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Conventional strategies for highly efficient and selective CO2 photoreduction focus on the design of catalysts and cocatalysts. In this study, we discover that hydrogen bond network breakdown in reaction system can suppress H2 evolution, thereby improving CO2 photoreduction performance. Photosensitive poly(ionic liquid)s are designed as photocatalysts owing to their strong hydrogen bonding with solvents. The hydrogen bond strength is tuned by solvent composition, thereby effectively regulating H2 evolution (from 0 to 12.6 mmol g−1 h−1). No H2 is detected after hydrogen bond network breakdown with trichloromethane or tetrachloromethane as additives. CO production rate and selectivity increase to 35.4 mmol g−1 h−1 and 98.9 % with trichloromethane, compared with 0.6 mmol g−1 h−1 and 26.2 %, respectively, without trichloromethane. Raman spectroscopy and theoretical calculations confirm that trichloromethane broke the systemic hydrogen bond network and subsequently suppressed H2 evolution. This hydrogen bond network breakdown strategy may be extended to other catalytic reactions involving H2 evolution. [ABSTRACT FROM AUTHOR]

CO2 cycloaddition with epoxides is a key catalytic procedure for CO2 utilization. Several metal-based catalysts with cocatalysts are developed for photo-driven CO2 cycloaddition, while facing difficulties in product purification and continuous reaction. Here, poly(ionic liquid)s are proposed as metal-free catalysts for photo-driven CO2 cycloaddition without cocatalysts. A series of poly(ionic liquid)s with donor-acceptor segments are fabricated and their photo-driven catalytic performance (conversion rate of 83.5% for glycidyl phenyl ether) outstrips (≈4.9 times) their thermal-driven catalytic performance (17.2%) at the same temperature. Mechanism studies confirm that photo-induced charge separation is promoted by the donor-acceptor segments and can accelerate the CO2 cycloaddition reaction. This work paves the way for the further use of poly(ionic liquid)s as catalysts in photo-driven CO2 cycloaddition. [ABSTRACT FROM AUTHOR]

Due to the limited resources and high cost of noble metals, boosting their catalytic activities is highly desired in the current catalysis industry. Here, we report a synergetic catalyst, combining Pd2+ and Pd0 species in a nitrogen‐doped porous carbons (NPC), which shows boosted catalytic activities in hydrogenation reactions of organic nitro compounds (nitrobenzene, 4‐nitrophenol, 1‐nitronaphthalene and 1‐nitropropane) under near ambient conditions. This synergetic catalyst NPC‐[Pd] was synthesized by partial reduction of a palladium‐loaded NPC. The catalytic activities and selectivity of NPC‐[Pd] for hydrogenation were enhanced significantly compared with those of NPC‐Pd2+ or NPC‐Pd0 nanoparticles. Theoretical calculations show that H2 preferentially dissociates on Pd nanoparticles, and then organic molecules (nitrobenzene) can be captured and react with the dissociated H atom on Pd2+ sites. Similar reaction procedure also occur on Pt or Rh. Hydrogenation of different aromatic compounds with different functional groups (naphthalene, 4‐nitrochlorobenzene, benzaldehyde and acetophenone) confirmed the broad excellent catalytic activity of this synergistic catalyst. [ABSTRACT FROM AUTHOR]

AngewandteCover Picture Chengcheng Liu, Weiqiao Deng et al. Hydrogen- Bond- Network Breakdown Boosts Selective CO2 Photoreduction by Suppressing H2 Evolution ACIEFS 63 ( 21) ( 2024) · ISSN 1433– 7851 · Vol. 63 · No. 21 Angewandte Chemie International Edition 2024, No. 21 A Journal of the German Chemical Society Chemie International Edition www. angewandte. org 2024– 63/ 21 [Extracted from the article]

A recent research article published in Angewandte Chemie discusses the breakdown of the hydrogen bond network in the CO2 photoreduction system, which can suppress the evolution of H2 and increase the production of CO. The study by Chengcheng Liu, Weiqiao Deng, and others focuses on the use of photosensitive poly(ionic liquid)s as photocatalysts, which have strong hydrogen bonding with solvents. By disrupting the hydrogen bond network with solvent additives, the researchers were able to effectively suppress H2 evolution in photocatalytic CO2 reduction. Another research article in the journal discusses the use of metal-organic frameworks to achieve photocatalytic CO2 reduction to syngas. [Extracted from the article]

NH3 oxidation mechanism and its inhibition effect on the selective catalytic reduction of NO x by NH3 (NH3-SCR) reaction over two series of Cu/SAPO-34 catalysts were studied. It was found that the different NO conversions were induced by the diverse NH3 oxidation degree. X-ray diffraction, scanning electron microscopy, H2 temperature-programmed reduction (H2-TPR), and CO diffuse reflectance infrared Fourier transform spectroscopy (CO-DRIFTS) analyses were conducted to estimate the Cu species distribution. The TPR results showed that the CuO species was dominant in impregnated Cu/SAPO-34 samples, and the ion-exchanged Cu/SAPO-34 samples contained more isolated Cu2+ species. Furthermore, H2-TPR, electron paramagnetic resonance, and CO-DRIFTS analyses were utilized to quantify the CuO, Cu2+, and Cu+ species. The results together with the kinetic results revealed the CuO is the active site for NH3 oxidation, and the NH3 oxidation over Cu/SAPO-34 sample consists two steps: (a) NO production; (b) further NO consumption by adsorbed NH3 species on Cu2+ sites. Finally, the inhibition of NH3 oxidation on NH3-SCR activity was explained and the NO conversion at high temperature was related to the Cu2+/CuO ratio in Cu/SAPO-34 sample. [ABSTRACT FROM AUTHOR]

Epoxy/SiO2 nanocomposite materials were prepared by cationic photopolymerization and sol-gel process using a novel epoxy oligomer (EP-Si(OC2H5)3) prepared by 3-isocyanatopropyltriethoxysilane (IPTS)-grafted bisphenol A epoxy resin and tetraethyl orthosilicate as inorganic precursor. The chemical structures of EP-Si(OC2H5)3 were characterized by Fourier transformed infrared spectroscopy. Transmission electron microscopy showed that the in situ generated nano-SiO2 dispersed uniformly in the EP matrix, and its average diameter is around 40 nm. The relationship between nanocomposite materials' thermal/mechanical properties and nano-SiO2 introduced were studied by thermogravimetric analysis, dynamic mechanical analysis, and impact strength test. The results showed that the nanocomposite materials' thermal and mechanical properties improved a lot with increase of the SiO2 content. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The title compound, C(9)H(10)N(2)O(3)·2H(2)O, crystallizes with two organic mol-ecules and four water mol-ecules in the asymmetric unit. Both organic mol-ecules adopt a trans conformation with respect to the C=N bond and are close to planar [dihedral angles between the side chain and the aromatic ring = 9.34 (8) and 4.96 (8)°]. In the crystal, the components are linked into three-dimensional network by N-H⋯O and O-H⋯O hydrogen bonds.

The title mol-ecule, C(12)H(16)N(2)O(5), adopts a trans configuration with respect to the C=N bond. In the crystal, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains in [001], and weak inter-molecular C-H⋯O inter-actions further link the chains into corrugated layers parallel to the bc plane.

The asymmetric unit of the title compound, C(11)H(11)N(3)O(2)·0.25H(2)O, contains two independent organic mol-ecules and a water mol-ecule, which lies on a twofold rotation axis. The side chains of the two mol-ecules have slightly different orientations, the C=N-N-C torsion angle being -163.03 (15)° in one and -177.52 (14)° in the other, with each adopting a trans configuration with respect to the C=N bond. In the crystal, mol-ecules are linked into chains extending along b by N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds and in addition, four inter-molecular C-H⋯π inter-actions are present.

In the title mol-ecule, C(10)H(12)N(2)O(2), the acetohydrazide group is almost planar [within 0.0306 (12) Å] and forms a dihedral angle of 12.15 (14)° with the benzene ring. The meth-oxy group deviates from the attached benzene ring with a C-O-C-C torsion angle of 4.2 (4)°·The mol-ecule adopts a trans configuration with respect to the C=N bond. In the crystal, mol-ecules are linked into centrosymmetric dimers by pairs of N-H⋯O hydrogen bonds and intermolecular C-H⋯O interactions further stabilize the structure.

In the title mol-ecule, C(7)H(8)N(2)O(2), the acetohydrazide group is planar within 0.014 (2) Å and forms a dihedral angle of 5.35 (8)° with the furan ring. The mol-ecule adopts a trans configuration with respect to the C=N bond. In the crystal, molecules are linked into a chain along the a axis by N-H⋯O hydrogen bonds.

The title compound, C(11)H(15)N(3)O, crystallizes with two independent mol-ecules per asymmetric unit which differ slightly in their side-chain orientations: the C=N-N-C torsion angle is -176.2 (3)° in one of the mol-ecules and -179.83 (3)° in the other. Each independent mol-ecule adopts a trans configuration with respect to the C=N bond. The two independent mol-ecules are related by a pseudo-inversion center and they exist as a N-H⋯O hydrogen-bonded dimer. The dimers are linked into zigzag chains along [100] by C-H⋯O hydrogen bonds.

In the title compound, C(9)H(10)N(2)O(2)·H(2)O, the mol-ecular skeleton of the acetohydrazide mol-ecule is nearly planar [within 0.014 (1) Å]. The mol-ecule adopts a trans configuration with respect to the C=N bond, while the side chain is slightly twisted away from the attached ring, forming a dihedral angle of 9.975 (8)°. The crystal packing exhibits a three-dimensional network composed from alternating acetohydrazide mol-ecules and uncoordinated water mol-ecules, which inter-act via N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds. A C-H⋯π inter-action is also present.

In the title mol-ecule, C(11)H(14)N(2)O(3), the acetohydrazide group is planar 0.084 (1) Å and forms a dihedral angle of 19.7 (1)° with the benzene ring. One of the meth-oxy groups is coplanar with the attached benzene ring within 0.052 (3) Å, whereas the other is slightly twisted [C-O-C-C = 6.3 (3)°]. The mol-ecule adopts a trans configuration with respect to the C=N bond. In the crystal, the mol-ecules are linked into chains along the a axis by N-H⋯O hydrogen bonds and the chains are cross-linked into a three-dimensional network by C-H⋯O hydrogen bonds.

In the title mol-ecule, C(10)H(12)N(2)O(2), the acetohydrazide group is planar within 0.012 (1) Å and forms a dihedral angle of 5.25 (8)° with the benzene ring. The meth-oxy group is coplanar with the attached benzene ring [C-O-C-C = 0.1 (2)°]. The mol-ecule adopts a trans configuration with respect to the C=N double bond. In the crystal, mol-ecules are linked into centrosymmetric dimers by N-H⋯O hydrogen bonds and these dimers are linked into a ribbon-like structure along [110] by C-H⋯O hydrogen bonds. In addition, an inter-molecular C-H⋯π inter-action is observed.

The mol-ecule of the title compound, C(10)H(12)N(2)O(4), adopts a trans configuration with respect to the C=N bond. The dihedral angle between the benzene ring and the methyl hydrazinecarboxyl-ate plane is 3.01 (6)°. An intra-molecular O-H⋯N hydrogen bond is observed. In the crystal, mol-ecules are linked into a two-dimensional network parallel to (10) by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds.

In the title compound, C(8)H(10)N(2)O(3), the hydrazinecarboxyl-ate group is twisted from the furan ring by 6.98 (17)°. In the crystal, the mol-ecules are linked into one-dimensional chains running along the c axis by N-H⋯O hydrogen bonds.

The title compound, C(10)H(12)N(2)O(4), adopts a trans configuration with respect to the C=N bond. The hydrazinecarboxyl-ate group is twisted from the benzene ring by 6.62 (5)° and an intramolecular O-H⋯O hydrogen bond occurs. In the crystal structure, mol-ecules are linked into a two-dimensional network parallel to (100) by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds. In addition, weak C-H⋯π inter-actions are observed.