The use of inert CH4 enabled us to selectively synthesize the single-layered porous graphene materials. Density functional (bottom) Energy level diagrams of the initial CH4 activation on Al site and Al site of γ-Al2O3 (100) surface during CH4-CVD for the synthesis of NPGs. theory (DFT) calculations coupled with experimental kinetic analysis using thermogravimetry (TG) techniques revealed that the dehydration and subsequent surface activation of γ-ANPs by CH4 are crucial in controlling surface chemistry. According to the DFT calculations, the original octahedral site (Al ) coordinated with six atoms of surrounding oxides affords a radical mechanism in the initial CH4 activation, with an activation energy (∆E ‡ ) of 270 kJ mol -1 . Further elimination of surface oxides eventually leads to more reactive tetrahedral sites (Al ). The surface with oxygen vacancies provides a favorable reaction pathway for proton transfer (PT) reactions via the Lewis acid/base mechanism, with a calculated apparent ∆E ‡ of 120 kJ mol -1 . This theoretical value agrees well with the experimental value of 124 kJ mol -1 obtained from the Arrhenius plot using the TG technique. This PT step is the kinetic bottleneck for the entire reaction. Subsequent PT results in the formation of surface methylene species (CH2*). DFT calculations also demonstrated that further carbon chain growth to form heavier aliphatic hydrocarbons by adding or inserting CH2* species is thermodynamically and kinetically feasible. θ-ANPs are also applicable as template materials. To improve the efficiency of the synthesis and quality of the resultant NPGs and achieve ideal 3D graphene materials, it is essential to finding new templates that realize (i) efficient catalytic activation of CH4 at lower reaction temperatures, (ii) better structural regularity of the resultant NPGs, and (iii) easy removal of the templates after the CVD process. CH4-CVD on nanostructured oxides, including γ-ANPs and zeolites, requires high temperatures above 800 °C for a sufficient rate of carbonization. Such a high temperature can easily damage the structural order over time. 101 Fig. shows the dependence of CH4 partial pressure on the rate of CH4-CVD carbonization on γ-ANP. We found that the rate of carbonization decreased when the reaction reached the single-layer carbonization on γ-ANPs. Faster carbonization through better surface catalysis, as shown in Fig. , is required to lower the reaction temperature and improve selectivity. Screening of catalysts using thermogravimetric analysis (TGA) is a promising approach.