## 1 Introduction  
With rapid global population growth, urbanization increasing, illicit misuse of freshwater resources, and continued destruction of the global climate, the increasing demand for clean water is becoming a global concern [1; 2; 3]. Seven billion people, more than 15% of the world's people, are facing a shortage of fresh water resources, which even causes them to not have enough fresh water to sustain normal life and productive work [4; 5]. Water scarcity is exacerbated by the increasing water pollution from releases of waterborne pathogens, inorganic pollutants, organic pollutants, agricultural chemicals, derivatives of human and animal drugs, and endocrine disruptors [6; 7; 8]. Infectious diseases caused by biological contamination such as typhoid fever, dysentery, cholera, and diarrhea are a major cause of death worldwide and continue to replicate at an alarming rate [9]. The extensive use of antibiotics and antibacterial drugs has led to strong drug resistance in viruses and bacteria, which further exacerbates the spread of biological infectious diseases [10]. In addition, the recent epidemics of global security issues such as the COVID-19 virus and monkeypox virus are caused by the spread of viruses that threaten all human beings and have a great impact on human production, life, and health [11; 12; 13; 14]. Similar to bacteria and pathogenic microorganisms, epidemic viruses are always difficult to eradicate due to the abuse of antibiotics and various disadvantages of disinfectants [15; 16]. In view of the above situation, it is crucial to explore more effective solutions and approaches. Recent advancements in semiconductor materials and new nanomaterials have blazed new trails for their applications in the fields of photocatalysis and bacterial inactivation [9]. Nanotechnology provides a variety of promising nanomaterials for the field of photocatalytic antimicrobial. Metal oxides have many advantages such as non-toxic, stable, and efficient biological properties, which make them stand out among many nanomaterials and become a research hotspot in this field. Numerous nanomaterials doped with metal oxides such as ZnO [17], Fe\({}_{2}\)O\({}_{3}\)[18], TiO\({}_{2}\)[19], Ag\({}_{2}\)O [20], CaO [20], MgO [21], and CuO [22] have been applied as efficient antibacterial agents for both Gram-positive (G+) and Gram-negative (G-) bacteria, such as _Escherichia coli_, _Salmonella enteritidis_, _Streptococcus pyogenes_, _Aeromonas hydrophilic_, _Pseudomonas aeruginosa_, _Salmonella typhimurium_, _Fecal intestinal cocci_, etc. [23]. Among the antibacterial agents, ZnO-based nanomaterials are widely recognized as promising antibacterial agents with strong photocatalytic antibacterial activity [24; 25]. Nevertheless, the wide bandgap of ZnO is approximately 3.2-3.3 eV, which affects its light absorption ability, resulting in a response only in the ultraviolet band [26]. Previous studies indicated that defects of nanomaterials in photocatalytic antibacterial processes could be effectively improved after being modified [27]. Strategies, such as loading antibacterial agents, loading oxidized nanomaterials, and adjusting the particle size, material microshape, and concentration of ZnO were employed to enhance the antibacterial properties. While exploring the antibacterial ability improvement, the antibacterial mechanism should also be in-depth investigated. In previous studies, some mechanisms for photocatalytic antimicrobials, such as metal ion release, reactive oxygen species (ROS) generation [28], destruction of cell membranes, internalization of nanoparticles [29], interruption or blockade of transmembrane transport, etc., have been proposed [30; 31]. Overall, the purpose of all antibacterial mechanisms is to disrupt the bacterial cell structure and break it down into harmless substances. However, our understanding of the specific process of substance transformation during the photocatalyst-induced antimicrobial process is still very limited, which requires further exploration.