Strontium doped Fe-based porous carbon for highly efficient electrocatalytic ORR and MOR reactions.

The catalytic activity improvement of Fe-based active sites derived from metal organic frameworks toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) remains a major challenge. In this study, the growth of strontium decorated 2-methylimidazole zinc salt (Sr/ZIF-8) is prepared as a carrier to vapor deposited iron formation Sr doped Fe-based nitrogen-doped carbon framework (named as Sr/FeNC). After high-temperature pyrolysis and vapor deposition, strontium carbonate nanocrystals are evenly dispersed on the shrunk dodecahedron carbon frame and multitudinous Fe-based active catalytic sites are embedded in carbon skeleton. The optimal Sr/FeNC-2 catalyst demonstrates the outstanding ORR performance in terms of a half-wave potential of 0.851 V and an onset potential of 0.90 V, while Sr/FeNC-2 exhibits a high current density of 18.2 mA cm-2 and a lower Tafel slope of 21 mV dec-1 in MOR. The exceptional catalytic activity could be ascribed to the synergistic coupling effect of strontium compounds with Fe-based catalytic sites (Fe-Nx, Fe, and iron oxide). In particular, the formation of SrCO3 affects the bonding configuration of the iron species sites, leading to an optimization of the electronic structure within the multihole carbon matrix. The synthetic approach presents a prospective strategy for future endeavors in developing innovative and advanced bifunctional catalysts for ORR and MOR.

Nitrogen- and fluorine-doped bimetallic carbide as active and stable oxygen reduction reaction electrocatalyst.

Nitrogen- and fluorine-doped bimetallic carbide composites with graphite matrix (abbreviated as C19Cr7Mo24/NG and C19Cr7Mo24/FG) are synthesized through carbonization at 1300 °C. The C19Cr7Mo24/NG displays an initial half-wave potential (E1/2) of 0.873 V and suffers merely 3 mV decrease in E1/2 within 60,000 CV cycles for oxygen reduction reaction (ORR) in alkaline media. A H2/O2 fuel cell testing system using the C19Cr7Mo24/NG as cathode maintains 95.9% of the initial peak power density (1.08 W cm-2) within 60,000 cycles. The C19Cr7Mo24/FG shows higher ORR activity than the C19Cr7Mo24/NG. The positive and negative charge centers caused by the N or F dopants are the critical reasons to their high activities. While F and bimetallic carbide more favor electron transfer respectively than the N and monometallic carbide. Their excellent stabilities originate from interactions among atoms due to electron transfer and the intrinsic chemical inertness of graphite and bimetallic carbides.

Boosting activity on copper functionalized biomass graphene by coupling nanocrystalline Nb2O5 as impressive rate capability for supercapacitor and outstanding catalytic activity for oxygen reduction.

A novel and hierarchical porous but cross-linked copper-doped biomass graphene (Cu@HPBG) combined with Nb2O5 (denoted as Nb2O5/Cu@HPBG) is successfully fabricated on a large-scale using fig peels as biomass carbon and copper as the graphitization catalyst. During the synthesis process, basic copper carbonate serves dual functions of pore-forming agent, as well as homogeneous copper provider, and NH3 is employed as a defect-forming agent and N dopant. Owing to the porous hierarchical structure increased availability of contact interface and pseudo capacitance active sites provided by copper and Nb2O5, the assembled asymmetrical supercapacitor (ASC) employing Nb2O5/Cu@HPBG as positive electrode and HPBG as negative electrode can not only widen the stability window range of 0～1.9 V, but also deliver a maximum gravimetric energy density of 82.8 W h kg-1 at the power density of 950.0 W kg-1 and maintain a remarkable cycling stability of 97.1% after 15,000 cycles. Impressively, due to the synergistic enhancement of Cu@HPBG and Nb2O5, the resulting Nb2O5/Cu@HPBG hybrid displays more positive half wave potential (∼0.85 V) and a long-life stability than Pt/C electrode toward oxygen reduction reaction (ORR). Our research provides a feasible strategy to fabricate renewable biomass graphene electroactive composites for large-scale supercapacitor electrodes and efficient ORR catalysts toward energy applications.

Synergistically Coupled Ni/CeOx@C Electrocatalysts for the Hydrogen Evolution Reaction: Remarkable Performance to Pt/C at High Current Density.

Incredibly active electrocatalysts comprising earth-abundant materials that operate as effectively as noble metal catalysts are essential for the sustainable generation of hydrogen through water splitting. However, the vast majority of active catalysts are produced via complicated synthetic processes, making scale-up considerably tricky. In this work, a facile strategy is developed to synthesize superhydrophilic Ni/CeOx nanoparticles (NPs) integrated into porous carbon (Ni/CeOx@C) by a simple two-step synthesis strategy as efficient hydrogen evolution reaction (HER) electrocatalysts in 1.0 M KOH. Benefiting from the electron transport induced by the heterogeneous interface between Ni and CeOx NPs and the superhydrophilic structure of the catalyst, the resultant Ni2Ce1@C/500 catalysts exhibit a low overpotential of 26 and 184 mV at a current density of 10 and 300 mA cm-2, respectively, for HER with a small Tafel slope of 62.03 mV dec-1 and robust durability over 300 h, and its overpotential at a high current density is much better than the benchmark commercial Pt/C. Results revealed that the electronic rearrangement between Ni and CeOx integrated into porous carbon could effectively regulate the local conductivity and charge density. In addition, the oxygen vacancies and Ni/CeOx heterointerface promote water adsorption and hydrogen intermediate dissociation into H2 molecules, which ultimately accelerate the HER reaction kinetics. Notably, the electrochemical results demonstrate that structural optimization by regulating synthesis temperature and metal concentration could improve the surface features contributing to high electrical conductivity and increase the number of electrochemically active sites on the Ni/CeOx@C heterointerface, high crystal purity, and better electrical conductivity, resulting in its exceptional electrocatalytic performance toward the HER. These results indicated that the Ni/CeOx@C electrocatalyst has the potential for practical water-splitting applications because of its controlled production strategy and outstanding Pt-like HER performance.

Promoting CO2 Dynamic Activation via Micro-Engineering Technology for Enhancing Electrochemical CO2 Reduction.

Optimizing the coordination structure and microscopic reaction environment of isolated metal sites is promising for boosting catalytic activity for electrocatalytic CO2 reduction reaction (CO2 RR) but is still challenging to achieve. Herein, a newly electrostatic induced self-assembly strategy for encapsulating isolated Ni-C3 N1 moiety into hollow nano-reactor as I-Ni SA/NHCRs is developed, which achieves FECO  of 94.91% at -0.80 V, the CO partial current density of ≈-15.35 mA cm-2 , superior to that with outer Ni-C2 N2 moiety (94.47%, ≈-12.06 mA cm-2 ), or without hollow structure (92.30%, ≈-5.39 mA cm-2 ), and high FECO of ≈98.41% at 100 mA cm-2 in flow cell. COMSOL multiphysics finite-element method and density functional theory (DFT) calculation illustrate that the excellent activity for I-Ni SA/NHCRs should be attributed to the structure-enhanced kinetics process caused by its hollow nano-reactor structure and unique Ni-C3 N1 moiety, which can enrich electron on Ni sites and positively shift d-band center to the Fermi level to accelerate the adsorption and activation of CO2 molecule and *COOH formation. Meanwhile, this strategy also successfully steers the design of encapsulating isolated iron and cobalt sites into nano-reactor, while I-Ni SA/NHCRs-based zinc-CO2 battery assembled with a peak power density of 2.54 mW cm--2 is achieved.

Recent advances in understanding and design of efficient hydrogen evolution electrocatalysts for water splitting: A comprehensive review.

An unsustainable reliance on fossil fuels is the primary cause of the vast majority of greenhouse gas emissions, which in turn lead to climate change. Green hydrogen (H2), which may be generated by electrolyzing water with renewable power sources, is a possible substitute for fossil fuels. On the other hand, the increasing intricacy of hydrogen evolution electrocatalysts that are presently being explored makes it more challenging to integrate catalytic theories, catalytic fabrication procedures, and characterization techniques. This review will initially present the thermodynamics, kinetics, and associated electrical and structural characteristics for HER electrocatalysts before highlighting design approaches for the electrocatalysts. Secondly, an in-depth discussion regarding the rational design, synthesis, mechanistic insight, and performance improvement of electrocatalysts is centered on both the intrinsic and extrinsic influences. Thirdly, the most recent technological advances in electrocatalytic water-splitting approaches are described. Finally, the difficulties and possibilities associated with generating extremely effective HER electrocatalysts for water-splitting applications are discussed.

Prostate cancer biomarker citrate detection using triaminoguanidinium carbon dots, its applications in live cells and human urine samples.

Citrate is a tricarboxylate, plays vital role in prostate cancer (PC) and the level of citrate is an indicator for PC identification. Herein, triaminoguanidine carbon dots (TAG-CDs) prepared by one step hydrothermal method and used as a citrate receptor. Notably the TAG-CDs without alkaline treatment were highly fluorescent at pH 7 with high quantum yield (11.3%). TAG-CDs were characterized through TEM, XRD, FT-IR, UV-vis and spectrofluorimetry. It is noted that the average size was of 2.8 nm, the presence of highly disordered carbon, retain the functionality of TAG. The absorbance maxima obtained at 294 nm and good emitting response observed at 396 nm. The Y-aromaticity of receptor guanidinium moiety acts as Lewis acid and have peculiar interaction with Lewis base citrate via electrostatic interaction and also protons in the TAG participate hydrogen bonds with citrate, which causes quenching of TAG-CDs. From the obtained linear quenching equation the LOD was found to be 4 nM. The probe expressed high selectivity, high interference tolerance (500 - fold), fast response in 15 mins and good biocompatible. Finally, TAG-CDs utilized for the intracellular imaging of citrate in live MCF-7 cells, it showed good cytotoxicity and delivered contrast images in presence, absence of citrate. TAG-CDs detected the citrate level in human urine samples, the obtained results are validated with HPLC method.

Chrysanthemum-like FeS/Ni3S2 heterostructure nanoarray as a robust bifunctional electrocatalyst for overall water splitting.

The development of a scalable strategy to prepare highly efficient and stable bifunctional electrocatalysts is the key to industrial electrocatalytic water splitting cycles to produce clean hydrogen. Here, a simple and quick one-step hydrothermal method was used to successfully fabricate a three-dimensional core chrysanthemum-like FeS/Ni3S2 heterogeneous nanoarray (FeS/Ni3S2@NF) on a porous nickel foam skeleton. Compared with the monomer Ni3S2@NF, the chrysanthemum-like FeS/ Ni3S2@NF heterostructure nanomaterials have improved catalytic performance in alkaline media, showing low overpotentials of 192 mV (η10) and 130 mV (η-10) for OER and HER, respectively. This study attests that integrated interface engineering and precise morphology control are effective strategies for activating the Ni3+/Ni2+ coupling, promoting charge transfer and improving the intrinsic activity of the material to accelerate the OER reaction kinetics and promote the overall water splitting performance. The scheme can be reasonably applied to the design and development of transition metal sulfide-based electrocatalysts to put into industrial practice of electrochemical water oxidation.

Novel broad-spectrum-driven g-C3N4 with oxygen-linked band and porous defect for photodegradation of bisphenol A, 2-mercaptophenthiazole and ciprofloxacin.

Abundant active oxygen free radicals could efficiently remove refractory organic pollutants. In previous research, the original carbon nitride can form more hydrogen peroxide, however, owing to the limitation of its band structure, the original carbon nitride cannot decompose the hydrogen peroxide to generate more active oxygen free radicals. Herein, this work reports a simple bottom-up synthesis method, which synthesize a broad-spectrum-response carbon nitride (CN-CA) with oxygen-linked band and porous defect structure, while adjusting the band structure, and the introduction of the oxygen-linked band structure can also decompose the hydrogen peroxide produced by the original carbon nitride to form more active oxygen free radicals. Instrumental characterization and analysis of experimental results revealed the important role of oxygen-linked band and porous defects in adjusting the CN-CA energy band structure and improving its visible light absorption. The optimal CN-CA displays an outstanding photocatalytic degradation ability, that degradation rate of bisphenol A (BPA) reaches 99.8% within 150 min, the reaction rate constant of which is 6.77 times higher than that of pure g-C3N4, as also demonstrated with 2-mercaptophenthiazole (MBT) and ciprofloxacin (CIP). Meanwhile, the excellent degradation performance under blue LED (450-462 nm) and green LED (510-520 nm) exhibits the broad-spectrum characteristics of CN-CA. The degradation pathways of BPA and MBT were analyzed via HPLC-MS. Moreover, the primary active species were detected as O2-, OH and h+ based on the trapping experiments and ESR. This research provides a new strategy for g-C3N4 modified by porous defects and oxygen-linked band structure for environmental remediation.

Size-controllable synthesis of zinc ferrite/reduced graphene oxide aerogels: efficient electrochemical sensing of p-nitrophenol.

In this study, a nonaqueous method for the synthesis of size-controlled highly crystalline zinc ferrite/reduced graphene oxide (ZFO/rGO) aerogel was provided by using benzyl alcohol as the medium. In our findings, benzyl alcohol was introduced not only as the solvent, but the structure-directing agent and strong reducing agent during the nucleation and growth of ZnFe2O4 nanoparticles (NPs). The characterization analysis indicated that ZnFe2O4 NPs were immobilized on the multilayer rGO with a controllable size of 12 nm. Moreover, the 3D ZFO/rGO aerogel shows excellent electrochemical property as a facile electrochemical sensor for the detection of p-nitrophenol (p-NP). The ZFO/rGO electrochemical sensing offers the advantages of wide linear range (1-500 µmol l-1), excellent sensitivity (23.985 mA mM-1 cm-2), good stability and selectivity (<8.8%). In addition, the possible reaction mechanism of 3D ZFO/rGO aerogel was explained during the detection process under acidic condition. Significantly, our results not only provided insight into the possible reaction mechanism of 3D ZFO/rGO nanocomposite, but proposed the way for the synthesis of highly crystalline materials through a benzyl alcohol-mediated method.

Reductive Aromatization of Quinols with B2 pin2 as Deoxidizing Agent.

We have demonstrated B2 pin2 as superior deoxidizing agent for the reductive deoxygenation of quinol derivatives under basic conditions. A wide range of highly functionalized phenols were obtained in good yields including a complex drug molecule, which revealed the high functional group tolerance of this protocol.

In situ construction efficient visible-light-driven three-dimensional Polypyrrole/Zn3In2S6 nanoflower to systematically explore the photoreduction of Cr(VI): Performance, factors and mechanism.

Photoreduction of highly toxic Cr(VI) has been regarded as an efficient and green method to achieve water purification. In this process, better charge carrier separation is vital to achieving excellent performance. Besides, it is vital to systematically explore the influencing factors and reaction mechanism. Herein, a novel 3D PPy/Zn3In2S6 nanoflower composite was successfully fabricated via in-situ polymerization. The remarkable conductivity of PPy provides a good electron transport path to facilitate the separation and migration of charge carriers, which benefits to the activity improvement. The results show that 5% PPy/Zn3In2S6 exhibits superior photocatalytic activity with almost 100% Cr(VI) reduction just within 24 min and 99.4% of Methyl orange (MO) is degraded in 25 min. On this basis, factors of different catalyst dosage, concentration, ions and pH under the reduction system were systematically investigated. Especially, different organic acids were in-depth analyzed and the activity could be significantly enhanced just adding 0.1 mmol organic acids. 5% 3D PPy/Zn3In2S6 nanoflower composites (with tartaric acid) exhibits superior photocatalytic activity, which can achieve 100% photoreduction of Cr(VI) just within 6 min. Finally, a possible reaction mechanism was proposed. Moreover, 3D PPy/Zn3In2S6 nanoflower also presented an efficient photodegradation activity for organic pollution.

In situ confined vertical growth of a 1D-CuCo2S4 nanoarray on Ni foam covered by a 3D-PANI mesh layer to form a self-supporting hierarchical structure for high-efficiency oxygen evolution catalysis.

Inspired by the patchwork of artificial turf, where planting in a smaller area can result in a more uniform lawn that grows in one direction, here, we defined the growth position and orientation of a CuCo2S4 nanoarray for the first time by electroplating a PANI mesh layer onto a Ni foam to obtain a self-supporting hierarchical electrode material. The nitrogen species derived from the PANI building blocks act as bridging sites to bind with metal ions, which provides a strong coupling effect for the in situ growth of CuCo2S4. At the same time, the mesh structure of PANI divides the growable location into smaller blocks. Compared with a mesh plane with uniformly distributed nitrogen sites, only a small portion of the nitrogen sites are located on the narrow-width fence structure, which may make it difficult for CuCo2S4 to grow onto the fence structure, thereby limiting the self-growth space and confining CuCo2S4. The uniformly distributed growth sites direct CuCo2S4 to grow perpendicular to the plane while limiting their growth size. The excellent structural features further enhance the electrochemical oxygen evolution activity, and the oxygen evolution overpotential at a current density of 100 mA cm-2 is only 291 mV, which is superior to that of the currently known cobalt-copper-based catalyst materials. In addition, the stable structure provides excellent electrode cyclic stability. The preparation of hierarchical self-supporting cobalt-copper bimetallic sulfide nanoarrays provided a reference direction for other transition metal catalytic materials and provided a basis for industrial applications.

The effect of solvent parameters on properties of iron-based silica binary aerogels as adsorbents.

The magnetic Fe3O4-SiO2 binary aerogel and nonmagnetic α-Fe2O3-SiO2 binary aerogels are obtained by adjusting the solvent type during the solvothermal reaction and varying the Fe/Si proportion in the sol-gel process. The microstructure, surface charge and the formation mechanism of iron-based silica binary aerogels are analyzed by SEM, zeta potential and BET. The influence of the Fe/Si proportion on the surface group and morphology of binary aerogels is also investigated by FTIR and TEM analysis. The adsorption behavior of the iron-based silica binary aerogels on the Congo Red (CR) dye is also discussed by adsorption kinetics model and adsorption isotherm model. In addition, the effects of pH and initial concentration of the solutions, adsorption time and the maximum adsorption capacities for CR of iron-based silica binary aerogels adsorbents are also discussed, respectively. Moreover, the maximum adsorption capacity of as-prepared magnetic Fe3O4-SiO2 binary aerogels for dyes achieved 489.13 mg g-1, the maximum adsorption capacity of nonmagnetic α-Fe2O3-SiO2 reached 454.55 mg g-1, respectively. Thus, the iron-based silica binary aerogels provides valuable clues for the study of other aerogel materials as adsorbents.

Electrochemical CO2 reduction on copper nanoparticles-dispersed carbon aerogels.

The conversion of CO2 into carbon-based fuels via electrochemical reduction is a promising approach to realizing the termination of carbon cycling. Copper (Cu0) is considered to be an effective electrochemical catalyst for such purpose. However, it is limited by its instability and low selectivity. In this work, Cu2+ was embedded into a polycondensation structure of resorcinol (R) and formaldehyde (F) via sol-gel reaction, and the complex was then calcined at high temperature to obtain copper nanoparticles-dispersed carbon aerogels (Cu/CA). The samples were further activated sequentially under CO2 and N2 atmosphere. The final products under different activation temperature of secondary N2 atmosphere were obtained and marked as Cu/CA-CO2-N2-T. The existence of highly dispersed Cu0 on the carbon aerogels was confirmed by XPS and HRTEM, which exhibited attractive activity towards electrochemical CO2 reduction reaction (CO2RR) forming carbon product in 0.1 M KHCO3 aqueous media. Furthermore, the CO2RR product distribution varied under different samples. The sample activated under 700 °C (Cu/CA-CO2-N2-700) with Cu loading c.a. 5.13 wt% showed remarkable CO faradaic efficiency (FE) (75.6%) at low overpotential of -0.49 V. Further calcination led to more exposure of copper, and CO dimerization to C2 product. The high selectivity toward CO by Cu/CA-CO2-N2-700 maybe attributed to their excellent stability in maintaining the metallic nature of Cu component within the hydrophobic carbon aerogels during electrocatalysis, which further prevents the adsorption and reduction of CO on the catalyst.

Layer-by-layer modification of magnetic graphene oxide by chitosan and sodium alginate with enhanced dispersibility for targeted drug delivery and photothermal therapy.

In this work, graphene oxide nanosheets loaded by magnetic iron oxide nanoparticles (mGO) was synthesized and the technique of layer-by-layer (LbL) self-assembly was utilized in the successful production of chitosan/sodium alginate functionalized mGO naocomposites for use in targeted anti-cancer drug delivery and photothermal therapy. The mGO-CS/SA nanocomposites had a diameter of ˜0.5 µm and a thickness of 40-60 nm with superparamagnetic behavior. The modified nanocomposites exhibited a decrease in agglomeration and an increase in stability in biological solution following stability tests. Meanwhile, the nonspecific protein adsorption was strongly suppressed after the modification. The mGO-CS/SA nanocomposites were loaded with doxorubicin hydrochloride (DOX) via π-π stacking and electrostatic attraction with a high drug loading amount (137%, w/w). The DOX-loaded nanocomposites (mGO-CS/SA-DOX) showed improvements in function including enhanced dispersion and noticeable pH-sensitive drug release behavior. Cellular studies denoted magnetically targeted cellular uptake characteristics and excellent photothermal effect of mGO-CS/SA, as well as concentration-dependent cytotoxicity of mGO-CS/SA-DOX. Therefore the functionalization of mGO using chitosan and sodium alginate would be beneficial in biomedical applications.

Selective adsorption of organic dyes by porous hydrophilic silica aerogels from aqueous system.

Hydrophilic silica aerogel (HSA) was obtained by sol-gel method and dried at ambient conditions and further studied for the removal of organic dyes in water. Silica aerogel was characterized by its morphology, porous structure, specific surface area and particle size distribution by scanning electron microscopy, Brunauer-Emmett-Teller and pore size distribution. The HSA after calcination had a specific surface area of 888.73 m2/g and an average particle size of 2.6341 nm. Moreover, adsorption properties of the HSA toward organic dyes - adsorption conditions, kinetics data, and equilibrium model - were investigated. The removal rate of cationic dyes (rhodamine B (RhB), methylene blue (MB) and crystal violet (CV)) by HSA was up to 90%, while the removal rate of anionic dye (acid orange 7) was not more than 30%. The maximum adsorptions were: RhB 191.217 mg/g, MB 51.1601 mg/g and CV 24.85915 mg/g, respectively. Based on the adsorption mechanism of HSA for cationic/anionic dyes, the conclusion confirmed the prospect of HSA as effective adsorbent to treat cationic dyes wastewater.

MXP(M = Co/Ni)@carbon core-shell nanoparticles embedded in 3D cross-linked graphene aerogel derived from seaweed biomass for hydrogen evolution reaction.

Low-cost electrocatalysts play an important role in the hydrogen evolution reaction (HER). Particularly, transition metal phosphides (TMPs) are widely applied in the development of HER electrocatalysts. To improve the poor electrochemical reaction kinetics of HER, we introduce a facile way to synthesize carbon core-shell materials containing cobalt phosphide nanoparticles embedded in different graphene aerogels (GAs) (CoP@C-NPs/GA-x (x = 5, 10 and 20)) using seaweed biomass as precursors. The synthesized CoP@C-NPs/GA-5 exhibits efficient catalytic activity with small overpotentials of 120 and 225 mV at current densities of 10 mA cm-2, along with the low Tafel slopes of 57 and 66 mV dec-1, for HER in acidic and alkaline electrolytes, respectively. Compared with carbon aerogel (CA) containing cobalt phosphide nanoparticles (CoP-NPs@CA), the stability of CoP@C-NPs/GA-5 coated with carbon-shells (∼0.8 nm) was significantly improved in acidic electrolytes. We also prepared carbon core-shell materials containing nickel phosphide nanoparticles embedded in GA (Ni2P@C-NPs/GA) to further expand this synthetic route. The graphene-Ni2P@C aerogel shows a similar morphology and better catalytic activity for HER in acidic and alkaline electrolytes. In this work, the robust three-dimensional (3D) GA matrix with abundant open pores and large surface area provides unblocked channels for electrolyte contact and electronic transfer and enables very close contact between the catalyst and electrolyte. The MxP@C core-shell structure prevents the inactivation of MxP NPs during HER processes, and the thin graphene oxide (GO) layers and 3D CA together build up a 3D conductive matrix, which not only adjusts the volume expansion of MxP NPs as well as preventing their aggregation, but also provides a 3D conductive pathway for rapid charge transfer processes. The present synthetic strategy for phosphides via in situ phosphorization with 3D GA can be extended to other novel high-performance catalysts. The simple synthesis and efficient catalytic activity of MXP@C-NPs/GA indicate good application prospects in HER.

Comparative study of modified/non-modified aluminum and silica aerogels for anionic dye adsorption performance.

Developing effective and low-cost adsorbents is of great significance for controlling water contamination. To eliminate anionic water contaminants, four modified/non-modified aluminum (AlHMD, AlOSSD) and silica (SiHMD, SiOSSD) aerogels have been successfully employed. The four as-prepared aerogels were applied as adsorbents for removal of an anionic dye (acid orange 7, AO) from aqueous solution. Compared to silica aerogels, aluminum aerogels showed efficient adsorption performance for anionic water contaminants. The AO maximum adsorption capacity of Al2O3 aerogel is twice as high as that of SiO2 aerogel. The maximum adsorption capacity of aerogels was in the following order: AlHMD > AlOSSD > SiHMD > SiOSSD. Adsorption kinetics and isotherms of AO dye on the four as-prepared aerogels have also been studied. The kinetic data fitted well with the pseudo first-order kinetics model and the adsorption isotherm could be described by the Langmuir model. Adsorption rate of AO dye was mainly governed by film diffusion and intra-particle diffusion. Based on the adsorption mechanism, this work provides an idea for the design of superior adsorbents for anionic water contaminants.

Integrating AgI/AgBr biphasic heterostructures encased by few layer h-BN with enhanced catalytic activity and stability.

Using freshly prepared water-soluble KBr crystal as facile, low-cost sacrificial template, AgBr nanocubes were synthesized through one-pot precipitation method, then navy bean shaped AgI/AgBr biphasic heterostructures were synthesized through anion-exchange reaction and encased within few-layer h-BN to obtain final product. The obtained heterostructured AgI/AgBr/h-BN composite without plasmonic noble metal nanoparticles was used as stable and high active photocatalyst for dye degradation under visible light irradiation, comparing both with self-prepared normal AgBr, AgBr cubes, AgI/AgBr navy beans and other related catalysts reported in the literature. The significant boosting of activity was attributed to the formation of AgI/AgBr interface and the coupling of few-layer h-BN, the latter of which not only effectively suppresses the reduction of silver ions but greatly enhance the charge separation. Furthermore, it was suggested that the photogenerated holes and superoxide radical were the main active species according to photoelectron chemical measurements, electron spin resonance spin-trap analysis and radical trapping experiments. Finally, the possible mechanism of enhanced photocatalytic activity and stability was discussed and proposed. The work demonstrates that engineering Ag-based semiconductor coupling with h-BN would profit the design strategy for low-cost, solar-driven photocatalysts.