Carbon nanomaterials doping

As aforementioned, the introduction of carbon nanomaterials is an effective strategy to take on some of the contemporary challenges in the field of DSSCs. In particular, enhanced charge injection and charge transport processes in carbon nanomaterial-doped electrodes, efficient carbon nanomaterial-based, iodine-free, quasi-solid state electrolytes, and the use of novel nanographene hybrids as dyes are some of the most stunning milestones. All of these milestones are considered as solid proof for the excellent prospect of carbon nanomaterials in DSSCs. The major goal of this chapter is to... 

Fig. 18.3 Current versus applied voltage characteristics for DSSCs prepared with 0.0 0.2 0A 0.6 0.8 different carbon nanomaterials doped...

After Iijima pointed out the extraordinary strength of carbon nanotubes [204], and after their Young s modulus were measured [205], scientists and engineers have been interested in the mechanical properties of CNTs and other carbon nanomaterials. In this section, we will review the effect of defects and doping on the mechanical properties of carbon nanomaterials. 

Among the electrochemical techniques and characterization tools, vibrational and optical spectroscopies have been important. Electrochemical charge transfer, an important process in electrochemistry, influences not only the electronic structure of the materials but also their vibrational and optical properties, which are all dependent on the concentration of electrons and holes found in the solid. Therefore, valuable data can be obtained when electrochemistry and in situ Raman spectroscopy are applied simultaneously under the heading of spectro-electrochemistry. Such investigations have been carried out extensively on carbon nanomaterials in order to investigate the effects of electron and hole doping. 

Recently, the research on exploring the use of carbon nanomaterials as metal-free catalysts has been one of the major subjects for the fuel cell research. Owing to their wide availability, environmental acceptability, corrosion resistance, and unique surface and bulk properties, carbon nanomaterials are ideal candidates for metal-free ORR catalysts. In this context, we have demonstrated that vertically aligned nitrogen-doped carbon nanotube (VA-NCNTs) array exhibited three times higher ORR electrocatalytic activity and better long-term operation durability... 

Carbon nanomaterials, and especially N-CNTs, have long been used as catalyst support in the held of heterogeneous catalysis as menhoned above while their direct use as metal-free catalysts has been reported only recently. Some of the catalytic reachons carried out on heterogeneous heteroatom-doped carbon nanomaterials are listed in Table 9.3. One can see that N-CNT as metal-free catalyst has received an ever-increasing academic interest over... 

Yang, Z., Nie, H., Chen, X. et al. 2013. Recent progress in doped carbon nanomaterials as effective cathode catalysts for fuel cell oxygen reduction reaction. J. Power Sources 236 238-249. 

Integration of nanostructured Si with carbon nanomaterials such as carbon paper, CNTs, or graphene in the porous electrodes is a useful approach to improve the electrochemical performance of Si. In this composite structure, the void space accommodates the volume expansion of Si, and the carbon nanomaterials compensate for the low intrinsic electronic conductivity of Si furthermore, the overall electrode structure is allowed to maintain stable SEI layers formed on the carbon surfaces. An example is shown in Figure 8.10 [13]. It is prepared by simple mixing of aqueous dispersions including Si and N-doped carbons. Due to electrostatic interactions between the N-doped sites of graphitic carbons and surface hydroxyl functionalities of Si, this composite can be prepared at room temperature for effective encapsulation by solution mixing. The interaction between N-CNTs and Si particles is very stable. As a result, the composites display superior capacity retention of 79.4% after 200 cycles, and excellent rate capability of 914 mAh/g is observed at a 10 C rate [13]. 

The most prominent nanomaterials for bioanalysis at present are semiconductor QDs. Rare-earth doped upconverting nanocrystals and precious metal nanoparticles are becoming increasingly popular, yet they are still far from reaching the level of use of QDs. Other luminescent nanoparticles like carbon-based nanoparticles start to appear, but the synthesis and application of these materials are still in their infancy and not significant for practitioners in the field of bioanalysis. 

On the other hand, liquid phase deposition (LPD) has been demonstrated as a flexible wet chemical method for preparing metal oxide nanostructured films on electrode surfaces. By the LPD process, electroactive titanium dioxide (Ti02) films were prepared on graphite, glassy carbon and ITO. The electrochemical properties of such LPD Ti02 films were dependent upon the film thickness controlled by the deposition time. The LPD technique was easily combined with other techniques, e.g., seed-mediated growth, which could provide metal/metal oxide composite nanomaterials. Moreover, hybrid nanostructured films were facilely obtained by doping dyes, surfactants and other... 

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