Correlation between microstructure and surface chemistry of carbon nanofibers grown using different adhesive layers

Enhancing electrocatalytic activity in metallic thin films through surface segregation of carbon

“…We used DA and AA as analytes as we have studied the electrochemical activity of these biomolecules on carbon nanofibers grown on similar systems containing these adhesion layers in previous reports. 8,16 Fig. 3 Cyclic voltammetry responses of Ti/Si and Cr/Si before and after annealing in 1 mM ascorbic acid (A) and (C) and 100 mM dopamine (B) and (D) in the PBS electrolyte at a scan rate of 100 mV s À1 .…”

“…In our previous reports, we evaluated the effect of Cr and Ti adhesion layers in addition to the catalyst layer on the surface chemistry and microstructure of CNFs. 7,16 The CNFs grown at the Cr and Ni interface showed a higher population density and a different CNF structure resembling herringbone patterns, whereas CNFs grown at the Ti and Ni interface had a bamboo-like structure and exhibited distinct electrochemical properties. 16,17 This pointed out that the role of the interfacial layer is critical and must be understood in detail.…”

“…7,16 The CNFs grown at the Cr and Ni interface showed a higher population density and a different CNF structure resembling herringbone patterns, whereas CNFs grown at the Ti and Ni interface had a bamboo-like structure and exhibited distinct electrochemical properties. 16,17 This pointed out that the role of the interfacial layer is critical and must be understood in detail. However, the comparison of the systems with different adhesion layers is difficult to realize when CNFs are present on the interface presenting the lack of susceptibility to the measurement of underlying layer activity.…”

Ni Drastically Modifies the Microstructure and Electrochemistry of Thin Ti and Cr Layers

“…Thin layers of Cr and Ti as adhesion layers covered by Ni as catalyst layer are among the commonly used interfacial metal stacks for growing carbon nanofibers (CNFs), graphene, nanowires, and semiconductor nanoparticles finding applications in various areas. − For growing carbon nanofibers, Ni provides the growth and nucleation sites through its surface step-edge sites acting as preferential growth centers for graphene layers and is known to act best as a catalyst at 600–700 °C. , Ti and Cr provide better adhesion capability by chemically binding with the substrate and through electrical contact owing to their partially filled d-orbital . Well known for their remarkable electrochemical sensing properties of biomolecules, , CNFs facilitate chemical interactions with the target molecules (ISR probes); nonetheless, the electrode’s electrochemical activity originates from both CNFs and interfacial metal layers.…”

“…Due to the varying inherent solubility profiles of common interstitial solutes (O, C, and N) in the Ni seed layer compared to those of Ti and Cr, − the presence of Ni will cause microstructural changes, likely leading to significant changes in their electrochemistry. These changes will not only affect the growth kinetics of CNFs but also promote/demote the formation of specific phases considered favorable for the EC activity. Despite the importance of the microstructural changes of the interface in the assessment of the structure–property relationships for carbon-based electrodes, there is a lack of information about these changes and their subsequent effects on the electrochemical properties.…”