The design of solid electrolytes with a wide electrochemical stability window and high Li-ion conductivity is a prerequisite for the realization of all solid-state Li batteries, which promises to enable extraordinary levels of safety for the battery system and may potentially revolutionize the energy storage field. Among all the promising inorganic solid electrolytes, Li4MS4 (M = Si, Ge, and Sn) with a crystal structure of Pnma symmetry have recently been recommended due to their good air stability and ionic conductivity. Here, we employ ab initio simulations to conduct a systematic investigation of the electrochemical stability and Li conductivity of Li4MS4 compounds. Our computation results reveal that the edge-sharing and face-sharing characteristics of LiS4 and LiS6 polyhedra not only facilitate the formation of a percolating Li diffusion network but would severely destabilize the crystal structure as well, thus resulting in a rather narrow electrochemical window. Although the stronger M–S bonds manifested in Li4SiS4 can benefit the overall stability, unfortunately, it also contributes to a more rugged energy landscape that inhibits Li diffusion. Li4SnS4 with a less densely packed lattice exhibits a substantially lower energy for Li ions to be accommodated at interstitial sites, which is a trigger for high Li conductivity in the bulk material, reaching 11 mS/cm at room temperature. The fast Li diffusion occurs through the concerted migration of multiple Li ions at lattice and interstitial sites. These findings open up new possibilities for the rational design of Li4MS4 (M = Si, Ge, and Sn) solid electrolytes for next-generation Li batteries.

diffusion length, and high light absorption coefficient. [7][8][9] These research efforts have witnessed the steady promotion of their power conversion efficiencies (PCEs) from 3.8% to 25.5%. [10] Nonetheless, the instability of the organic components against light, humidity, and heat remains the most pernicious problem jeopardizing their commercial applications. [11][12][13] It is therefore recommended to replace the organic components with inorganic cations, one example being α-CsPbI 2 Br, [14][15][16][17][18][19][20] which demonstrates outstanding optoelectronic properties. While the stability is being improved, the PCE (17.46%) [21] of α-phase CsPbI 2 Br is still far below the Shockley-Queisser (SQ) limit (24.75%) [22] and thus inferior to its hybrid organic-inorganic counterparts.Recently, it was observed that surface defect passivation can effectively enhance the PCE of the CsPbI 2 Br PSC. [23][24][25][26][27][28][29] Annihilation of surface I and Br vacancies via the incorporation of external anions was proposed to be the root cause of the improved performance, [30] but the underlying mechanism is still under debate. Some researchers suggested that the interactions with external anions could suppress the migration of surface ions in CsPbI 2 Br, thus alleviating the hysteresis effect, [31] while others ascribed the improvement to the reduction of parasitic nonradiative charge-carrier recombination centers formed by surface point defects. [32] One such point defect in CsPbI 2 Br is the Pb Br (Pb replacing Br) antisite. It has been shown in the literature that Pb Br is occasionally formed when a Br vacancy is generated in the lattice with an additional Pb captured at this vacant site. [33][34][35][36] This defect can induce detrimental deep-level defect states in the bandgap. [23,24,28,[37][38][39][40] Several reports have indicated that alkali metal halide can electronically passivate the Pb Br defect at the surface and prolong the durability of the solar cells. [37][38][39][40] In the passivation process, the ions are adsorbed at the surface vacant sites with sufficiently low kinetic barriers, which is similar to ion batteries, but different in that the adsorption process is irreversible while ionic intercalation in batteries is reversible. [41] Despite the abundance of experimental evidence, the atomistic understanding of the passivation mechanisms has not yet been achieved.Considering the fact that the substantive key to passivation lies in the incorporation of external anions, we conduct a Despite the excellent optoelectronic properties, organic-inorganic hybrid perovskite solar cells (PSCs) still present significant challenges in terms of ambient stability. CsPbI 2 Br, a member of all-inorganic perovskites, may respond to this challenge because of its inherent high stability against light, moisture, and heat, and therefore has gained tremendous attraction recently. However, the practical application of CsPbI 2 Br is still impeded by the notorious phenomenon of photoinduced halide segregation. Herein, by...

Al coating on U surfaces is one of the methods to protect U against environmental corrosion. The behaviors of hydrogen and oxygen impurities near the Al/α-U interface have been studied in the density functional theory framework. It turns out that U vacancies tend to segregate to the interface with segregation energies of around 0.5-0.8 eV. The segregated U vacancy can act as a sink for H and O impurities, which is saturated when filled with 8 H or 6 O atoms, respectively. Moreover, the O impurities tend to stay in the Al layer while the H impurities prefer to diffuse into the U lattice, suggesting that the Al coating can play a significant role against oxidation but not against hydrogenation of U.

Plant bioactive metabolites such as flavonoids are usually present in glycosylated forms by the attachment of various sugar groups. In this study, a catalytically flexible and reversible glycosyltransferase (HtUGT72AS1) was cloned and characterized from Helleborus thibetanus. HtUGT72AS1 could directly accept six sugar donors (UDP-glucose/-arabinose/-galactose/-xylose/-Nacetylglucosamine/-rhamnose) to catalyze the 3-OH glycosylation of flavonols. It also catalyzed the 4′ and 7-OH glycosylation of other types of flavonoids, which lacked the 3-OH group. Additionally, the HtUGT72AS1-catalyzed reaction was highly reversible when using 2-chloro-4-nitrophenyl glycosides as substrates, which could be used for one-pot or coupled production of bioactive glycosides. It is the first reported UGT for the synthesis of arabinosides and galactosides using a transglycosylation platform. Based on structural modeling and mutagenetic analysis, the mutation of Tyr377 to Ara enhanced the catalytic efficiency of HtUGT72AS1 toward UDP-N-acetylglucosamine, and the V146S mutant gained an improvement in the regioselectivity toward 7-OH of flavonoids.

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