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An electrochemical nitrogen reduction reaction (ENRR) is considered a promising alternative for the traditional Haber-Bosch process. In this study, we present a method for improving the ENRR by controlling the wettability of the catalyst surface, suppressing the hydrogen evolution reaction (HER) while facilitating N

The Cd4S6+ and Cd2S2+ clusters in the sodalite cavities were synthesized by reaction of the fully Cd2+-exchanged zeolite Y (Si/Al = 1.56) and 0.1 M Na2S(aq) solution at 294 K for 2 days. The single-crystal structure was determined at 100(1) K by synchrotron X-ray diffraction techniques in the cubic space group Fd $$\overline{3}$$ m. The structure was refined using all intensities to the final error index R1/wR2 = 0.048/0.156 (for Fo > 4σ(Fo)). Approximately 13 Cd2+ and 53 Na+ ions per unit cell were found at two and four crystallographically distinct positions, respectively: two site-Iʹ positions (in the sodalite cavities opposite double 6-rings (D6Rs)) are occupied by 5 and 7.5 Cd2+ ions, respectively, per unit cell. The 0.5 Cd2+ ions per unit cell are at site IIʹ in the sodalite cavity. The 2 Na+ ion is located at the center of the D6R (site I). The 15.5 Na+ ions per unit cell are located at site Iʹ. Site-II position is occupied by 31.5 Na+ ions per unit cell. The remaining 4 Na+ ions per unit cell are located at sites IIIʹ near triple 4-rings in the supercage. Finally, 0.5 and 1.5 S2− ions per unit cell, associated with Cd2+ ions, were found at the center of sodalite cavity and opposite 6-ring in the sodalite cavity, respectively. The 1 S2− ion at the center of the sodalite cavity is coordinated to 4 Cd2+ ions at site Iʹ to give a centered-tetrahedral cationic cluster, Cd4S6+, and the other S2− ion opposite 6-ring in the sodalite cavity bridges between two Cd2+ ions at site Iʹ to give a cationic cluster with a bent arrangement, Cd2S2+, in 6.3% and 18.8% of the sodalite cavities of zeolite Y (Si/Al = 1.56), respectively.

The extraframework sodium sulfide cationic cluster, Na4S2+, has been introduced into zeolite Y (FAU, Si/Al = 1.56). A single crystal of |Na73(Na4S2+)1.0|[Si117Al75O384]-FAU was prepared by allowing aqueous 0.1 M Na2S solution to flow past a |Na75|[Si117Al75O384]-FAU crystal, and followed by vacuum dehydration at 723 K. Its structure was determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd $$\overline{3}$$ m. The structure was refined using all intensities to the final error index R1/wR2 = 0.044/0.125. About 77 Na+ ions per unit cell are found at the crystallographically distinct positions, six. One Na+ ion per unit cell is at the center of double 6-ring. Two site-I′ positions are occupied by 26.5 and 4 Na+ ions, respectively, per unit cell. Thirty-two Na+ ions per unit cell are found at site II, in the supercage opposite single 6-rings. The remaining 4.5 and 9 Na+ ions per unit cell occupy two sites III′ near triple 4-rings in the supercage. Finally, one sulfide ion per unit cell, associated with Na+ ions, is found at the center of sodalite cavity. The 4 Na+ ions at site I′ coordinate to a sulfide ion at the center of sodalite cavity to give tetrahedral cationic cluster, Na4S2+. In |Na73(Na4S2+)1.0|[Si117Al75O384]-FAU, tetrahedral Na4S2+ ions center about 12.5% of the sodalite cavities.

To study the Sr2+-ion selectivity of zeolite Y (Si/Al = 1.56) in binary solution with different Sr2+ and K+ concentration during exchange, two single-crystals of fully dehydrated, Sr2+- and K+-exchanged zeolites Y were prepared by the flow method using a mixed ion-exchange solution whose Sr(NO3)2:KNO3 mol ratios were 1:1 (crystal 1) and 1:100 (crystal 2), respectively, with a total concentration of 0.05 M, followed by vacuum dehydration at 723 K. Their crystal structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $$ Fd\bar{3}m $$, respectively, and were refined to the final error indices R1/wR2 = 0.0429/0.1437 and 0.0356/0.1239 for crystals 1 and 2, respectively. In the structure of |Sr28K19|[Si117Al75O384]-FAU (crystal 1), 28 Sr2+ ions per unit cell occupy four different crystallographically distinct sites; 15, 2, 2, and 9 are at sites I, I′, II′, and II, respectively, whereas, the K+ ions occupy only one site: 19 are at site II. In the structure of |Sr17K41|[Si117Al75O384]-FAU (crystal 2), 17 Sr2+ ions per unit cell occupy three equipoints; 10.5, 2, and 4.5 are at sites I, I′, and II, respectively. The residual 41 K+ ions per unit cell are found at four different sites; 8, 24, 3, and 6 are at sites I′, II, III′a, and III′b, respectively. The degrees of ion exchange are 74.7 and 45.3% for crystals 1 and 2, respectively. This result shows that the degree of Sr2+ exchange decreased sharply by decreasing the initial Sr2+ concentration and increasing the initial K+ concentration in the given ion-exchange solution.

Three single-crystals of fully dehydrated and partially Sr2+-exchanged zeolites Y (Si/Al = 1.56) were prepared by the flow method using mixed ion-exchange solutions. The Sr(NO3)2:NaNO3 molar ratios of the ion exchange solution were 1:100 (crystal 1), 1:250 (crystal 2), and 1:500 (crystal 3) with a total concentration of 0.05 M. The single-crystals were then vacuum dehydrated at 723 K and 1 × 10−4 Pa for 2 days. The structures of the crystals were determined by single-crystal synchrotron X-ray diffraction technique in the cubic space group $$Fd\bar {3}m$$ , at 100(1) K, and were then refined to the final error indices of R1/wR2 = 0.044/0.167, 0.051/0.175, and 0.069/0.219 for crystals 1, 2, and 3, respectively. The unit-cell formulas of crystals 1, 2, and 3 were |Sr17Na41|[Si117Al75O384]-FAU, |Sr13Na49|[Si117Al75O384]-FAU, and |Sr9Na57|[Si117Al75O384]-FAU, respectively. In all three crystals, the Sr2+ ions preferred to occupy site I in the D6Rs, with the remainder occupying site II. The Sr2+ ions are also located at site I′ in crystal 1. On the other hand, the Na+ ions are located at sites I′, II, and III′ in all crystals. With increasing the molar concentration of Na+ in the given exchange solution, the occupancies of the Sr2+ ions at sites I, I′, and II decreased, whereas the occupancies of the Na+ ions at sites I′, II, and III′ increased.

Four single crystals of fully dehydrated and partially Zn2+-exchanged zeolites Y (Si/Al = 1.56) were prepared by the static ion-exchange method using a mixed ion-exchange solution in which Zn(NO3)2:NaCl mole ratios were 1:1 (crystal 1), 1:25 (crystal 2), 1:50 (crystal 3), and 1:100 (crystal 4), respectively, with a total concentration of 0.05 M, and followed by vacuum dehydration at 673 K. Their single-crystal structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd $$\bar {3}$$ m and refined to the final error indices R1/wR2 = 0.0459/0.1454, 0.0449/0.1283, 0.0427/0.1284, and 0.0486/0.1680, respectively. Their unit-cell formulas are |Zn25Na25|[Si117Al75O384]-FAU (crystal 1), |Zn19.5Na36|[Si117Al75O384]-FAU (crystal 2), |Zn19.5Na36|[Si117Al75O384]-FAU (crystal 3), and |Zn7Na61|[Si117Al75O384]-FAU (crystal 4), respectively. The degree of Zn2+ exchange decreases from 67 to 19% as the initial concentration of Zn2+ decrease and the initial concentration of Na+ increases in given ion-exchange solutions.

Centered-tetrahedral cationic clusters are frequently found in the sodalite cavities of zeolites and in the cavities of analogues of the mineral sodalite. Examples are Mn4S6+, Fe4Te6+, Zn4Se6+, Cd4S6+, Cu4Cl7+, Na4Cl3+, Na4I3+, Na54+, In57+, Ga57+, and Sn512+.

Synthesis of morphologically well-defined crystals of metalloporphyrin by direct crystallization based on conventional anti-solvent crystallization method without using any additives has been rarely reported. Herein, we demonstrate an unconventional and additive-free synthetic method named reverse anti-solvent crystallization method to achieve well-defined zinc-porphyrin cube crystals by reversing the order of the addition of solvents. The extended first solvation shell effect mechanism is therefore suggested to support the synthetic process by providing a novel kinetic route for reaching the local supersaturation environment depending on the order of addition of solvents, which turned out to be critical to achieve clean cube morphology of the crystal. We believe that our work not only extends fundamental knowledge about the kinetic process in binary solvent systems, but also enables great opportunities for shape-directing crystallization of various organic and organometallic compounds.