the dangling bonds. This saturation reduces the interface defect state, where the recombination takes place. Dielectric layer passivation Passivation by a dielectric layer on the top of crystalline silicon (c-Si) wafer, also called "tunnel passivation" is one of the passivation techniques used most widely in PV technology. This technique combines both chemical passivation and field-effect passivation. This strategy is based on the formation of a dielectric layer (mostly silicon dioxide SiO2, aluminum oxide Al2O3, or silicon nitride (SiNx) on the top of the c-Si substrate be the mean of thermal oxidation or other deposition techniques such as atomic layer deposition (ALD). In the case of the formation of SiOx by thermal oxidation, the process acts as chemical passivation since, on the one hand, the formation of the oxide layer reacts with the dangling bonds on the surface wherein it reduces the defects states at the interface. On the other hand, since there are fixed charges (Qf) in the dielectric film, these fixed charges establish an electric field that repels one type of charge carrier and accumulates the other type at the interface. This repletion assures reducing one type of the charge carriers concentration at the interface wherein the recombination decreases. Applications Catalysis In experiments by Yunteng Qu et al., dangling bonds on graphene oxide were used to bind single metal atoms (Fe, Co, Ni, Cu) for applications in catalysis. Metal atoms were adsorbed by oxidizing metal from a foam and coordinating the metal ions to the dangling bonds on the oxygen of the graphene oxide. The resulting catalyst had a high density of catalytic centers and showed high activity, comparable to other non-noble metal catalysts in oxygen reduction reactions while maintaining stability in a wide range of electrochemical potential, comparable to Pt/C electrodes. Ferromagnetic polymers An example of an organic ferromagnetic polymer is presented in an article by Yuwei Ma et al.: by cutting with ceramic scissors or stretching a piece of Teflon tape, a network of strongly coupling dangling bonds arises on surfaces where the polymer was broken (from cutting or in strain-induced cavities). In the case of weak structural deformation, where only very few dangling bonds are formed, the coupling is very weak and a paramagnetic signal is measured in EPR analysis. Annealing Teflon under an argon atmosphere at 100 °C to 200 °C results also in ferromagnetic properties. However, annealing close to the melting temperature of Teflon