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An X-ray amorphous material with a CHA-like structure, named embryonic CHA zeolite, has been designed and employed for the synthesis of SSZ-13, which leads to ultra-fast crystallization (1.5–12 h), wide product SiO2/Al2O3 ratio (SAR = 22–100) and high yield (82.8–92.9%). The usage of N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) for the synthesis can be controlled at unprecedentedly low amounts (TMAdaOH/SiO2 = 0.035–0.050). Characterization results reveal that the embryonic zeolite has a small particle size of 10–20 nm, large micro/mesopore volume and abundant double 6-ring units (subunits of the CHA structure). It provides ample active surface and subunits for the formation of the CHA structure and promotes the fast synthesis of SSZ-13 with a wide phase region. The resultant material (SAR = 23.2), after Cu2+ exchange, exhibits superior NH3-SCR activity and extraordinary hydrothermal stability (steaming at 800 °C for 16 h), implying its promising application for NOx removal. In addition, high-silica SSZ-13 shows good catalytic performance for the MTO reaction. It is anticipated that the embryonic zeolite-assisted strategy will benefit the synthesis of more industrially important zeolites. [ABSTRACT FROM AUTHOR]

The targeted synthesis of crystalline microporous silicoaluminophosphate (SAPO) molecular sieves (MSs) with desired topologies is challenging. Conventionally, the trial-and-error approach assisted by computational methods is widely utilized for this exploration. The identification of predicted organic structure-directing agents (OSDAs) by this method is usually based on a neutral aluminophosphate or pure silica framework as the initial structural model, ignoring the host–guest interaction. To some extent, this may affect the prediction result. Herein, we present a novel approach called RSS (Refining, Summarizing, and Searching), which is used for identifying appropriate OSDAs for synthesizing specific SAPO MSs. The RSS approach is mainly based on understanding the structural roles of the alkyl groups of OSDAs and the host–guest interaction elucidated from refinement analysis against experimental diffraction data. By adopting the RSS approach, the OSDAs of a small pore SAPO MS DNL-6 (RHO topology) have been extended from two types reported by us to fourteen additional commercialized ones. DNL-6 has shown promising CO2/N2 gas separation and the unique intermediate heptamethylbenezenium cations have been identified in DNL-6 during the methional-to-olefin (MTO) reaction in our previous work. The universality of this approach manifests the targeted synthesis of another SAPO MS SAPO-42 (LTA topology) by employing cheap commercialized OSDAs. Before our work, this material could only be synthesized using complex and expensive OSDAs in a toxic F− medium. [ABSTRACT FROM AUTHOR]

The zinc cation accommodation in the cavities of the shell layer and the facilitated aromatic formation over the zinc cation modified SAPO-34 with a core–shell like structure introduce extra diffusion limitation for bulky hydrocarbons, which increases the selectivity to ethylene and the ethylene to propylene ratio at the initial stage of the MTO reaction. [ABSTRACT FROM AUTHOR]

Ultra-high onset potential hinders the application of hematite for photoelectrochemical (PEC) water splitting. Herein, a hematite photoanode with an unprecedentedly low onset potential of 0.50 V vs. the reversible hydrogen electrode for PEC water oxidation is reported. The drastically reduced onset potential is mainly ascribed to the passivation of the hematite surface states and the gradient structure made by H2–O2 flame at high temperature. [ABSTRACT FROM AUTHOR]

Chemically converted graphene (CCG) was found to effectively quench the fluorescence emission of Cy3 dye 1 (the intensity is down to 1/38 of 1 alone) in aqueous solution, due to the formation of a CCG-1 hybrid. After the addition of a certain amount of bovine serum albumin (BSA) into the above-mentioned system, about 60 times fluorescence enhancement was observed for the hybrid CCG-1. This was employed to discriminate BSA: the fluorescence intensity was found to be proportional to the BSA added in the concentration range from 0 to 8 × 10 -6 M, and the BSA detection limit was down to 5 × 10 -8 M.

The surface features of semiconductors play very important roles in photocatalytic processes but they are far from being well understood. In this work, we used CdS nanocrystals (NCs) as a model semiconductor photocatalyst to investigate the influence of surface features on photocatalytic activity. The effects of surface modification on the recombination behavior were studied by photoluminescence (PL) spectroscopy. The surface of CdS NCs was modified by tuning the surface S/Cd ratio or by co-loading with Pt and/or PdS co-catalysts. It was found that the surface modifications significantly affect the emission bands at ~540 nm due to shallow traps and ~650 nm assigned to S(2-) vacancies, and consequently the photocatalytic activities. Without co-catalysts loading, the excited carriers are readily transferred to the shallow traps, while they are readily transferred to the co-catalysts upon co-catalysts loading. These results demonstrate that the surface features are crucial to photocatalytic activity of the CdS NCs. The surface modification is helpful for the excited carriers to transfer to either the shallow trap states or co-catalysts, resulting in higher quantum efficiency of photocatalytic H(2) production.