## 1 Introduction  
Sarin is a nerve agent that caused massive casualties during World War I and II [1]. Since the Chemical Weapon Convention entered into force, the safe disposal of chemical warfare agents (CWAs) stockpiles has become a major challenge. In an attempt to dispose of the CWAs, various methods, e.g., incineration [2], hydrolysis [3; 4; 5], chemical reaction [6; 7; 8; 9], photolysis [10; 11; 12], etc., have been used. Among the commonly used disposal methods, thermocatalytic decomposition is one of the more efficient and low-cost approaches. During the thermocatalytic decomposition of CWAs, a catalyst must be used to enhance the removal efficiency. Thus, from the perspective of CWAs disposal, the lifetime of a catalyst is one of the most important parameters used in the evaluation of a catalyst's performance. It is customary to refer to the protection time as the catalyst's lifetime when 100% conversion is accomplished [13; 14]. It is worth noting that in laboratory research, dimethyl methylphosphonate (DMMP) is often used as a simulation of sarin, it exhibits low toxicity while possessing a similar structure with sarin. Among the various catalysts, metal oxides are commonly applied as catalysts for the thermocatalytic decomposition of DMMP, whereby they cleave the P\(-\)OCH\({}_{3}\) and P\(-\)CH\({}_{3}\) bonds [15; 16; 17]. Generally, P\(-\)OCH\({}_{3}\) could be easily broken by single valent metal oxides, such as Al\({}_{2}\)O\({}_{3}\)[18], MgO [19], ZnO [20], Y\({}_{2}\)O\({}_{3}\)[21], etc. For instance, the research on the thermocatalytic decomposition of DMMP on Al\({}_{2}\)O\({}_{3}\)[18] has shown that one of the methoxy bonds in DMMP was removed at approximately 200 \({}^{\circ}\)C, while the other methoxy bond was removed at 300 \({}^{\circ}\)C. However, the P\(-\)CH\({}_{3}\) bond remained intact on the surface of Al\({}_{2}\)O\({}_{3}\) even at temperatures above 400 \({}^{\circ}\)C. Such an observation was expected since the P\(-\)CH\({}_{3}\) bond is typically resistant to cleavage during thermocatalytic decomposition, which also happened for other single valent metal oxide catalysts, such as magnesium oxide and lanthanum oxide. As such, based on the literature, utilizing single valent metal oxide catalysts in the thermocatalytic decomposition process is inadequate to achieve full decomposition of DMMP. In contrast, it was recently shown that multivalent metal oxide catalysts are more favorable in the decomposition of DMMP, especially in the cleavage of P\(-\)CH\({}_{3}\) bond. Iron oxides have the unique ability to activate the P\(-\)CH\({}_{3}\) bond at room temperature. This phenomenon was attributed to the existence of a low energy pathway for the oxidative cleavage of P\(-\)CH\({}_{3}\) bond due to Fe(III)/Fe(II) redox couple [16; 22]. Similarly, multivalent manganese oxide [14] and copper oxide catalysts [15; 23] show scission of P\(-\)OCH\({}_{3}\) and P\(-\)CH\({}_{3}\) bonds. Being an important rare-earth metal oxide material, multivalent CeO\({}_{2}\) possesses an outstanding oxygen storage/release capacity with reversible redox variations between Ce\({}^{3+}\)/Ce\({}^{4+}\), as well as the formation and removal of oxygen vacancies [24], which makes it appealing in various applications such as catalysis, sensing, electrochemistry, optics, and biomedical applications [25; 26; 27; 28; 29]. [PERSON] et al. studied the room temperature decomposition of DMMP based on a series of alumina-supported cerium and iron oxide catalysts, and the optimal impregnation ratio of these two metals was obtained at the maximum decomposition degree of DMMP [30]. Based on further research, the incomplete decomposition mechanism of DMMP at room temperature based on alumina-supported cerium catalyst was revealed [31]. [PERSON] et al. reported DMMP decomposition on fully oxidized and partially reduced ceria films and reaction mechanism for DMMP decomposition on CeO\({}_{2}\)[32]. [PERSON] et al.