Chemical Vapor Deposition (CVD) is a technique for depositing thin films of material onto substrates through chemical reactions involving vapor species. The specific reactions and processes in a CVD reactor are influenced by various factors, including system setup, reactor design, gas feedstock and ratios, reactor and gas partial pressures, reaction temperature, and growth time. CVD is a widely employed bottom-up method for producing few-layer and single-layer graphene films. The initial use of thermal CVD on metals was reported in 1966, demonstrating the growth of highly crystalline graphite films on nickel substrates. Subsequently, a single layer of graphite was deposited using CVD on a platinum surface through hydrocarbon decomposition at 530 °C . Following the isolation of graphene in 2004, the potential of CVD for graphene film growth was successfully demonstrated with the use of Low-Pressure CVD (LPCVD) to grow graphene on iridium . The popularity of CVD for graphene synthesis is attributed to its straightforward setup in research labs, proven long-term use in industrial settings, and scalability. Moreover, considering ecological and cost factors, CVD is among the most effective methods for synthesizing graphene-based materials. Various CVD methods are now available for synthesizing graphene, categorized based on processing parameters such as temperature, pressure, precursor type, gas flow, wall/substrate temperature, deposition time, and activation method, as illustrated in Figure For CVD graphene deposition, a Cu metal substrate is put into the furnace tube, normally made of quartz, and heated under hydrogen flow at low vacuum or atmospheric pressure. The high temperature anneals the substrate and increases its grain size, usually in the range between 1-10 m , as well as reduces the metal oxide film on the substrate surface . During growth, carbon is usually provided by mixing a hydrocarbon gas, such as methane (CH4), with hydrogen. The gases are then passed through the reactor at a pre-determined ratio. This can be done by either changing the reactor pressure or by the addition of an inert diluent gas such as argon (Ar) or nitrogen (N). At the end of reaction, the furnace is usually turned off and allowed to cool down to room temperature under a gas flow, such as H2, H2 + Ar. The purpose of this step is to prevent the aggregation of deposited carbon, which may give rise to multi-layer graphene or even bulk graphite. It henceforth plays its role in realizing a continuous graphene monolayer on the surface of metals.