“…Figure S12a shows a TEM image of PDA with irregular contours, the corresponding electron diffraction (ED) of the PDA can be seen in Figure S12b, and the ED image is an average of images taken at different PDA positions and corresponds to an amorphous material, which shows large and few peaks in ED. The peaks extracted from ED can be seen in Figure S12c in the inserted graph and their respective distances are 3.65 Å (2.74 nm –1 ), 2.02 Å (4.95 nm –1 ), and 1.17 Å (8.56 nm –1 ) and these distances correspond to amorphous carbon. , Figure S12c shows the graph corresponding to the electron pair distribution function (ePDF) of the PDA and the distances measured again correspond to amorphous carbon, 1.37, 2.54, 3.79, and 4.91 Å.…”
Electrochemical paper-based analytical devices represent an important platform for portable, low-cost, affordable, and decentralized diagnostics. For this kind of application, chemical functionalization plays a pivotal role to ensure high clinical performance by tuning surface properties and the area of electrodes. However, controlling different surface properties of electrodes by using a single functionalization route is still challenging. In this work, we attempted to tune the wettability, chemical composition, and electroactive area of carbon-paper-based devices by thermally treating polydopamine (PDA) at different temperatures. PDA films were deposited onto pyrolyzed paper (PP) electrodes and thermally treated in the range of 300−1000 °C. After deposition of PDA, the surface is rich in nitrogen and oxygen, it is superhydrophilic, and it has a high electroactive area. As the temperature increases, the surface becomes hydrophobic, and the electroactive area decreases. The surface modifications were followed by Raman, X-ray photoelectron microscopy (XPS), laser scanning confocal microscopy (LSCM), contact angle, scanning electron microscopy (SEM-EDS), electrical measurements, transmission electron microscopy (TEM), and electrochemical experiments. In addition, the chemical composition of nitrogen species can be tuned on the surface. As a proof of concept, we employed PDA-treated surfaces to anchor [AuCl 4 ] − ions. After electrochemical reduction, we observed that it is possible to control the size of the nanoparticles on the surface. Our route opens a new avenue to add versatility to electrochemical interfaces in the field of paper-based electrochemical biosensors.
“…Figure S12a shows a TEM image of PDA with irregular contours, the corresponding electron diffraction (ED) of the PDA can be seen in Figure S12b, and the ED image is an average of images taken at different PDA positions and corresponds to an amorphous material, which shows large and few peaks in ED. The peaks extracted from ED can be seen in Figure S12c in the inserted graph and their respective distances are 3.65 Å (2.74 nm –1 ), 2.02 Å (4.95 nm –1 ), and 1.17 Å (8.56 nm –1 ) and these distances correspond to amorphous carbon. , Figure S12c shows the graph corresponding to the electron pair distribution function (ePDF) of the PDA and the distances measured again correspond to amorphous carbon, 1.37, 2.54, 3.79, and 4.91 Å.…”
Electrochemical paper-based analytical devices represent an important platform for portable, low-cost, affordable, and decentralized diagnostics. For this kind of application, chemical functionalization plays a pivotal role to ensure high clinical performance by tuning surface properties and the area of electrodes. However, controlling different surface properties of electrodes by using a single functionalization route is still challenging. In this work, we attempted to tune the wettability, chemical composition, and electroactive area of carbon-paper-based devices by thermally treating polydopamine (PDA) at different temperatures. PDA films were deposited onto pyrolyzed paper (PP) electrodes and thermally treated in the range of 300−1000 °C. After deposition of PDA, the surface is rich in nitrogen and oxygen, it is superhydrophilic, and it has a high electroactive area. As the temperature increases, the surface becomes hydrophobic, and the electroactive area decreases. The surface modifications were followed by Raman, X-ray photoelectron microscopy (XPS), laser scanning confocal microscopy (LSCM), contact angle, scanning electron microscopy (SEM-EDS), electrical measurements, transmission electron microscopy (TEM), and electrochemical experiments. In addition, the chemical composition of nitrogen species can be tuned on the surface. As a proof of concept, we employed PDA-treated surfaces to anchor [AuCl 4 ] − ions. After electrochemical reduction, we observed that it is possible to control the size of the nanoparticles on the surface. Our route opens a new avenue to add versatility to electrochemical interfaces in the field of paper-based electrochemical biosensors.
“…In our numerical calculations, we assume the values of for silicon as given in Ref. 52 . Figure 1 Schematic of a distorted silicene honeycomb lattice, lattice vectors, and inter-atomic couplings.…”
A tight-binding (TB) Hamiltonian is derived for strained silicene from a multi-orbital basis. The derivation is based on the Slater–Koster coupling parameters between different orbitals across the silicene lattice and takes into account arbitrary distortion of the lattice under strain, as well as the first and second-order spin–orbit interactions (SOI). The breaking of the lattice symmetry reveals additional SOI terms which were previously neglected. As an exemplary application, we apply the linearized low-energy TB Hamiltonian to model the current-induced spin accumulation in strained silicene coupled to an in-plane magnetization. The interplay between symmetry-breaking and the additional SOI terms induces an out-of-plane spin accumulation. This spin accumulation remains unbalanced after summing over the Fermi surfaces of the occupied bands and the two valleys, and can thus be utilized for spin torque switching.
“…The 5-8-5 defect is frequently observed in the di-vacancy configuration in graphene samples [23][24][25][26][79][80][81][82], which can be created either by coalescence of two single vacancies or by removing two neighboring atoms as sketched in figure 4(b). Previous simulations indicate that the formation energy of a di-vacancy is of the same order as that of a single vacancy (about 8 eV) [67,68].…”
The fusion processes of structures consisting of various combinations between sumanene and corannulene, leading to the formation of graphene nanoribbons (GNRs) under heating are simulated by density-functional-based tight-binding molecular dynamics. Distinct stages are unraveled in the course of GNR formation. Firstly, the carbon fragments coalescence into highly strained framework. Secondly, structural reconstruction invokes breaking most strained bonds to form a GNR structure containing numerous defects. Lastly, defects are remedied by the delicate ‘edge-facilitated self-healing’ process through two synergized edge-related effects: elevated mobility of defects and promoted structure reconstructions owing to the remarkable dynamics associated with edges. Importantly, detailed dynamics in the course of forming GNRs with defects and grain boundaries simulated in this work is valuable to provide better understanding at the atomistic scale of defect formation as well as self-healing in the context of the sp2 carbon network. In particular, edges play important roles in not only generating Stone–Wales (SW), 5-8-5 types of defects, 8-5-5-8 and pentagon–heptagon grain boundaries. In addition, our simulations predict the existence of one novel defect, coined as the Inverse SW defect, which is to be confirmed in future experimental studies. This study of dynamic structural evolution reveals that edges are prone to intrinsic and extrinsic modifications such as atomic-scale defects, structural distortions and inhomogeneity.
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