## 1 Introduction
All electrochemical reactions occur within it. It consists of a gas diffusion layer (GDL), a cathode catalyst layer (CCL), an anode catalyst layer (ACL), and a membrane. The catalyst layer is a crucial part of it, mainly used to enhance the rate of the oxygen reduction reaction (ORR). The energy loss that occurs in the catalyst layer is called activation loss. The energy lost in the catalyst not only dissipates as heat but also leads to catalyst degradation, resulting in a loss of electrochemical surface area (ECSA) [13]. Catalyst degradation mainly involves the dissolution of platinum-based nanoparticles and the degradation of the catalyst support material. Specifically, the dissolution process can be further divided into platinum dissolution and redeposition, formation and reduction in platinum oxides, carbon corrosion, and the membrane precipitation of platinum ions [14]. All of these reactions are influenced by temperature. The proton exchange membrane (PEM) is a component in fuel cells that facilitates the transport of hydrogen ions from the anode to the cathode. The ohmic losses in a fuel cell are primarily caused by the ion conductivity of the membrane, which is influenced by the moisture content of the membrane [15]. The failure of the proton exchange membrane can be classified as either physical failure or chemical failure. Physical failure refers to damages such as cracks or ruptures that occur due to physical factors like airflow impact or stresses caused by changes in moisture content within the cell [16]. These damages are typically evident in the early stages of cell operation. Chemical failure, on the other hand,occurs over time due to the membrane's degradation caused by high temperature, high humidity, and acidic or alkaline conditions. It takes longer periods of usage to manifest chemical failure. The gas diffusion layer (GDL) in a fuel cell serves multiple functions. Its primary role is to distribute reactants evenly to the catalyst layer while providing mechanical support to both the proton exchange membrane and the catalyst. Additionally, the GDL facilitates electron conduction, heat dissipation, and water transport. In a fuel cell, concentration loss refers to the inability of the gas diffusion layer to meet the high mass flow requirements promptly. However, typically, fuel cells do not operate at current densities that result in concentration loss, and therefore, its impact on the overall fuel cell performance is minimal. Hence, when considering the rated power degradation of a fuel cell, the main focus is on catalyst layer degradation and proton exchange membrane degradation [17]. Researchers have conducted extensive work on identifying and predicting the degradation and decay of fuel cells. Currently, two main methods are used for fuel cell degradation modeling: semi-empirical methods and physical methods. Semi-empirical methods typically involve collecting a set of data in a reference state and directly fitting coefficients to be applied across all operating conditions of the fuel cell. These coefficients are often fixed values and independent of the actual operating conditions and electrochemical behavior of the fuel cell. As a result, these models cannot accurately predict degradation under different driving conditions. Physical methods, on the other hand, are based on transport equations and electrochemical reactions. These models require more detailed data compared to semi-empirical methods, but they provide more accurate results. However, certain parameters, such as the evolution of hydrogen gas content within the membrane over time, are difficult to measure and accurately estimate. Therefore, while physical models offer improved accuracy, some parameters remain challenging to measure or predict accurately [18]. The empirical and semi-empirical models currently used in the literature are mostly derived from the studies of [PERSON] et al. [19] and [PERSON] et al. [20].