Large BET Surface Area Research Articles

Amino acid assisted-construction of 2D-hierarchical MFI zeolites for adsorption of rhodamine B

Hierarchical and two-dimensional (2D) zeolites have drawn much attention in catalysis and separation process due to their fast mass transfer. However, the facile manipulation in controllable mesopore volumes and morphologies for hierarchical nanozeolites is full of challenges. Herein, a facile strategy is presented for the synthesis of single-crystalline 2D hierarchical MFI zeolite nanosheets (HNSs) with tunable mesopore volumes through the amino acid-assisted crystallization of nucleated amorphous silicon precursors (NASPs). The tailored synthesis of HNSs with controllable aspect ratios ((Lc + La)/Lb), b-axis thicknesses (a few tens of nanometers) and mesopore volumes is achieved by adjusting the preparation of the NASPs and the amount of amino acid in the synthesis mixture. The HNSs exhibit large BET surface area (>400 m2/g), high micropore volume (0.16–0.18 cm3 g−1) as well as rich mesopore volume (>0.10 cm3 g−1), indicating the high crystallinity of the hierarchical zeolite nanosheets. Specially, the higher adsorption capability and faster adsorption rate for the dye (Rhodamine B) adsorption demonstrate the excellent performance of the hierarchical zeolite nanosheets, which exhibit the maximum adsorption capacity of 115.7 mg g−1. The controllable manipulation of mesoporous volumes and morphologies in MFI zeolites represents a significant contribution to the field of zeolite microstructure engineering.

Facile Synthesis of Zeolite NaX from Natural Attapulgite Clay for Pb2+ Adsorption

The synthesis of zeolites from natural aluminosilicate minerals has drawn extensive attention due to its significant utility in greening the zeolite manufacturing process. In this study, pure-phase NaX zeolite was synthesized via a low-temperature hydrothermal method, utilizing natural, low-quality attapulgite clay as the raw material. Acidified clay was fully activated through alkali fusion at 200 °C, and the impact of alkali fusion temperature, H2O/Na2O ratio, aging temperature, and crystallization time on the resulting crystalline NaX zeolite was investigated. The optimal conditions for obtaining pure NaX zeolite were determined to be alkali melting at 200 °C for 4 h, an H2O/Na2O ratio of 50, aging at 40 °C, and a crystallization period of 11 h at 90 °C. With a large BET surface area of 328.43 m2/g, the obtained NaX zeolite was used to adsorb Pb2+ from wastewater with a removal rate of 95%. This research provides a valuable method for the extensive and efficient utilization of low-grade natural attapulgite clay. Moreover, this is the first report on the synthesis of pure-phase NaX zeolite using only low-quality natural attapulgite clay as raw material through an atmospheric pressure water bath method.

Insights into the migration mechanism of extracellular antibiotic resistance genes during struvite recovery using synthetic wastewater

In recent, the complexation of extracellular antibiotic resistance genes (eARGs) with environmental particles has been getting significant concerns, since eARGs can consequently disseminate, propagate and pose ecological risks to the environment. This study focused on eARGs complexing with struvite (MgNH4PO4·6H2O) particles in struvite recovery by using synthetic wastewater. The adsorption capacities of eARGs by struvite crystals with different morphologies were firstly examined. Results revealed that struvite crystals possessed the maximum eARGs adsorption capacity of 7.95 × 1012-1.76 × 1013 copies/g. The evolution of struvite morphologies from regular polyhedron to needle-like, coupled with larger BET surface area, resulted in a matching increase relationship of eARGs adsorption. Electrostatic interaction and covalent binding were the predominant forces between eARGs and struvite crystals, attributed to the Mg[H2O]62+ octahedra in the struvite crystallite and the phosphate backbone with its external position in eARGs molecule. The eARGs adsorption in struvite crystallization displayed a “U” curve with the minimum values of 3.57 × 1012-7.28 × 1012 copies/g at pH 8.8, which was ascribed to the excessive existence of Mg2+ ions in the liquid. Despite the gradual increase in the Mg:P molar ratio from 1.0 to 2.5 during crystallization, the abundance of eARGs on recovered solids displayed twice dramatic declines with two or three orders of magnitude lower, which was attributed to the formation and binding saturation of eARGs-Mg chelate, as well as the non-negligible evolution of magnesium species under different pH values. These outcomes provide new insights into the migration behavior of eARGs during struvite recovery from wastewater.

Recycling of Sewage Sludge: Synthesis and Application of Sludge-Based Activated Carbon in the Efficient Removal of Cadmium (II) and Lead (II) from Wastewater.

The limited supply of drinking water has aroused people's curiosity in recent decades. Adsorption is a popular method for removing hazardous substances from wastewater, especially heavy metals, as it is cheap, highly efficient, and easy to use. In this work, a new sludge-based activated carbon adsorbent (thickened samples SBAC1 and un-thickened samples SBAC2) was developed to remove hazardous metals such as cadmium (Cd+2) and lead (Pb+2) from an aqueous solution. The chemical structure and surface morphology of the produced SBAC1 and SBAC2 were investigated using a range of analytical tools such as CHNS, BET, FT-IR, XRD, XRF, SEM, TEM, N2 adsorption/desorption isothermal, and zeta potential. BET surface areas were examined and SBAC2 was found to have a larger BET surface area (498.386 m2/g) than SBAC1 (336.339 m2/g). While the average pore size was 10-100 nm for SBAC1 and 45-50 nm for SBAC2. SBAC1 and SBAC2 eliminated approximately 99.99% of Cd+2 and Pb+2 out the water under all conditions tested. The results of the adsorption of Cd+2 and Pb+2 were in good agreement with the pseudo-second-order equation (R2 = 1.00). Under the experimental conditions, the Cd+2 and Pb+2 adsorption equilibrium data were effectively linked to the Langmuir and Freundlich equations for SBAC1 and SBAC2, respectively. The regeneration showed a high recyclability for the fabricated SBAC1 and SBAC2 during five consecutive reuse cycles. As a result, the produced SBAC1 and SBAC2 are attractive adsorbents for the elimination of heavy metals from various environmental and industrial wastewater samples.

Effect of sintering temperature on magnetic, catalytic and photocatalytic properties of Cu-Co-Mn ferrite catalyst

Wastewater pollution is a pressing environmental issue, necessitating effective remediation strategies to mitigate its impact. This study investigates the use of an efficient catalyst for degrading nitrophenols by converting them into useful aromatic amines, which are crucial building blocks for many pharma industries, and photodegradation of various dyes in their unitary solution as well as in mixture. The Cu-Co-Mn ferrite was synthesized using the sol-gel process and sintered at different temperatures. Structural analysis using XRD and Rietveld refinement revealed a crystal structure corresponding to the Fd3‾m space group having high purity in all the samples. Additionally, the impact of sintering temperature on the magnetic features of the phases were also studied and the findings suggest that all the phases exhibit ferromagnetic behaviour, which means they can be easily separated from reaction mixtures using an external magnetic field. It was also found that higher sintering temperatures lead to a rise in saturation magnetization and magnetic moment with decrease in coercivity (Hc). Further, it was observed that Curie temperature (Tc) increases with increase in sintering temperature with the exception of CFM400. The catalytic performance of all the catalysts, including CFM400, CFM500, CFM600, CFM800, and CFM1000, was evaluated and the results indicate that CFM400 exhibits the highest catalytic activity for nitrophenols reduction and photodegradation of dyes, which could be accredited to its larger BET surface area and lower PL intensity. Overall, the structural and magnetic features of the catalyst’s sheds light on the underlying mechanisms governing their catalytic activity. These insights offer valuable guidance in the designing and development of effective catalysts for sustainable wastewater treatment practices, emphasizing the importance of considering both structural and magnetic features in catalyst design.

Post-synthesis modification cationic covalent organic frameworks with multiple adsorption sites for efficient iodine adsorption

With the advancement of nuclear energy, the safe disposal of radioactive materials, especially nuclear waste containing iodine, has become a serious issue attracting attention. Thus, reported here is a general strategy for creating a cationic covalent organic framework (TAPT-COF-AB) containing a significant number of free bromide ions through post-synthesis modification of a hydroxy-functionalized COF (TAPT-COF-OH) and exploration of the ionic covalent organic frameworks (iCOFs) for iodine adsorption. Owing to TAPT-COF-AB retaining good crystallinity and large BET surface area, it exhibits excellent adsorption capacity for iodine with a maximum adsorption capacity of up to 5.05 g/g. The results indicate an increase of 1.44 g/g compared to TAPT-COF-OH (3.61 g/g) and maintained its high performance even after five cycles. Furthermore, the calculation of density functional theory (DFT) shows the significant chemical interaction between iodine and the material frameworks and supports the accuracy of the experiment. The results performed that including ionic groups increased the affinity between COFs and iodine, thereby enhancing the iodine adsorption properties. This work opens an avenue for constructing functional COFs for environmentally relevant critical applications.

Triple Templates Directed Synthesis of Nitrogen-Doped Hierarchically Porous Carbons from Pyridine Rich Monomer as Efficient and Reversible SO2 Adsorbents.

Herein, a variety of 2,6-diaminopyridine (DAP) derived nitrogen-doped hierarchically porous carbon (DAP-NHPC-T) prepared from carbonization-induced structure transformation of DAP-Zn-SiO2-P123 nanocomposites are reported, which are facilely prepared from solvent-free co-assembly of block copolymer templates P123 with pyridine-rich monomer of DAP, Zn(NO3)2 and tetramethoxysilane. In the pyrolysis process, P123 and SiO2 templates promote the formation of mesoporous and supermicroporous structures in the DAP-NHPC-T, while high-temperature volatilization of Zn contributed to generation of micropores. The DAP-NHPC-T possess large BET surface areas (≈956-1126 m2g-1), hierarchical porosity with micro-supermicro-mesoporous feature and high nitrogen contents (≈10.44-5.99 at%) with tunable density of pyridine-based nitrogen sites (≈5.99-3.32 at%), exhibiting good accessibility and reinforced interaction with SO2. Consequently, the DAP-NHPC-T show high SO2 capacity (14.7mmolg-1, 25°C and 1.0bar) and SO2/CO2/N2 IAST selectivities, extraordinary dynamic breakthrough separation efficiency and cycling stability, far beyond any other reported nitrogen-doped metal-free carbon. As verified by in situ spectroscopy and theoretical calculations, the pyridine-based nitrogen sites of the DAP-NHPC-T boost SO2 adsorption via the unique charge transfer, the adsorption mechanism and reaction model have been finally clarified.

Tree-inspired semiconductor-on-ceramic 2D/1D heterostructure for efficient CO2 photoreduction

Two-dimension nanosheets are ideal photocatalysts for CO2 reduction due to their high exposure of active sites and short charge transfer pathway. However, 2D photocatalysts have a tendency to agglomeration, thus compromising the performance of photocatalytic CO2 reduction. Trees, one of the most important plants for photosynthesis, have a unique “leaf-on-branch” structure. This unique two-dimension/one-dimension (2D/1D) configuration maximizes the adsorption of CO2 molecules and light harvesting. Herein, a tree-inspired semiconductor-on-ceramic 2D/1D heterostructure for efficient photocatalytic CO2 reduction is reported. The cobalt silicate (CoSi) nanosheets (∼0.68 nm) are in situ grown on the surfaces of hydroxyapatite (HAP) nanowires, creating a well-defined 2D/1D hierarchical structure. The vertical alignment of ultrathin CoSi nanosheets on the HAP nanowires effectively suppresses their agglomeration, leading to a large BET surface area (106.45 m2/g) and excellent CO2 adsorption (8.00 cm3 g−1). The results of photoelectrochemical characterization demonstrate that the 2D/1D hierarchical structure is powerful to expedite charge transfer. As a result, the gas generation rate of CO is as high as 28780 μmol g−1 h−1 over the CoSi-on-HAP 2D/1D heterostructure. In addition, the electron transfer mechanism and reaction pathways of CO2 reduction are revealed by in situ irradiated XPS and in situ DRIFT spectra.

Conversion of municipal sewage sludge into biogenic multi-walled carbon nanotubes and hydrogen using X-Mo/MgO (X = Co, Fe, Ni) catalysts through pyrolysis-chemical vapor deposition process

Utilization of municipal sewage sludge as a feedstock for synthesizing biogenic multi-walled carbon nanotubes (MWCNTs) and recovering H2 via pyrolysis-chemical vapor deposition (CVD) was explored. The research centered on investigating the impact of X-Mo/MgO catalysts (X = Co, Fe, Ni, and X: Mo: MgO mass ratio of 3:1:6) on the conversion of pyrolysis gases from the sludge at the CVD temperatures of 600–––800 °C. The results demonstrate that the catalyst efficiency is enhanced when CO2 is captured from pyrolysis gas prior to the CVD reactor (here, with a calcium-based sorbent). The three X-Mo/MgO catalysts showed the highest MWCNT and H2 yields at 700 °C compared to other temperatures. The Co-Mo/MgO catalyst exhibited the highest MWCNT production (2.9 wt% per feedstock) and H2 yield (140.7 mL per g of sludge) at 700 °C. The higher yield could be related to the smaller size of the metal particles of the spent catalyst. Furthermore, Co-Mo/MgO at 700 °C grown MWCNTs had more uniform diameter distribution and larger BET surface area. Notably, the produced MWCNTs were doped by N and S heteroatoms due to the presence of these elements in the sludge and the doping extent could be managed by controlling the CVD temperature, opening the pathway for customization of MWCNT properties. The highest doping levels were observed for MWCNTs grown on Fe-Mo/MgO at 600 °C (N − 3.4 at% and S – 2.3 at%) by XPS. According to these results, the pyrolysis-CVD process could be a feasible technique for the conversion of municipal sewage sludge into valuable biogenic MWCNTs and H2. The use of Co-Mo/MgO and Ni-Mo/MgO catalysts exhibited some advantages (e.g., high MWCNTs and H2 yields) compared to Fe-Mo/MgO catalysts.

Synthesis of silver‐doped TiO2 nanoparticles with highly efficient adsorption of Congo red

AbstractTiO2 nanoparticles (NPs) doped with Ag were produced through a solvothermal method, with varying amounts of silver doping ranging from 0.5% to 1.5%. The samples were analyzed for crystallite sizes, structure, and metallic bondings using XRD, SEM, EDXS, and FTIR techniques. The BET surface areas were determined through nitrogen adsorption isotherms. The efficiency of the silver‐doped TiO2 NPs for removing Congo red (CR) was tested through adsorption experiments. The results showed that the synthesized TiO2 NPs doped with Ag were uniformly spherical in shape, with tiny average sizes ranging from 7.97 to 12.74 nm and large BET surface areas (98.41–166.1 m2 g−1). The silver‐doped TiO2 samples with a 0.5% Ag doping amount exhibited the highest adsorption capacity in CR removal, with a maximum adsorption capacity of 454.55 mg of dye per gram of adsorbent and a lower contact time of 20 min than other metal oxide NPs. The CR adsorption onto 0.5% Ag‐TiO2 obeyed the Langmuir isotherm model (R2 = 0.989), and the adsorption followed a pseudo‐second‐order kinetic equation. The adsorbent could be efficiently reused for five consecutive cycles to remove CR.

Locust leaves-derived biochar coupled CuxO composites for efficient electrocatalytic CO2 reduction

The electrochemical CO2 reduction reaction (CO2RR) to obtain high-valued product is considered to be a promising strategy for greenhouse effect mitigation. However, the development of low-cost electrocatalysts with excellent electrocatalytic performance is necessary. In this study, we developed a serials of locust leaves-derived CuxO@C composites with large surface area and high CO2 adsorption ability. Among them, the CuxO@C-2 with optimal C content (0.10 g) displays the highest FEC2H4 of 41.3 % at −1.08 V vs. RHE, which is 1.7 times higher than that of pure CuxO sample. The enhanced performance for CO2RR may be attributed to the large BET surface area, improved adsorption ability of CO2 and exposed abundant active sites. The work provides a feasible strategy for configuring CuxO-based materials with high adsorption capacity and more reaction activity sites.

Ammonia-free selective catalytic reduction of NO by coal-based activated carbon supported Cu-Mn oxides at low temperature

Selective catalytic reduction of ammonia is the most widely technology for removing NOx, but there were serious ammonia leakage and high temperature reaction. To overcome these limitations, a series of Cu and Mn metals supported on coal-based activated carbon (CuxMny/CAC) were synthesized, for ammonia-free catalytic reduction of NO at low temperature. The results demonstrated that Cu and/or Mn catalysts significantly improved low-temperature SCR performance and char-NO reaction selectivity when combined with CAC. In particular, Cu6Mn4/CAC showed excellent NO removal rate (100 %) and higher char-NO selectively (111.21 mg/g) at 290 ℃ under O2-rich condition. Characterization analyses revealed that Cu6Mn4/CAC had a larger BET surface area and preferable pore structure, and the synergistic effect mainly came from the redox cycle between CuOx and MnOy, as well as the interaction between Cu-Mn oxides and the CAC support. Cu-Mn metals promote the adsorption of NO and O2 in the char-NO process, leading to the generation of abundant surface adsorption oxygen species (O2-, O22-, and O-) and C(O) complex, which facilitated the char-NO reaction. Therefore, a mechanism for ammoniac-free selective catalytic reduction of NO by Cu6Mn4/CAC was proposed. These finding provide new insights for developing low-temperature ammonia-free denitrification technology and improving high-value utilization of coal resources.

Covalent organic framework‐derived Fe, Co‐nitrogen codoped carbon as a bifunctional electrocatalyst for rechargeable efficient Zn–air batteries

AbstractThe development of cathode materials with controllable physicochemical structures and explicit catalytic sites is important in rechargeable Zn–air batteries (ZABs). Covalent organic frameworks (COFs) have garnered increasing attention owing to their facile synthesis methods, ordered pore structure, and selectivity of functional groups. However, the sluggish kinetics of oxygen evolution reaction (OER) or oxygen reduction reaction (ORR) inhibit their practical applications in ZABs. Herein, nucleophilic substitution is adopted to synthesize pyridine bi‐triazine covalent organic framework (denoted as O‐COF), and meanwhile, ionothermal conversion synthesis is employed to load MOx (M=Fe, Co) onto carbon nanosheet (named as FeCo@NC) to modulate the electronic structure. The Fe, Co‐N codoped carbon material possesses a large portion of pyridinic N and M‐N, high graphitization, and a larger BET surface area. An outstanding bifunctional activity has been exhibited in FeCo@NC, which provides a small voltage at 10 mA cm−2 for OER (E10 = 1.67 V) and a remarkable half‐wave voltage for ORR (E1/2 = 0.86 V). More impressively, when assembling ZABs, it displays notable rate performance, significant specific capacity (783.9 mAh gZn−1), and satisfactory long‐term endurance. This method of regulating covalent organic framework and ionothermal synthesis can be extended to design diverse catalysts.

One-Pot Synthesis of Ce-SSZ-39 Zeolite with Performance in the NH3-SCR Reaction.

Cu-SSZ-39 zeolite with 8-membered rings is regarded as a very promising catalyst in the NH3-SCR reaction, but its hydrothermal stability still remains to be improved. One of the solutions to promote hydrothermal stability is the insertion of rare earth elements in the product. Nevertheless, normal ion exchange of rare earth elements limits their contents in the zeolite product due to their large hydrated ionic radius and alkaline environment under hydrothermal conditions. Herein, we for the first time present a new method for the one-pot synthesis of Ce-SSZ-39 zeolite under solvent-free conditions. The key to success is the use of Ce-FAU zeolite as a precursor. The obtained product shows good crystallinity, sheet-like morphology, large BET surface area, and 4-coordinated Al species. Detailed investigations illustrate that Ce species in the Cu/Ce-SSZ-39 zeolite micropore can prevent the dealumination and thus formation of CuAlOx species during hydrothermal aging at 850 °C for 16 h, giving the excellent hydrothermal stability and thus showing the excellent catalytic performance in the NH3-SCR reaction. One-pot synthesis of Ce-SSZ-39 zeolite with excellent catalytic performance might open a new door for developing very efficient selective catalytic reduction (SCR) catalysts in near future.

In situ impregnation of cobalt‐doped tungstophosphoric acid on MOF‐801 toward enhanced catalytic activity for esterification

Development of an energy‐efficient and economical route is necessary for society to synthesize green biofuels. Herein, cobalt‐doped tungstophosphoric acid (Co‐HPW) is in‐situ impregnated in the Zr‐based metal–organic framework (MOF‐801) forming composite of Co‐HPW/MOF‐801. The chemical composition, morphology, and acidic sites of the Co‐HPW/MOF‐801 composite were analyzed through x‐ray diffractometer (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy‐dispersive x‐ray spectroscopy (EDS), thermogravimetric analysis (TG), N2 physisorption, ammonia temperature‐programmed desorption (NH3‐TPD), pyridine‐adsorbed infrared spectra (Py‐FTIR), and x‐ray photoelectron spectroscopy (XPS). The catalytic performance of the as‐synthesized catalyst was explored to catalyze esterification of lauric acid (LA) with methanol. The outcomes revealed that the Co‐HPW/MOF‐801 nanocatalyst achieved a high conversion of 86.3% under the optimized reaction condition (catalyst amount of 0.15 g, temperature of 100°C, time of 4 h, and methanol/LA molar ratio of 20:1). The excellent catalytical performance is mainly due to the large BET surface area, exposure of more active centers from available pore structure, and simultaneous possession of high Lewis and Brønsted acidity. Furthermore, the kinetic study revealed that the reaction process was kinetically controlled and the activation energy was found to be 42.1 kJ/mol. The results suggest that the synthesized Co‐HPW/MOF‐801 nanocatalyst is an environmental greenness, low cost, and suitable for easy scale‐up for the production of biofuels.

Facile Synthesis and Li-Electroactivity of Cobalt Oxide Based on Resources Recovered from Waste Lithium-Ion Batteries

In this study, cobalt oxide (Co3O4) powder was prepared by simple precipitation and heat-treatment process of cobalt sulfate that is recovered from waste lithium-ion batteries (LIBs), and the effect of heat-treatment on surface properties of as-synthesized Co(OH)2 powder was systematically investigated. With different heat-treatment conditions, a phase of Co(OH)2 is transformed into CoOOH and Co3O4. The result showed that the porous and large BET surface area (ca. 116 m2/g) of Co3O4 powder was prepared at 200°C for 12 h. In addition, the lithium electroactivity of Co3O4 powder was investigated. When evaluated as an anode material for LIB, it exhibited good electrochemical performance with a specific capacity of about 500 mAh g–1 at a current density of C/5 after 50 cycles, which indicates better than those of commercial graphite anode material.

Facile construction of a cobalt-incorporated N-doped porous carbon from biomass for highly efficient removal of tetracycline

The performance of heterogeneous carbon-based catalysts in advanced oxidation processes (AOPs) significantly relies on their structure and surface active sites. Herein, the cobalt-incorporated N-doped porous carbon (Co-NC) was successfully prepared from tannin by utilizing its strong ability to coordinate with metal ions. The characterization results revealed that Co-NC-900 possessed a porous structure with abundant mesopores, a relatively large BET surface area (187.16 m2/g), multivalent cobalt species (Co0, Co2+, Co3+) and optimal surface nitrogen sites. As a result, Co-NC-900 demonstrated efficient PMS activation, resulting in a 97.4% removal of tetracycline (TC), along with a rate constant (kobs) of 0.131 min−1 and TOC removal efficiency of 55.3% within 30 min. The analysis of radical inhibition and EPR results revealed that TC degradation was attributed to both non-radical (1O2) and radical (•OH and SO4•-) pathways. In addition, the outperformance of Co-NC-900 compared to Co-C-900 and NC-900 highlights the essential contributions of both Co and N in PMS activation. Mechanism studies have revealed that the presence of multivalent Co species promotes the Co-based redox cycle. This, in association with the enhanced electron transfer efficiency facilitated by N doping sites, accelerates the rapid generation of reactive oxygen species (ROSs). This work provides a straightforward strategy to fabricate transition metal-incorporated N-doped porous carbon catalysts from eco-friendly biomass, contributing to the effective treatment of organic contaminant.

High efficiency simultaneous adsorption of rare earth elements from aqueous solutions using carbon xerogel-chitosan composite

ABSTRACT This study investigated the simultaneous sorption of rare earth elements (REEs) from acidic media using carbon xerogel functionalised with chitosan. The combined carbon xerogel with chitosan that was synthesised has a sphere-like structure and a larger BET surface area (275 m2 g−1) than pure carbon xerogel alone (228 m2 g−1). To determine the optimal conditions, adsorption of REEs was established under different variables, including pH, contact time, initial concentration, adsorbent wt. and temperature, as well as desorption experiments. The adsorption isotherms showed that both the Freundlich and Langmuir models were followed, in addition to a pseudo-second order kinetic model. The adsorption is likely exothermic, which confirms it is favourable at low temperatures, and a dissociative adsorption process is involved, according to analysis of thermodynamic state functions. Langmuir calculations revealed that the maximum amount of REEs that were adsorbed was 164 mg/g. Because of its superior adsorption capacity and simplicity in using a recycled material following several desorption cycles, carbon xerogel-chitosan is being employed as a novel adsorbent material to remove REEs from aqueous solutions.

Formation of GO supported CoS2@MoS2 heterostructures with efficient electrocatalysis for water splitting

Novel bifunctional catalyst, MoS2@CoS2 nanospheres grown on graphene oxide (CMS/GO), was successfully prepared. CMS/GO shows promising activity toward both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), with lower overpotentials of 90 mV for HER and 260 mV for OER at a current density of 10 mA/cm2. The corresponding Tafel slopes are 48 mV/dec and 52 mV/dec, respectively. The catalytic ability is significantly improved, which may derives from the synergistic effect between CoS2 and MoS2, the larger electrochemically active specific surface area coming from the larger BET surface area, the enhanced conductivity and active defects.

Tricomponent direct co-assembly to nitrogen-doped, ordered mesoporous carbon@silica frameworks with enhanced nitrogen stability and multi-functionalities

Ordered mesoporous carbon@silica hybrid frameworks with high nitrogen content and good stabilities show great significance to improve their functionalities. Herein, we report novel nitrogen-doped (3.51 ∼ 4.62 wt%) and ordered mesoporous carbon@silica frameworks (N-OMC@SiO2) with reinforced nitrogen stability. The N-OMC@SiO2 were designed from tricomponent direct co-assembly between block copolymer template and mixed precursors containing urea and tetramethoxysilane without using additional solvent. The N-OMC@SiO2 have large BET surface areas (444.3 ∼ 674.9 m2/g), uniform mesoporous channels (5.8 ∼ 10.9 nm) with well-defined hexagonal symmetry, and stable carbon@silica “reinforced concrete” framework that can be transformed into carbon@silicon by controllable reduction. The nitrogen sites were firmly embedded into their frameworks via the formation of Si-N bonding. Thus, the resulted N-OMC@SiO2 exhibit multi-functionalities and enhanced recyclability in acid waste gas capture and gaseous sulfides catalytic utilization, better than many reported porous adsorbents and catalysts. This study may help develop stable and efficient N-OMCs nanocomposites for acidic gas selective removal.