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Organometal halide (OMH) perovskites are highly promising for photovoltaic (PV) and other applications. However, their instability toward environmental factors such as humidity presents a major challenge in their potential commercial use. In this study, we developed a method to modify the surface of CH 3 NH 3 PbI 3 perovskite films by spin coating oleic acid (OA) to create a water resistant layer that results in enhanced stability and PV performance. The OA-surface passivated perovskites were studied using FT-IR spectroscopy, UV−vis absorption spectroscopy, and X-ray diffraction (XRD). The samples were aged in dark humid air at ∼76% relative humidity (RH) for 4 weeks. The surface passivated films showed minimal signs of decomposition, and the PV devices showed better performance than the unpassivated devices. A possible explanation is the carboxyl group (−COO − ) of OA binds to surface Pb 2+ and/or CH 3 NH 3 + to both passivate these surface defect sites, resulting in the formation of a thin layer of OA with their hydrophobic tail away from the perovskite film surface that effectively prevents water molecules from reaching the perovskite.

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ABSTRACT:A new carrageenan based chelating copolymer sorbent was prepared by gamma radiation induced copolymerization and crosslinking of kappa-carrageenan (kCar) and acrylic acid (AAc). The swelling characteristics of the prepared copolymer were investigated by studying the effect of time, pH, and ionic strength of the swelling medium. The sorption capacities of the chelating copolymer for Fe, Pb, Mn, Zn, Cu, Sr, Cd, and Al were 172, 202, 202, 216, 221, 230, 239, and 244 mg/g respectively. The Freundlich and Langmuir adsorption isotherms were used to validate the metal uptake data and heats of adsorption for the investigated metal ions were calculated. The re-use experiment showed that the prepared hydrogel could be regenerated upto at least 10 times. Because of the promising data collected from bench scale experiments, the prepared copolymer was examined as chelating sorbent to improve the quality of some groundwater resources.

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A series of functional copolymer hydrogels composed of carboxymethyl cellulose (CMC) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) were synthesized using c-radiations-induced copolymerization and crosslinking. Preparation conditions were optimized, and the swelling characteristics were investigated. The ability of the prepared hydrogels to recover some toxic metal ions from their aqueous solutions was studied. The prepared hydrogel showed a great capability to recover metal ions such as: Mn þ2 , Co þ2 , Cu þ2 , and Fe þ3 from their solutions. The data revealed that the chelating ability of the prepared hydrogels is mainly dependent on their internal composi-tion, in addition to the physical properties of the metal ion solution such as pH and metal ion concentration. The data show that the chelating ability of the prepared hydrogels increases by increasing the AMPS content in the hydrogel as well as the increment in the pH of the solution and the metal ion concentration. The prepared CMC/AMPS copolymer hydrogels are chemically stable enough to be reused for at least five times with the same efficiency.

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