Organic-inorganic halide perovskites have rapidly grown as favorable materials for photovoltaic applications, but accomplishing long-term stability is still a major research problem. This work demonstrates a new insight on instability and degradation factors in CH3NH3PbI3 perovskite solar cells aging with time in open air. X-ray photoelectron spectroscopy (XPS) has been used to investigate the compositional changes caused by device degradation over the period of 1000 hrs. XPS spectra confirm the migration of metallic ions from the bottom electrode (ITO) as a key factor causing the chemical composition change in the perovskite layer besides the diffusion of oxygen. XPS results are in good agreement with the crystallographic marks. Glow discharge optical emission spectrometry (GD-OES) has also been performed on the samples to correlate the XPS results. Based on the experimental results, fundamental features that account for the instability in the perovskite solar cell is discussed.

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Ti3C2Tx MXene nanostructures have garnered attention for various catalytic applications due to their built-in electronic properties. Herein, we rationally design highly exfoliated two-dimensional Ti3C2Tx nanosheets (Tx= O, OH, and F)...

A one-pot, bottom-up assembly of a pyrimidine-containing porous-organic polymer (PyPOP) was conducted to homogenously deposit the PyPOP atop unmodified graphene sheets, affording a composite material PyPOP@G. The PyPOP demonstrated an appreciable affinity toward CO capture but was found to be largely insulating, hindering its usage in potential electrochemical conversion of CO. However, its composite with graphene was found to be microporous, with maintained affinity toward CO and furthermore demonstrated significant electrochemical activity toward CO reduction (5 mA cm at -1.6 V), not observed in either of its two components separately.

Graphite is a typical electrocatalyst support in alkaline energy conversion and storage devices such as fuel cells, supercapacitores and lithium ion batteries. The electrochemical behaviour of a graphite electrode in 0.5 M NaOH was studied to elucidate its surface structure/electrochemical activity relationship. Graphite voltammograms are characterized by an anodic shoulder AI and a cathodic peak CI in addition to the oxygen reduction reaction plateaus, PI and PII. AI and CI were attributed to oxidation and reduction of some graphite surface function groups, respectively. Rotating ring disk electrode (RRDE) study revealed two different oxygen types assigned as inner and outer oxygen. The inner oxygen was reduced via the more efficient 4-electron pathway. The outer oxygen reduction proceeded with a lower efficient 2-electron pathway. The calculated percentages of the 4-electron pathway were ranged from 70% to 90%. A full mechanism for the graphite surface function groups changes over the studied potential window was suggested through the combination between the voltammetric, FT-IR and Raman results.

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The best learning outcomes are rarely achieved without motivating the learner and in this regard, active teaching and learning methods have been proven useful. Here, we introduce the "learn and innovate" strategy to enhance the students' interest, conceptual understanding, and deep learning under full guiding instructions. Moreover, by this strategy, we encourage the students to conduct an independent research while acquiring high level thinking skills. Designing appropriate instructional strategies and innovative research tasks and media-which leads to collaborative/cooperative learning-enhances the students' interaction with the course materials. The method supports the students to gain self-confidence, motivation and scientific skills to address different research challenges at early stages while enhancing their learning level. In this context, the adopted strategy fosters a first semester master student to deeply understand the new "Leidenfrost Nanochemistry" phenomenon to synthesize Au nanoparticles. Acquiring such knowledge, the student can participate in solving an exploratory research problem and the related experimental challenges. The "learn and innovate" approach has been proven to be a pivotal and novel active teaching strategy to stimulate the active learning of students and the innovative education based Aha! effect.