The development of highly active and stable bifunctional noble-metal-based electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is a crucial goal for clean and renewable energy, which still remains challenging. Herein, we report an efficient and stable catalyst comprising a Co single atom incorporated in an RuO 2 sphere for HER and OER, in which the Co single atom in the RuO 2 sphere was confirmed by XAS, AC-STEM, and DFT. This tailoring strategy uses a Co single atom to modify the electronic structures of the surrounding Ru atoms and thereby remarkably elevates the electrocatalytic activities. The catalyst requires ultralow overpotentials, 45 mV for HER and 200 mV for OER, to deliver a current density of 10 mA cm À 2 . The theoretical calculations reveal that the energy barriers for HER and OER are lowered after incorporation of a cobalt single atom.

Researchers working in the field of photovoltaic are exploring novel materials for the efficient solar energy conversion. The prime objective of the discovery of every novel photovoltaic material is to achieve more energy yield with easy fabrication process and less production cost features. Perovskite solar cells (PSCs) delivering the highest efficiency in the passing years with different stoichiometry and fabrication modification have made this technology a potent candidate for future energy conversion materials. Till now, many studies have shown that the quality of active layer morphology, to a great extent, determines the performance of PSCs. The current and potential techniques of solvent engineering for good active layer morphology are mainly debated using primary solvent, co-solvent (Lewis acid-base adduct approach) and solvent additives. In this review, the dynamics of numerously reported solvents on the morphological characteristics of PSCs active layer are discussed in detail. The intention is to get a clear understanding of solvent engineering induced modifications on active layer morphology in PSC devices via different crystallization routes. At last, an attempt is made to draw a framework based on different solvent coordination properties to make it easy for screening the potent solvent contender for desired PSCs precursor for a better and feasible device.

Recently, mixed-cation perovskites have been extensively used for high-performance solar cells. Nevertheless, the mixed-cation perovskite based on formamidinium methylammonium lead tri-iodide (FA x MA1–x PbI3) fabricated through the existing methods often suffers from phase stability and trap density. Herein, we demonstrate a facile intermediate engineering approach to improve the quality of the mixed-cation perovskite based on FA x MA1–x PbI3. Varying concentrations of methylammonium chloride (MACl) are used to treat the FA–MA–PbI3-solvent intermediate. It is noted that MACl has a strong impact on the crystallization kinetics and charge carrier dynamics as well as the defect density of the obtained perovskite. The mixed-cation perovskite treated with 20 mg mL–1 MACl yields a large grain size, highly uniform morphology, and better crystalline stability. Subsequently, the device with an acquired high-quality mixed-cation perovskite shows a high efficiency of 20.40%, which is obviously higher than that obtained from the traditional nontreated method. Moreover, the device prepared through the developed method could retain over 85% of the initial efficiency after 860 h at room temperature.

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A new facile fused tetraphenylethylene–triphenylamine hole transporting material has been developed, which shows obviously higher performance than the non-fused counterpart in perovskite solar cells.