The modern lifestyle is heavily reliant on electromagnetic (EM) radiation, which has a wide range of applications depending on its wavelength [[1], [2], [3]]. Microwaves and radio waves, which have frequencies lower than those in the far-infrared spectrum, are widely employed in broadcasting, information, and communication technologies to transmit signals [4]. Due to the rapid rise in mobile phone usage, the development of the internet of things (IoT), and the growing usage of a number of other electrical and electronic devices, high-frequency electromagnetic waves, also known as microwave and radiofrequency waves, are continuously emitted through a variety of antenna types all around us [5]. Electromagnetic radiation from nearby sources can combine and disrupt the regular functioning of adjacent electronic components. When two signals interact and produce unintentional changes, it is known as electromagnetic interference (EMI) [6]. EM interference (EMI) is the term used to describe this kind of coupling or interference. Electromagnetic interference (EMI) can cause electronic devices to malfunction or perform poorly. The growing reliance of modern civilization on computers, digital electronics, and low-voltage signal circuits has resulted in an increase in EMI-related issues [7]. For example, personal electronic devices must be switched off during takeoff and landing in order to prevent electromagnetic interference (EMI) from impairing the pilot's communication with ground stations or even interfering with the regular operation of the aircraft's instruments. Electromagnetic interference (EMI) can originate from natural phenomena like solar flares, thunder, and electrostatic discharge. It can also arise from nearby electronic devices that create electromagnetic waves as a result of flaw or design. Strong electromagnetic fields produced by MRI machines have the potential to interfere with nearby electrical devices, including medical ones [8]. Strong EM radiation used in broadcasting and telecommunications can be harmful to people's health over time. It can change the blood flow to the brain and can lead to serious illnesses including leukemia and brain tumors [9]. Fig. 1 shows a few potential electromagnetic wave sources as well as some potential interference-affected equipment. Thus, the urgent need to reduce harmful EM pollution and radiation drives the development of high-performance microwave absorption and EMI shielding materials in the GHz range [10,11].

Designed to act as a barrier, EMI shielding keeps away electromagnetic radiation that could otherwise interfere with communications and electronics [12]. Magnetic fields can easily interfere with some electrical equipment because of the very low voltages and currents they use. The two basic ways to protect against EMWs are by absorption and reflection. Since the surrounding region may be harmed by the reflected EMWs, the absorption method is recommended for shielding from a safety standpoint. Therefore, EMI shielding-especially in the military and civil divisions-is one of the finest methods for protecting the environment and the health of living things from the harmful effects of electromagnetic waves [[13], [14]].

Zinc oxide (ZnO) semiconductor nanoparticle, a type of superior multifunctional material, have exceptional physico-chemical characteristics such high chemical stability, high electrochemical coupling coefficient, wide radiation absorbance range, and high light stability [15]. It is one of the most widely used semiconductor metal oxide [[16], [17]]. In fact ZnO exhibits a rare combination of excitonic stability and a high band gap energy of approximately 3.4 eV. It can be considered for light emission applications due to its high excitonic energy of approximately 60 meV [18]. ZnO is an n-type semiconductor whose intrinsic defects, such as oxygen vacancies and interstitial zinc atoms, are primarily responsible for its electrical conductivity. It is possible to increase electrical conductivity by doping with different group III or group VII elements [19]. Because of its strong pyroelectric and piezoelectric properties, ZnO is a good choice for applications including the manufacturing of piezoelectric sensors and mechanical actuators [20]. As a result of its great biocompatibility and antibacterial qualities, ZnO has also found widespread application in biosensing and biomedical applications [21].

Currently, materials based on ZnO provide ideal options for reducing electromagnetic wave pollution because of their superior dielectric loss characteristics [22]. It has been demonstrated that the electromagnetic wave absorption properties may be successfully modified by controlling the grain size, morphology, and microstructure of ZnO semiconductors by adjusting the preparation approach and also constructing creative nanocomposites [23]. Currently, most studies combine ZnO semiconductor with graphene, multi-wall carbon nanotube, metal nanoparticles and its alloys, two-dimensional MXene, spinel ferrite magnetic nanoparticles, polymer systems, textiles, etc. to acquire excellent microwave absorption properties. For example, Gaihua He et al. [24] reported superior electromagnetic wave absorption based on ZnO capped MnO2 nanostructures. In comparison to pure ZnO or MnO2, the compositions improved the electromagnetic wave attenuation performance, improve relative permittivity, and meet impedance matching requirements. A design guide for binary heterogeneous transition metal oxide dielectric-dielectric loss type electromagnetic wave absorption composites with improved microwave absorption performance over a wide frequency range is provided by heterogeneous nanostructures with large specific surface area and rich interfaces. Additionally, ZnO nanowires were used to modify three-dimensional reduced graphene oxide foam by Xin Liu et al. [25] for improved microwave absorption capabilities. Due to optimized impedance matching, increased polarizations, numerous residual oxygen functional groups, and defects of N doped reduced graphene oxide (N-RGO), the composite's electromagnetic wave absorption properties were improved.

This review article describes the recent research progress on ZnO semiconductor nanostructures and its nanocomposites for electromagnetic interference shielding and microwave absorber (Fig. 2). This is the first review of ZnO nanocomposites for microwave absorption and EMI shielding. More attention is paid to innovative nanocomposites such as ZnO-graphene based nanocomposites, ZnO-MXene based nanocomposites, ZnO‑carbon nanotubes-based nanocomposites, ZnO-metal and its alloys-based nanocomposites, ZnO-spinel ferrite-based nanocomposites, ZnO-polymer based nanocomposites, ZnO-textile based nanocomposites and its designs strategies on the electromagnetic properties and electromagnetic wave absorption mechanisms. Finally, future research and development in ZnO based nanocomposites for electromagnetic absorption are discussed.