Highly efficient and stable electrocatalysts, particularly those that are capable of multifunctionality in the same electrolyte, are in high demand for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). In this work, highly monodisperse CoP and Co P nanocrystals (NCs) are synthesized using a robust solution-phase method. The highly exposed (211) crystal plane and abundant surface phosphide atoms make the CoP NCs efficient catalysts toward ORR and HER, while metal-rich Co P NCs show higher OER performance owing to easier formation of plentiful Co P@COOH heterojunctions. Density functional theory calculation results indicate that the desorption of OH* from cobalt sites is the rate-limiting step for both CoP and Co P in ORR and that the high content of phosphide can lower the reaction barrier. A water electrolyzer constructed with a CoP NC cathode and a Co P NC anode can achieve a current density of 10 mA cm at 1.56 V, comparable even to the noble metal-based Pt/C and RuO /C pair. Furthermore, the CoP NCs are employed as an air cathode in a primary zinc-air battery, exhibiting a high power density of 62 mW cm and good stability.

In the colloidal synthesis of inorganic perovskite materials, cesium oleate (CsOL) is the most commonly used Cs precursor. Yet, despite its ubiquitous use in literature, CsOL has been observed to be insoluble at room temperature and leads to surprisingly inconsistent results in CsPbX3 nanocrystal synthesis, depending on the Cs salt from which the precursor is derived. We show that under the conditions used in most reports, the amount of oleic acid (OA) added, while stoichiometrically sufficient, still leads to incomplete conversion of the Cs salts to CsOL. This results in a mixture of Cs sources being present during the reaction, causing decreased homogeneity and reproducibility. When a 1:5 Cs:OA ratio is used, complete conversion is readily obtained, even under mild conditions, resulting in a precursor solution that is soluble at room temperature and yields identical synthetic results, regardless of the initial Cs source. Furthermore, 1H nuclear magnetic resonance (NMR) of solutions prepared using varying Cs:OA ratios shows that the maximum ratio of Cs:OA obtainable in solution is 1:5, with any excess Cs present in the precipitate. We believe the use of a soluble, fully converted CsOL reagent will improve reproducibility for Cs-based perovskite synthesis and directly benefit synthetic methods based on microfluidics.

A nickel-catalyzed stereoconvergent method for the enantioselective Suzuki arylation of racemic α-chloroamides has been developed. This process represents the first example of an asymmetric arylation of an α-haloamide, of an enantioselective arylation of an α-chlorocarbonyl compound, and of an asymmetric Suzuki reaction with an activated alkyl electrophile or an arylboron reagent. The method is also applicable to the corresponding enantioselective cross-coupling of α-bromoamides. The coupling products can be transformed without racemization into useful enantioenriched α-arylcarboxylic acids and primary alcohols. An unprecedented (and modest) kinetic resolution of the α-chloroamide has been observed; a mechanistic study indicates that the selectivity likely reflects the discrimination by the chiral catalyst of the two enantiomeric α-chloroamides in an irreversible oxidative-addition process.Enantioenriched α-arylcarboxylic acids that bear a tertiary α stereocenter, including arylpropionic acids such as naproxen, serve as important therapeutics as well as useful intermediates in organic synthesis. 1,2 Although the cross-coupling of enolates with aryl electrophiles has not yet proved to be a viable route to the generation of such compounds, 3 a few reports have described the umpolung approach, i.e., the coupling of an α-halocarbonyl compound with an aryl nucleophile. Whereas organozinc, 4 organosilicon, 5 and organomagnesium 6 reagents have been employed in such processes (with α-bromoketones and α-bromoesters), organoboron compounds have not. 7,8,9,10 In this report, we establish that a chiral nickel catalyst can achieve asymmetric cross-couplings of arylboron reagents with racemic α-haloamides to generate tertiary α-arylcarbonyl compounds in good ee (eq 1). After surveying an array of reaction parameters, we determined that NiBr 2 · diglyme/1 can catalyze the cross-coupling of an α-chlorobutyramide with Ph-(9-BBN) in good ee and yield (entry 1 of Table 1). The cross-coupling illustrated in entry 1 is noteworthy in part because there are no previous examples of enantioselective arylations of α-haloamides, of asymmetric Suzuki reactions of activated alkyl electrophiles or arylboron 11 reagents, or of enantioselective arylations of α-chlorocarbonyl compounds. 12 Both NiBr 2 · diglyme and ligand 1 are commercially available.In the absence of NiBr 2 · diglyme, essentially no carbon-carbon bond formation is observed (entry 2 of Table 1), and, in the absence of ligand 1, the cross-coupling proceeds very slowly (entry 3). If i-BuOH is omitted, the reaction is also sluggish (entry 4), and, if water is used in place of i-BuOH, the product is generated with good enantioselectivity, but modest yield (entry 5). The cross-coupling occurs with somewhat lower ee if ligand 2 is employed rather than ligand 1 (entry 6) or if it is conducted at room temperature (entry 7). Use of less catalyst leads to a slightly diminished yield (entry 8). A variety of other α-chloroamides (both tertiary and secondary), as well as an α-chlor...

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Ohne Aktivatoren: Eine katalytische asymmetrische Kreuzkupplung von Arylzinkreagentien mit α‐Bromketonen wurde entwickelt (siehe Schema). Die stereokonvergente Kohlenstoff‐Kohlenstoff‐Verknüpfung verläuft unter ungewöhnlich milden Bedingungen und eignet sich so zum Aufbau potenziell labiler tertiärer Stereozentren.