Inorganic cesium lead bromoiodide based planar perovskite solar cells with ZnO electron transport layers are deposited using one step spin coating.

The development of cost-effective, functional materials that can be efficiently used for sustainable energy generation is highly desirable. Herein, a new molecular precursor of bismuth (tris(selenobenzoato)bismuth(III), [Bi(SeOCPh) 3 ]), has been used to prepare selectively Bi or Bi 2 Se 3 nanosheets via a colloidal route by the judicious control of the reaction parameters. The Bi formation mechanism was investigated, and it was observed that the trioctylphosphine (TOP) plays a crucial role in the formation of Bi. Employing the vapor deposition method resulted in the formation of exclusively Bi 2 Se 3 films at different temperatures. The synthesized nanomaterials and films were characterized by p-XRD, TEM, Raman, SEM, EDX, AFM, XPS, and UV–vis spectroscopy. A minimum sheet thickness of 3.6 nm (i.e., a thickness of 8–9 layers) was observed for bismuth, whereas a thickness of 4 nm (i.e., a thickness of 4 layers) was observed for Bi 2 Se 3 nanosheets. XPS showed surface oxidation of both materials and indicated an uncapped surface of Bi, whereas Bi 2 Se 3 had a capping layer of oleylamine, resulting in reduced surface oxidation. The potential of Bi and Bi 2 Se 3 nanosheets was tested for overall water-splitting application. The OER and HER catalytic performances of Bi 2 Se 3 indicate overpotentials of 385 mV at 10 mA cm –2 and 220 mV, with Tafel slopes of 122 and 178 mV dec –1 , respectively. In comparison, Bi showed a much lower OER activity (506 mV at 10 mA cm –2 ) but a slightly better HER (214 mV at 10 mA cm –2 ) performance. Similarly, Bi 2 Se 3 nanosheets were observed to exhibit cathodic photocurrent in photoelectrocatalytic activity, which indicated their p-type behavior.

In an era of unprecedented urbanization, population and industrial growth pressure is serious threat for the water management in Pakistan in present days. Water pollution from raw sewage, industrial wastes, and agricultural runoff limited natural fresh water resources in the country. Human health is facing serious problems due to deteriorating drinking water quality. Current review paper provides an insight to the water quality problems in Pakistan with an attempt to emphasize the challenges of water laws enforcement. Although Pakistan has developed many water laws the state of implementation is dominant, intermediate pollution crises are still remaining. We could come to the conclusion that strictly enforcement is compulsory for water environment regulations in Pakistan. Moreover, it is necessary to establish a reliable risk assessment system for water quality, human health and ecological safety.

Resolution of resources and environmental crises requires an efficient separation technologies, consequently, scientists and engineers are working vigorously for ideal separation materials. Laminar graphene oxide (GO) is a two-dimensional (2D) material offers considerable interest in this field due to its single atomic layer thickness, good stability, chemical inertness, and variety of functional groups. Recently, GO have emerged as a novel membrane material for molecular and ionic separation of gases, solvent, water, and desalination applications. This tutorial review aims to discuss the various approaches used to control the stacking of GO-based membrane with emphasis of advantages and drawbacks associated with each approach. Further, attention will also be given to describe the recent progress in GO based membranes for ionic and molecular separations. Meanwhile, challenges and opportunities will also be discussed in detail. We hope this review expected to provide a compact source of information that will be of great interest to chemists, material scientists, physicists, and engineers working or planning to work in GO based membranes for separation applications.