Among the existing commercial cathodes, Ni-rich NCM are the most promising candidates for next-generation LIBs because of their high energy density, relatively good rate capability, and reasonable cycling performance.

Photocatalysis is a more proficient technique that involves the breakdown or decomposition of different organic contaminants, various dyes, and harmful viruses and fungi using UV or visible light solar spectrum.

In this work, using the Quantum ESPRESSO package, density functional theory was used to study the effects of different metal dopants on the structural and electronic properties of tetragonal α-PbO. Tetragonal α-PbO has attracted attention due to its application in various optoelectronic devices. However, in order to apply it in these technologies suitably, its properties have to be improved since it has low electronic conductivity. In this study, nine different metals from alkali metals, p-block metals, and 3d-transition metals have been used as dopants to investigate its electronic properties. Moreover, the performance of four pseudopotentials was tested. Via the partial density of state and band structure calculations, an indirect bandgap was found for pristine α-PbO. The generalized gradient approximation of the Perdew–Burke–Ernzerhof exchange correlation with ultrasoft pseudopotential gives 1.75 eV for pristine α-PbO, which decreased during the incorporation of different metal dopants. Depending on the position of the Fermi level and impurity energy level in metal doping, the n- or p-type conductivity has been identified. The calculated partial density of states shows the contribution of orbital states of dopants to the partial density of states. The valence band maximum is mainly made of O-2p states whereas the conduction band minimum is dominated by Pb-6p states in undoped α-PbO. The calculated lattice constants were a = b = 3.997 Å and c = 5.220 Å, which are in best agreement with the experimental values. The computational study verified that doping various metals had a significant effect on the structural and electronic properties of α-PbO.

In recent days, metallic oxide semiconductor nanoparticles have drawn attention to the photocatalytic degradation of organic pollutants. In the present work, undoped and different metals (Sn, Co, Cu, Ni, and Li)-doped of α-PbO nanoparticles were successfully synthesized by a facile chemical precipitations method. The obtained nanoparticles were further studied by using different characterization techniques. The XRD results confirmed that the prepared nanoparticles were a tetragonal, α-PbO phase crystal structure without mixing other PbO phases. The obtained optical band gaps from UV-Vis DRS analysis were 2.03 eV, 2.68 eV, 1.61 eV, 1.78 eV, 1.67 eV, and 2.00 eV for pristine α-PbO, Sn, Co, Cu, Ni, and Li doped α-PbO respectively. From the PL emission, the lowest PL intensity of the doped samples indicated the low recombination of the electron-hole pairs that improved the photocatalytic performance of pristine α-PbO. SEM and EDX were used to analyze the surface morphology and composition of the synthesized nanoparticles, respectively. The photocatalytic activities of the prepared nanoparticles were assessed through the degradation of the Methylene Blue (MB) dye under visible light irradiation. The UV-Visible spectrophotometer analysis showed that the MB dye concentration decreased as the irradiation time varied from 20 to 100 min. The results showed that within 100 minutes, the Sn-doped α-PbO nanoparticles possessed the maximum degradation efficiency compared to other metal-doped α-PbO nanoparticles, with 100 % MB dye degradation compared to 94.76 % by pristine α-PbO. This was due to the increased visible light harvesting, which aided in the photocatalytic degradation of MB dye.

Nanowires (NWs) are 1D nanostructures with unique and wonderful optical and electrical properties. Due to their highly anisotropic shape and enormous index of refraction, they behave as optical antennae with improved absorption and emission properties, and thus better photovoltaic cell efficiency compared to a planar material with equivalent volume. Implying important advantages of reduced material usage and cost as well as due to its direct bandgap and its flexibility for designing solar cells, we choose to review III–V NWs. Their bandgap can easily be tunable for growing on the cheapest Si substrate. The recent developments in NW-based photovoltaics with attractive III–V NWs with different growth mechanisms, device fabrication, and performance results are studied. Recently, III–V NW solar cells have achieved an interesting efficiency above 10%. GaAsP NW has achieved 10.2%; InP NW has achieved 13.8%; GaAs NW has achieved 15.3%; and moreover the highest 17.8% efficiency is achieved by InP NW. While the III–V NW solar cells are much more vital and promising, their current efficiencies are still much lower than the theoretically predicted maximum efficiency of 48%. In this review, the chapter focused on the synthesis processes of III–V nanowires, vapor-liquid-solid growing mechanisms, solar light harvesting of III–V nanowire solar cells, and designing high-efficiency and low-cost III–V nanowire solar cells.

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