatalytic degradation of MO by 0.1 ZnCo₂O₄/Ag₃PO₄, holes (h⁺) and superoxide ions (O-2· ) play the most important roles in the photocatalytic degradation, and hydroxyl radicals (OH·) play a partial role in the degradation.