Effect of graphene oxide flakes size and number of layers on photocatalytic hydrogen production

Abstract

The present study explored the correlation between the photocatalytic activity toward hydrogen production of the graphene-based materials and graphene oxide (GO) morphology. In this work we applied the technique based on the combination of time-dependent sonication and iterative centrifugation cascades, which were designed to achieve nanosheets size and the number of layers selection. First such obtained GO dispersions were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical spectroscopy. Those combined measurements showed that the intensity of the π-π peak at 230 nm seems to be very sensitive to the number of layers of nanosheets. Next, GO dispersions were used to establish influence of the size and the number of layers of GO flakes on the photocatalytic hydrogen production in the photocatalytic system, containing eosin Y as a sensitizer, triethanolamine as a sacrificial electron donor, and CoSO4 as precatalyst. The H2 production efficiency varied by a factor of 3.7 for GO dispersions sonicated for various amount of time. Interestingly it was found that too long ultrasound treatment had negative impact on the GO enhancement of hydrogen production which was related to the fragmentation of GO flakes. The photocatalytic system produced the highest amount of H2 when graphene oxide occurs as monolayers and efficiency becomes lower with the decrease of GO sheets size. Our results demonstrate the importance of optimizing the size and the number of layers of the GO flakes prior to preparation of GO-based materials.

NanoGraphene Clot: A New Fibrinogen-Mimic Hemostatic Material

“…To isolate the smaller one, a 0.4 mg/mL suspension was sonicated for 80 min with frequent vortex cycles, centrifuged (931 g or 2000 rpm for 40 min at 20 °C), and the supernatant was collected. This method of GO or GO- g -PEG size reduction has also been followed by Gonçalves et al and the groups of Kostarelos and Lewandowska-Andralojc . TEM analysis revealed a reduction in the size of the material to be 211 ± 83 nm (Figure c, more images are displayed in Figure S6).…”

“…GO- g -PEG 6K -NH 2 was synthesized using a two-step process. Initially, GO was prepared using the modified Hummer’s method. − The material contained oxygen-based functionalities, including carboxylic groups (1750–1720 cm –1 ), hydroxyl groups (3400–3200 cm –1 ), and epoxy groups (∼1100 cm –1 ), in addition to the phenyl CC groups of graphene at 1640–1600 cm –1 , as shown in Figure a. Several researchers point out that the carboxylic groups are present on the edges of graphene, while hydroxyl and epoxy groups on the basal plane .…”

Development of sustainable strontium ferrite graphene nanocomposite for highly effective catalysis and antimicrobial activity

“…4 B). Figure 4 C,D, respectively, depict GO and SF@GOC for clear topography scan with 3D views 18 . In SF@GOC , the immobilization-induced structural alterations are again quite clear.…”

Optimization of Graphene Oxide’s Characteristics with TOPSIS Using an Automated Decision-Making Process

“…The thickness of GO can have impact on the efficiency of certain devices such as solar cells [31]. Recently, the effects of the thickness of GO on some of its properties such as its friction [32] and hydrogen production [33] have been reported. However, these properties have not been correlated, yet.…”