1. Introduction
At present, the form of global environmental pollution is severe, and environmental problems pose a major threat to mankind [1-3]. Solar energy is a renewable energy source, but its development is greatly limited due to its low utilization rate and severe environmental pollution. Therefore, how to efficiently use solar energy and effectively manage environmental pollution has become an important issue that human society is facing and urgently needs to solve [4-5]. Semiconductor photocatalytic technology provides a new choice for solving the problem of global environmental pollution [6-7]. Since TiO2 was first used as a photoanode to decompose water under UV irradiation in the 1970s [8], the application of nano-TiO2 semiconductor photocatalytic oxidation technology in the field of environmental pollution control has opened a new chapter. The so-called photocatalytic reaction is a process in which the reaction system containing the catalyst excites reaction molecules under light irradiation or excites the catalyst to form complexes with reaction molecules to transform light power into chemical power and improve reaction efficiency [9]. However, due to the large band gap of TiO2, its photocatalytic reaction can only be carried out under ultraviolet light, and the utilization rate of sunlight is low. In response to this practical issue, people have been committed to developing efficient visible-light catalytic materials. In response to this issue, this project aims to further optimize the photocatalytic performance of TiO2 based on preliminary work. At present, the main research methods include precious metal deposition, co-doping, metal ion doping, etc. At the same time, they are also researching new photocatalytic materials.
Ag3PO4 has high photocatalytic efficiency and can degrade organic pollutants under the conditions of sunlight and visible light. However, Ag3PO4 is easily reduced to elemental Ag under visible light irradiation [10], which restricts its practical use. In order to better utilize sunlight as a clean energy source, people have conducted extensive research and development. Therefore, people organically combine these two types of semiconductors with different band structures, hoping to accelerate the separation of photogenerated charge carriers and enhance their photocatalytic activity.
Zhang et al. prepared an Ag3PO4/SnO2 composite photocatalyst by combining Ag3PO4 and SnO2, which not only showed strong photocatalytic performance but also enhanced the stability of the composite [11]. In the experiment of degrading methyl orange wastewater, the reusability and stability of Ag3PO4/TiO2 composite photocatalytic material prepared by Li et al. were significantly improved compared with Ag3PO4 and TiO2 [12]. Liu et al. synthesized Bi2GeO5/Ag3PO4nanocomposites by a two-step method and formed Z-type heterojunctions through a subsequent photocatalytic process, which significantly improved their photocatalytic activity and stability [13].
In this paper, ZnCo2O4 nanoparticles were prepared by microwave assisted method and then deposited on Ag3PO4 surface by precipitation method to form ZnCo2O4/Ag3PO4composite catalyst. The structure of the composite was characterized, and its degradation performance in methyl orange wastewater was studied under visible light. Results indicate that ZnCo2O4 can availably improve the stability and photocatalytic degradation properties of Ag3PO4.