本研究以化學氣相沉積法，合成高品質石墨烯薄膜，並成功藉由石墨烯轉移支撐層作為鉬前驅物，直接成長二硫化鉬於石墨烯上，形成異質結構，應用於光催化二氧化碳還原。此成長方式和粉末作為前驅物的方法相比，因為不需要去除支撐層，除了能減少製程的步驟與時間，更可有效地避免粉末前驅物不易成核於石墨烯上的問題。經由拉曼光譜儀鑑定，光譜顯示出石墨烯及二硫化鉬之特徵峰，證實二硫化鉬/石墨烯異質結構成功被合成。
本研究分別以1 mM、2.5 mM以及5 mM三種不同濃度的前驅物，合成二硫化鉬/石墨烯異質結構。透過原子力顯微鏡檢測異質結構之厚度，觀測到二硫化鉬厚度約為一至三層。藉由X射線光電子能譜分析，比較鉬原子峰值位置，顯示異質結構往低束縛能位移，表示有電子轉移至鉬原子端，證實有電子轉移之機制。
此外，本研究亦探討異質結構對於光催化二氧化碳效率的提升。三種濃度所合成之異質結構，在產物的選擇性發生改變，其原因可能來自於二硫化鉬層數之改變。量子轉換效率於濃度2.5 mM與5 mM分別提高二倍及四倍，其效率提升之原因可能來自於石墨烯／二硫化鉬異質結構，降低二硫化鉬載子複合率，幫助電子電洞分離，達到提高催化活性之目的。

In this research, we achieved direct growth of MoS2/graphene heterostructure via chemical vapor deposition (CVD) method as photocatalyst for photocatalytic carbon dioxide reduction (CO2RR) by utilizing graphene transfer supporting layer as molybdenum precursor. Compared to conventional powder-based CVD growth method, this method could simplify manufacturing steps and effectively solve the difficulties of powder precursor nucleating on graphene. Raman spectra of synthesized thin film clearly show the characteristic peaks of graphene and MoS2, indicating the successful synthesis of MoS2/graphene heterostructure.
In this study, 1 mM, 2.5 mM and 5 mM precursors concentration are used to synthesize MoS2/graphene heterostructure, respectively. By AFM analysis, we could observe that the thickness of MoS2 vary from monolayer to tri-layer. In XPS spectra, we noticed that the MoS2/graphene heterostructure Mo peaks shifted to lower binding energy compared with pure MoS2. The shift could assign to charge transfer to molybdenum atom. Moreover, We found that the CO2RR selectivity of products changed when precursor of different concentration was utilized. This result might result from the changes of number of layers of MoS2. Quantum efficiency of CO2RR doubled and quadrupled while using 2.5 mM and 5 mM precursor, respectively. The improvement of efficiency might be attributed to the heterostructure could facilitate the separation of excited electron-hole pair, which could reduce the possibility of carrier recombination and enhance photocatalytic activity.

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