ABSTRACT
Graphene oxide has been widely used in the oxidative degradation of environmental pollutants. However, its catalytic role can be questioned as graphene oxide with oxygen-containing functional groups may also act as reactant in oxidative reactions. Herein, hydrogel composites loaded with multilayered graphene platelets showed excellent catalytic performance for the reduction of a wastewater organic pollutant (methylene blue) under NaBH4, which proved the catalytic role of multilayered graphene platelets. The liquid-based direct exfoliation method was used to prepare two-dimensional materials, which is compatible with other liquid phase methods to prepare nanomaterials. Hydrogel composites composed of multilayered graphene platelets, silver nanoparticles, and polyacrylic acid hydrogels were synthesized in water solution under irradiation with ultraviolet light, demonstrating the advantages of synthesizing nanocomposites using the liquid-based direct exfoliation method.
ABSTRACT
The capability of graphene-based biosensors used to detect biomolecules, such as DNA and cancer marker, is enormously affected by the quality of graphene. In this work, high quality and cleanness graphene were obtained by CVD based on acetic acid (AA) and ammonium persulfate (AP) pretreated copper foil substrate. Hall effect devices were made by three kinds of graphene which were fabricated by CVD using no-treated copper foil, AA pre-treated copper foil and AP pre-treated copper foil. Hall effect devices made of AA pre-treated copper foil CVD graphene and AP pre-treated copper foil CVD graphene can both enhance the sensitivity of graphene-based biosensors for DNA recognition, but the AA pre-treated copper foil CVD graphene improves more (≈4 times). This may be related to the secondary oxidation of AP pre-treated copper foil in the air due to the strong corrosion of ammonium persulfate, which leads to the quality decrease of graphene comparing to acetic acid. Our research provides an efficient method to improve the sensitivity of graphene-based biosensors for DNA recognition and investigates an effect of copper foil oxidation on the growth graphene.
ABSTRACT
Thin films with large compressive residual stress and low interface adhesion can buckle and delaminate from relatively rigid substrates, which is a common failure mode of film/substrate interfaces. Current studies mainly focused on the geometry of various buckling patterns and related physical origins based on a static point of view. However, fundamental understanding of dynamic propagation of buckles, particularly for the complicated web buckles, remains challenging. We adopt strained two-dimensional MoS2 thin films to study the phenomenon of web buckling because their interface adhesion, namely van der Waals interaction, is naturally low. With a delicately site-controlled initiation, web buckles can be triggered and their dynamic propagation is in situ observed facilely. Finite element modeling shows that the formation of web buckles involves the propagation and multilevel branching of telephone-cord blisters. These buckled semiconducting films can be patterned by spatial confinement and potentially used in diffuse-reflective coatings, microfluidic channels, and hydrogen evolution reaction electrodes. Our work not only reveals the hidden mechanisms and kinematics of propagation of web buckles on rigid substrates but also sheds light on the development of semiconducting devices based on buckling engineering.
