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The optimal ratio of reaction solutions resulted in excellent performance and product selectivity of CuO/g-C3N4 composites in the photocatalytic CO2 reduction reaction. A pH-dependent chemical exchange saturation transfer (CEST) imaging nuclear magnetic resonance (NMR) method was used to confirm that CuO modification improves the adsorption capacity of CO2. [ABSTRACT FROM AUTHOR]

The photocatalytic production of hydrogen via single-atom catalysts (SACs), in which photoactive metal species are isolated as single atoms on supports, has received increasing interest for the ecologically friendly and sustainable production of hydrogen due to the high catalytic activity, selectivity, stability, and complete utilization of active components in these catalysts. However, a truly facile means of fabricating SACs without the aggregation of the active atoms remains poorly developed. The present work addresses this issue by proposing the use of a novel photochemical reaction conducted in a frozen precursor solution to prepare SACs with active Pd atoms stabilized on graphene carbon nitride (g-C3N4) supports. The single Pd atoms are demonstrated to be fully isolated on the g-C3N4 supports, and the optimal Pd–C3N4 SAC with 0.3 wt% Pd (the ICP result is 0.2855 wt%) is shown to provide a much higher photocatalytic hydrogen production performance (8.736 mmol g−1 h−1) than the non-frozen control group fabricated with an equivalent liquid precursor. Furthermore, computational methods are applied to explain how the proposed photochemical process stabilizes single-atom active sites and the chemical mechanisms responsible for the excellent photocatalytic hydrogen production performance of the SAC. These results demonstrate that the proposed fabrication method can be universally applied for the preparation of SACs. [ABSTRACT FROM AUTHOR]

This work reports an atomic-scale carbon layer configuration tuning strategy induced by a boron dopant. Through regulating the doping level of boron, it was found that the boron dopant not only favors carbon layer growth by strengthening the metallic state of the Ni core, but also enhances the abundance of pyrrolic N species and graphitization degree of carbon by tailoring the carbon/nitrogen atom configuration, thereby contributing to more active pyrrolic N/carbon sites and accelerated interface reaction dynamics. Consequently, the developed Ni@B,N-C catalyst achieves remarkable electrochemical H2O2 production performances with a high selectivity of 95.5% and a yield of 795 mmol g−1 h−1. In comparison with previous reports in which the boron dopant mainly acts as an electronic structure regulator, this study reveals the tuning effect of boron dopants on the atomic-scale carbon layer configuration, opening up a new avenue for the development of advanced catalysts. [ABSTRACT FROM AUTHOR]

The relationship between the structural characteristics and photocatalytic reaction mechanisms of graphitic carbon nitride (g-C3N4) still remains unclarified at the molecular level, which severely hinders the further development of this field. The present study addresses this issue by employing an innovative strategy to investigate the relationship between the H-containing structures of g-C3N4 and its water splitting properties. The exchangeable and unexchangeable protons of the H-containing groups of g-C3N4 were differentiated by selective deuteration, providing a way to distinguish the hydrophilic and relatively non-hydrophilic H-containing groups of g-C3N4. A combination of advanced solid-state NMR approaches reveals that amino group defects (CN2(NHx)) on the C–N skeleton of the photocatalyst likely serve as hydrophilic active sites for facilitating the photocatalytic hydrogen evolution reaction. Accordingly, the newly synthesized g-C3N4 sample having a high concentration of CN2(NHx) by design demonstrates an enhanced H2 yield by a factor of 17 compared to that of pure g-C3N4. [ABSTRACT FROM AUTHOR]

A supramolecular platform prototype for implementing resettable encoding functions was designed, which could be configured into a series of encoders, from 4-to-2 to 7-to-3, and even 14-to-4 ECs. [ABSTRACT FROM AUTHOR]

Solid forms play a central role in modulating and optimizing the physicochemical properties of drugs, among which crystalline inclusion complexes (ICs) represent an emerging subcategory. In this study, we confirmed the inclusion of linear polymer polytetrahydrofuran (PTHF) into carbamazepine (CBZ) Form II, an extensively studied crystal structure with unique channel voids in its unsolvated form. According to solid-state NMR, PTHF chains were located in the CBZ channels with an extended conformation. Guest exchange experiments were performed on the toluene-solvated CBZ Form II by agitation in PTHF solution. The guest exchange kinetics was monitored by solution NMR, which agreed with the three-dimensional diffusion model. Further investigation revealed that the guest exchange only occurred on the free surface of the toluene-solvated CBZ Form II crystals via a recrystallization mechanism, leading to the formation of a core–shell structure with PTHF merely located in the shell layer. The shell crystal acted as the barrier layer that controlled the diffusion of molecules and consequently the extent of guest exchange, validating the fitted diffusion kinetic model. These results give insight into the guest exchange process between the small molecule guest and polymer guest in a drug IC crystal, and provide implications for a better understanding of guest selectivity and controlling the solid-state properties of drug crystals. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) is a promising two-dimensional polymeric photocatalyst in the field of solar energy conversion. In the past few years many modifications of g-C3N4 have been studied extensively; however, the difficulty in obtaining detailed structural information both on its intrinsic covalent interactions and surrounding bonding environments largely restricts the rational design and development of inherent structure-controlled g-C3N4 based photocatalysts and fundamental understanding of their mechanistic operations. Herein, we demonstrate a high-pressure hydrogenation treatment method for g-C3N4 and introduce 1D 13C and 15N and 2D 15N Radio Frequency-driven Dipolar Recoupling (RFDR) solid-state nuclear magnetic resonance spectroscopy for identifying the structural information and surrounding hydrogen-bonding environment of treated g-C3N4 samples. The surface Brønsted base sites of g-C3N4 samples can be tuned systematically through changing the treatment conditions. We find that the terminal isolated –NH2 and the hydrogenated nitrogen species in treated g-C3N4 samples seem to be the origin of their improved activities for photocatalytic hydrogen evolution and favor the enhancement of light harvesting and carrier transport. The as-prepared HCN400-4-2 sample treated at a pressure of 4 MPa and a temperature of 400 °C for 2 h in a hydrogen atmosphere displays the highest H2 evolution reaction (HER) activity, which is over 26 times higher than that of pristine g-C3N4. [ABSTRACT FROM AUTHOR]

A novel hybrid Na+/Li+ battery is established by using Li2RuO3 as the cathode, 1 M NaClO4 in 1 : 1 EC/PC solution as the electrolyte and metallic sodium as the anode. In the working voltages between 2.0 and 4.0 V, Li2RuO3 delivers a high discharge capacity of 168 mA h g−1 under the current density of 0.1 A g−1 and an excellent capacity retention of about 88.1% after 50 cycles. The cathode also exhibits superior rate capability and long-term cycle life, whose discharge capacity reaches 85 mA h g−1 after 300 cycles at the current density of 1 A g−1. Importantly, both Na+ and Li+ can reversibly intercalate/deintercalate into Li2RuO3 in the same manner as in the typical Li-ion half cell. In addition, ex situ X-ray diffraction patterns of the initial charge and discharge processes as well as after long electrochemical cycles are examined to study its structural evolution. Our studies provide a strong insight into the design and application of novel rechargeable batteries. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting into hydrogen, a renewable and environmentally friendly alternative energy resource, offers a promising way to solve the increasingly urgent energy crisis. We prepare here a series of TiO2–carbon hybrid nanomaterials by heating oleylamine wrapped ultrathin TiO2 nanosheets at different temperatures in an air or inert atmosphere. Photocatalytic experiments show that the activity of these hybrid nanomaterials can be improved and stabilized in comparison to TiO2 nanomaterials without carbon hybridization no matter what shape (ultrathin nanosheets or nanoparticles) and crystalline phase (anatase or rutile) TiO2 presents in the composites. Similar surface species are demonstrated by FTIR and Raman spectroscopy for carbon modified anatase ultrathin nanosheets and nanoparticles, which may result in nearly the same hydrogen production rates of the two photocatalysts. [ABSTRACT FROM AUTHOR]

A molecular compass-like behaviour is found in a perovskite-type cage compound (HIm)2[KCo(CN)6] (HIm = imidazolium cation). The dynamic changes in the HIm cation from the static to rotating state along with the rearrangement of the host cage result in switchable and anisotropic dielectric constants. [ABSTRACT FROM AUTHOR]

The optimal ratio of reaction solutions resulted in excellent performance and product selectivity of CuO/g-C 3 N 4 composites in the photocatalytic CO 2 reduction reaction. A pH-dependent chemical exchange saturation transfer (CEST) imaging nuclear magnetic resonance (NMR) method was used to confirm that CuO modification improves the adsorption capacity of CO 2 .

This work reports an atomic-scale carbon layer configuration tuning strategy induced by a boron dopant. Through regulating the doping level of boron, it was found that the boron dopant not only favors carbon layer growth by strengthening the metallic state of the Ni core, but also enhances the abundance of pyrrolic N species and graphitization degree of carbon by tailoring the carbon/nitrogen atom configuration, thereby contributing to more active pyrrolic N/carbon sites and accelerated interface reaction dynamics. Consequently, the developed Ni@B,N-C catalyst achieves remarkable electrochemical H 2 O 2 production performances with a high selectivity of 95.5% and a yield of 795 mmol g -1 h -1 . In comparison with previous reports in which the boron dopant mainly acts as an electronic structure regulator, this study reveals the tuning effect of boron dopants on the atomic-scale carbon layer configuration, opening up a new avenue for the development of advanced catalysts.

Two-dimensional (2D) hybrid double perovskites have attracted extensive research interest for their fascinating physical properties, such as ferroelectricity, X-ray detection, light response and so on. In addition, ferroelastics, as an important branch of ferroic materials, exhibits wide prospects in mechanical switches, shape memory and templating electronic nanostructures. Here, we designed a 2D phase-transition double perovskite ferroelastic through a structurally progressive strategy. This evolution is core to our construction process from 0D to 1D and AgBi-based 2D. In this way, we successfully synthesized 2D lead-free ferroelastic (DPA) 4 AgBiBr 8 (DPA = 2,2-dimethylpropan-1-aminium) with a high Curie temperature ( T c ), which shows a narrower band gap than 0D (DPA) 4 Bi 2 Br 10 and 1D (DPA) 5 Pb 2 Br 9 . Moreover, the mechanism of structural phase transition and molecular motion are fully characterized by temperature dependent solid-state NMR and single crystal XRD. (DPA) 4 AgBiBr 8 injects power into the discovery of new ferroelastics or the construction and dimensional adjustment in new hybrid double perovskites., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Reduced graphene oxide (rGO) was used to encapsulate Na 3 V 2 (PO 4 ) 2 F 3 @Carbon nanoparticles to overcome its inherent low electronic conductivity and achieve superior sodium storage performance. This as-prepared cathode delivers a remarkable rate performance with a discharge capacity of ca. 64 mA h g -1 at 70C and an ultra-long-term cyclability over 4000 cycles with great capacity retention of 81% at 30C. This excellent performance can be attributed to the favorable combination of fast ionic conductivity of the NASICON structure and the interpenetrating conductive carbon framework; thus bringing a good pseudocapacitive quality to this material. Furthermore, thanks to the good sodium storage properties at low potential, a symmetric full cell can be assembled using Na 3 V 2 (PO 4 ) 2 F 3 @C@rGO as both cathode and anode. The full cell delivers a high discharge capacity of 53 mA h g -1 at 20C rate, further demonstrating the feasibility of this hybrid material for smart grids., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)