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Sn-based perovskite solar cells (PSCs) featuring high performance and long-term stability are very challenging because Sn2+ is relatively prone to oxidation. Here, we have performed coadditive engineering with 5-ammonium valeric acid iodide (5-AVAI) for FASnI3-based perovskite films. From the morphological, structural, and elemental analyses, we observed that 5-AVAI affects the crystal growth of perovskites through its hydrogen bond with I– of the SnI6 4– octahedral. As a result, pinhole-free homogeneous and stable Sn-based perovskite films form over a large area with lower Sn4+ content. This made us able to enhance the power conversion efficiency (PCE) for Sn-based PSCs up to 7% in a 0.25 cm2 aperture area. Most importantly, the 5-AVAI added PSCs showed a record stability and maintained their initial PCE under 1 sun continuous illumination at maximum power point tracking for 100 h.

Atomic hydrogen storage by carbon nanotubes (CNTs) at atmospheric pressure is studied using Pd and La catalysts for dissociation of H 2 into atomic hydrogen and formation of defects on CNT surfaces, respectively. The defect sites on CNTs as adsorption sites of atomic hydrogen are prepared by oxidation pretreatment using a La catalyst. Pd catalysts are then deposited on CNT surfaces for dissociation of H 2 into atomic hydrogen, which then spills over to the defect sites. In the best case, 1.0 wt % hydrogen is stored in the defective CNT with Pd particles at 1 atm and 573 K. The hydrogen desorption in temperature programmed desorption (TPD) experiments started at 700-900 K, which agreed with the annealing temperatures of CNTs prior to hydrogen storage. Also, the amount of hydrogen stored in CNTs decreased with increasing annealing temperature. These results are ascribed to the crystallization of the defective structure of CNT into graphitic structure. The activation energies of 46.6, 87.3, and 129.8 kJ/mol derived from the desorption peaks of hydrogen in the defective CNT with Pd particles vary from 46.6 to 129.8 kJ/mol, depending on the annealing temperatures at 523, 623, and 773 K, respectively. The difference in the activation energies is probably due to the energies required for the recrystallization of the defect sites into the graphite structure.

High P-T Raman measurements of solid and fluid hydrogen to above 1100 K at 70 GPa and to above 650 K in 150 GPa range, conditions previously inaccessible by static compression experiments, provide new insight into the behavior of the material under extreme conditions. The data give a direct measure of the melting curve that extends previous optical investigations by up to a factor of 4 in pressure. The magnitude of the vibron frequency temperature derivative (dnu/dT)(P) increases by a factor of approximately 30 over the measured pressure range, indicating an increase in intrinsic anharmonicity and weakening of the molecular bond.