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Hierarchically porous silicon nanoflakes were synthesized from natural talc via a mechanochemical reduction method, which showed great potential in the scalable production of silicon nanoflakes due to the abundant precursor and facile strategy. The unique layered structure and chemical composition of talc enabled the formation of two-dimensional nanostructured silicon without any additional templates. As lithium-ion battery anodes, the silicon nanoflakes showed excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

The MgO–CO2–H2O system have a variety of important industrial applications including in catalysis, immobilisation of radionuclides and heavy metals, construction, and mineralisation and permanent storage of anthropogenic CO2. Here, we develop a computational approach to generate phase stability plots for the MgO–CO2–H2O system that do not rely on traditional experimental corrections for the solid phases. We compare the predictions made by several dispersion-corrected density-functional theory schemes, and we include the temperature-dependent Gibbs free energy through the quasi-harmonic approximation. We locate the Artinite phase (Mg2CO3(OH)2·3H2O) within the MgO–CO2–H2O phase stability plot, and we demonstrate that this widely-overlooked hydrated and carbonated phase is metastable and can be stabilised by inhibiting the formation of fully-carbonated stable phases. Similar considerations may apply more broadly to other lesser known phases. These findings provide new insight to explain conflicting results from experimental studies, and demonstrate how this phase can potentially be stabilised by optimising the synthesis conditions. [ABSTRACT FROM AUTHOR]

A lamellar SiC/C composite was synthesized from organoclay via pyrolysis followed by salt-assisted magnesiothermic reduction. The in situ-formed carbon sheet within the restricted interlayer space of clay served as the carbon source and nanotemplate for forming SiC/C. With a large specific surface area, hierarchical porosity, available anchoring sites, good hydrophobicity, and thermal stability, SiC/C proved to be a promising support for Pt. The resulting Pt loaded SiC/C exhibited an excellent toluene oxidation performance. [ABSTRACT FROM AUTHOR]

A silicon flake/nitrogen-doped graphene-like carbon composite was prepared from organoclay via an in situ strategy, involving carbonization followed by low-temperature aluminothermic reduction. The pre-formed carbon sheets within the confined interlayer space of clay acted as nanotemplates for in situ synthesizing silicon flakes. As a lithium-ion battery anode, the composite exhibited excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

Nanostructured silicon is an attractive anode material for next-generation lithium-ion batteries, but its commercialization remains a challenge owing to the energy-intensive, costly, and complex preparation of nanostructured silicon. Herein, one-dimensional (1D) silicon nanorods (SNRs) have been synthesized from natural sepiolite by a simple self-templating synthesis method. The intrinsic crystal structure and chemical composition of sepiolite allow for the maintenance of 1D structures during magnesiothermic reduction without any additional templates and heat scavengers. The as-prepared SNRs showed a large specific surface area (∼122 m2 g−1) and hierarchical porous structure (i.e., macro- and meso-pores). As anodes for lithium-ion batteries, SNRs exhibited a high reversible capacity of 1350 mA h g−1 at 1.0 A g−1 after 100 cycles, and 816 mA h g−1 at 5.0 A g−1 after 500 cycles (with a capacity retention of 98%). With a low-cost precursor and facile approach, this strategy for synthesizing 1D nanostructured Si would be promising in practical production of high-performance anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The selective oxidation of hydrocarbons to the corresponding ketones with solvent-free and molecular oxygen as an oxidant is of great importance in academic and industrial fields in view of economy and environment. In this respect, we present the facile synthesis and characterization of excellent catalysts comprising cobalt nanoparticles encapsulated into graphitic nitrogen-doped carbon nanotubes (Co@GCNs) via one-pot pyrolysis of a chelate compound containing citric acid, melamine, and CoCl2·6H2O. The selective oxidation of ethylbenzene under molecular oxygen and solvent-free conditions is employed as a probe reaction to investigate the catalytic performance; the optimized catalyst shows the best conversion (68%) and selectivity for acetophenone (93%). Combination of the catalytic results of the control group and the different characterization methods demonstrates that high catalytic activity is due to the synergistic effect between metallic cobalt and nitrogen-doped carbon nanotubes. Moreover, the catalyst has high catalytic activity for the aerobic and solvent-free oxidation of other arylalkane substrates. The proposed mechanistic study illustrates that the reaction is a free radical reaction progressing through superoxide radical anions (ṖO2−). [ABSTRACT FROM AUTHOR]

In this paper, cobaltporphyrin is used as a precursor to synthesize carbon nitrides with metal active sites supported on silica spheres by heat treatment (i.e. M-N-C/SiO2). The catalytic performance of M-N-C/SiO2 for ethylbenzene oxidation has been investigated and techniques such as N2 adsorption/desorption isotherm, NH3-TPD, HRTEM, STEM mapping and X-ray photoelectron spectroscopy (XPS) are employed to explore the active sites for ethylbenzene oxidation. XPS results show that cobalt compounds, such as CoOx and metallic Co, as well as cobalt nitrides, such as Co-Nx, are formed after the pyrolysis of cobaltporphyrin. However, according to the NH3-TPD experiment, Co-Nx may be the primary active site. When Co-Nx is poisoned by KSCN, the significant loss of catalytic activity further proves and verifies that Co-Nx instead of CoOx is the primary active site of M-N-C/SiO2 for ethylbenzene oxidation. [ABSTRACT FROM AUTHOR]

Correction for ‘In situ synthesis of a silicon flake/nitrogen-doped graphene-like carbon composite from organoclay for high-performance lithium-ion battery anodes’ by Qingze Chen et al., Chem. Commun., 2019, 55, 2644–2647. [ABSTRACT FROM AUTHOR]

Exploring low-cost and high-performance phosphorus (P) adsorbents is key to controlling P contamination in water. This study evaluated the P adsorption performance of three types of cement: Ordinary Portland cement (OPC), Portland slag cement (PSC), and Portland pozzolana cement (PPC). Furthermore, SEM-EDS, XRD, XPS, and FTIR were employed to reveal the adsorption mechanism. The results showed that the pseudo-second-order model exhibited higher regression coefficients than the pseudo-first-order model, indicating that chemisorption dominated the adsorption process. The Langmuir equation fitted the P adsorption data well, with maximum P adsorption capacities of 245.8, 226.1, and 210.0 mg g -1 for OPC, PSC, and PPC at 25 °C, respectively. P adsorption capacities decreased gradually with increasing initial pH and reached their maximum values at pH 3. The anions of F - , CO 3 2- , and SO 4 2- negatively affected P adsorption due to the competitive adsorption with Ca 2+ . The results of XPS, XRD, and FTIR confirmed that Ca-P precipitates ( i.e. , hydroxyapatite) were the main removal mechanism. A real domestic sewage experiment showed that 0.6 g L -1 OPC effectively reduced the P concentration from 2.4 to below 0.2 mg L -1 , with a dosage cost of 0.034 $ per ton. This study indicated that cement, as a low-cost and efficient P adsorbent, has great potential for application in removing P from acidic and neutral wastewater., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

The MgO-CO 2 -H 2 O system have a variety of important industrial applications including in catalysis, immobilisation of radionuclides and heavy metals, construction, and mineralisation and permanent storage of anthropogenic CO 2 . Here, we develop a computational approach to generate phase stability plots for the MgO-CO 2 -H 2 O system that do not rely on traditional experimental corrections for the solid phases. We compare the predictions made by several dispersion-corrected density-functional theory schemes, and we include the temperature-dependent Gibbs free energy through the quasi-harmonic approximation. We locate the Artinite phase (Mg 2 CO 3 (OH) 2 ·3H 2 O) within the MgO-CO 2 -H 2 O phase stability plot, and we demonstrate that this widely-overlooked hydrated and carbonated phase is metastable and can be stabilised by inhibiting the formation of fully-carbonated stable phases. Similar considerations may apply more broadly to other lesser known phases. These findings provide new insight to explain conflicting results from experimental studies, and demonstrate how this phase can potentially be stabilised by optimising the synthesis conditions.

In this paper, cobaltporphyrin is used as a precursor to synthesize carbon nitrides with metal active sites supported on silica spheres by heat treatment (i.e. M-N-C/SiO2). The catalytic performance of M-N-C/SiO2 for ethylbenzene oxidation has been investigated and techniques such as N2 adsorption/desorption isotherm, NH3-TPD, HRTEM, STEM mapping and X-ray photoelectron spectroscopy (XPS) are employed to explore the active sites for ethylbenzene oxidation. XPS results show that cobalt compounds, such as CoOx and metallic Co, as well as cobalt nitrides, such as Co-Nx, are formed after the pyrolysis of cobaltporphyrin. However, according to the NH3-TPD experiment, Co-Nx may be the primary active site. When Co-Nx is poisoned by KSCN, the significant loss of catalytic activity further proves and verifies that Co-Nx instead of CoOx is the primary active site of M-N-C/SiO2 for ethylbenzene oxidation.