The increasing scarcity of fossil fuels has highlighted the need for alternative energy sources [
1,
2,
3]. Fuel cells are regarded as a promising technology that can be utilized to address this issue. They are widely used in the context of carbon neutralization and carbon peaking. Fuel cells can also work well with other clean energy sources such as methanol. Depending on the electrolyte's type, the fuel cell can be categorized into different types such as proton exchange membrane fuel cells, also known as PEMFCs, solid oxide fuel cells (SOFCs), Alkali fuel cells (AFCs), molten carbonate fuel cells (MCFCs) fuel cells [
4,
5,
6,
7]. The PEMFC is one of the most widely used energy techniques in the world due to its high energy conversion efficiency and lack of pollution [
8,
9]. Direct methanol fuel cell (DMFC) is a promising technology that is expected to revolutionize the way we produce and use electricity [
4,
8]. DMFCs have attracted widespread attention due to their unique attributes, such as their low emission, easy liquid fuel storage, and high energy density [
10,
11]. DMFCs are based on liquid-fuel technology and utilize direct methanol as their fuel for electricity generation [
12]. They are market leaders in the field and are commonly utilized in mobile and off-grid power applications [
13,
14]. Polymer membranes are the main components of direct methanol fuel cells [
15,
16,
17]. DMFCs must be designed to provide high-ion exchange capacity and low-water uptake. They should also have good proton conductivity and a long-life span [
18,
19]. The high proton conductivity of PEM ensures that it can conduct protons efficiently from the anode to the cathode. Its robust fuel barrier helps prevent degradation or even the termination of fuel cell performance [
7]. Its good mechanical properties ensure that it operates in both wet and dry environments. Today's membranes are made from perflurosulphonic acids, which are commonly referred to as Nafion. Unfortunately, Nafion has drawbacks such as high methanol permeability and high cost which also contribute to its application in the fuel cell [
19,
20]. Natural and low-cost abundant chitosan-based polymers can be utilized as an alternative in fuel cells. However, due to their high hydrophilic nature and low proton conductivity, they are not ideal for DMFC applications [
4]. The biopolymer Chitosan is made from chitin, which is found in the shells of insects and crustaceans. With the help of hygroscopic oxide fillers such as silica (SiO
2), Titanium dioxide (TiO
2), and Zirconium Oxide (ZrO
2), they can achieve good membrane properties such as high proton conductivity, low water uptake, high membrane selectivity, and methanol permeability [
21,
22]. Several studies have also shown that chitosan membranes made with pure/sulfonated silica exhibited better proton conductivity and water uptake than those made without this modification. Chitosan membranes are commonly modified with silica nanoparticles to enhance their mechanical strength, stability, and barrier properties. The addition of silica can improve the overall performance of the membrane by reducing the permeability of certain molecules, including methanol [
21,
22]. The chitosan structure has two major groups: the amino and the hydroxy groups, which makes it easy to modify. Depending on the modification process, chitosan can undergo physical and chemical transformations [
23]. Chemical modification can be performed on either the amino or the hydroxy groups depending on the reaction [
23]. Although the primary group of chitosan reacts actively to the amino group, it is less reactive than the secondary group. When a chemical modification is carried out on the amino group, it will be labelled as N, while it will be O modified on the other side. Physical methods can be utilized to modify chitosan, such as mechanical grinding, ultrasonic treatment, and ionizing radiation [
24]. DMFC utilizes different types of membranes based on their morphological attributes. These include thick, thin, layered, porous, and pore-filled membranes [
25]. Although the properties of chitosan can be modified to improve its suitability for fuel cells, membrane morphology can still have a significant impact on its performance. For example, DMFC's thin membranes are prone to experiencing high methanol crossover when compared to thick ones.