A Valence Electron Structure Criterion of Ionic Conductivity of Sr- and Mg-doped LaGaO_3 Ceramics

The valence electron structures of Sr- and Mg-doped LaGaO3 ceramics with different compositions were calculated by Empirical Electron Theory of Solids and Molecules （EET）. A criterion for the ionic conductivity was proposed, i.e. the 1/（nAnB） increases with increasing the ionic conductivity when x or y〈20% （in molar fraction）.

Microwave awakening the n-π^(*) electronic transition in highly crystalline polymeric carbon nitride nanosheets for photocatalytic hydrogen generation

The n-π^(*) electronic transition in polymeric carbon nitride(PCN)can remarkably harvest visible light,which thus potentially promotes the photocatalytic hydrogen H2 generation.However,awaking the n-π^(*) lectronic transition has proven to be a grand challenge.Herein,we reported on the awakening of n-π^(*) electronic transition by microwave thermolysis of urea pellet,which yielded the PCN with absorption edge of 600 nm,near 140 nm red-shift from 460 nm of pristine PCN.The n-π^(*) electronic transition endows PCN with an increased photocata lytic H_(2) generation,with a highest H_(2) rate of 61.7μmol h^(-1) under visible light exposure,which is near 6 times higher than that by using the PCN from the thermolysis of urea pellets in an electric furnace(10.6μmol h^(-1)).Furthermore,the n-π^(*) transition in PCN leads to the longest wavelength of 535 nm that can initiate H2 generation,remarkably longer than the absorption edge of pristine PCN(460 nm).This work manifests the advantages of microwave sintering route to awaken the n-π^(*) electronic transition in PCN for an increased photocata lytic performance.

Solution-processed wafer-scale nanoassembly of conducting polymers enables selective ultratrace nerve agent detection at low power

There is a great interest in developing microelectronic devices based on nanostructured conducting polymers that can selectively electro-couple analytes at high sensitivity and low power.Nanostructured conducting polymers have emerged as promising candidates for this technology due to their excellent stability with low redox potential,high conductivity,and selectivity endowed by chemical functionalization.However,it remains challenging to develop cost-effective and large-scale assembly approaches for functionalized conducting polymers in the practical fabrication of electronic devices.Here,we reported a straightforward waferscale assembly of nanostructured hexafluoroisopropanol functionalized poly(3,4-ethylenedioxythiophene)(PEDOT-HFIP)on smooth substrates.This approach is template-free,solution-processed,and adaptable to conductive and nonconductive substrates.By this approach,the nanostructured PEDOT-HFIPs could be easily integrated onto interdigitated electrodes with intimate ohmic contact.At the optimized space-to-volume ratio,we demonstrated a low-power,sensitive,and selective nerve agent sensing technology using this platform by detecting sarin vapor with a limit of detection(LOD)of 10 ppb and signal strength of 400 times the water interference at the same concentration,offering significant advantages over existing similar technologies.We envision that its easy scale-up,micro size,small power consumption,and combination of high sensitivity and selectivity make it attractive for various wearable platforms.

Increasingπ-electron availability in benzene ring incorporated graphitic carbon nitride for increased photocatalytic hydrogen generation

Increasing the availability ofπ-electron in graphitic carbon nitride(g-C_(3)N_(4))can reduce the band gap and thus enhance the photocatalytic hydrogen(H_(2))generation activity upon exposure to visible light,However,such strategy has not yet been largely applied to increase the H_(2)generation of g-C_(3)N_(4).Herein,we succes s fully increased the amount ofπ-electron in g-C_(3)N_(4)by incorporatingπ-electron-rich benzene rings through copolymerization of melamine and trimesic acid in air.The incorporation of benzene rings not only extends the light absorption of g-C_(3)N_(4)to 650 nm,but also improves the electrical conductivity due to delocalization ofπelectrons in benzene rings.As a result,a 3.4 times enhancement of photocatalytic H_(2)generation was achieved from the g-C_(3)N_(4)with benzene ring incorporation in comparing with that of pristine g-C_(3)N_(4).More interestingly,H_(2)generation still occurs under irradiation of the light ofλ≥490 nm,above the absorption edge of pristine g-C_(3)N_(4)(~460 nm),illustrating the positive effectiveness of incorporated benzene rings on enhancing the H_(2)generation capacity of g-C_(3)N_(4).The present work manifests the advantages of increasingπ-conjugated electrons on designing highly active g-C_(3)N_(4)photocatalysts.

Ni(dmgH)_(2) complex coupled with metal-organic frameworks MIL-101(Cr)for photocatalytic H_(2) evolution under visible light irradiation

Metal-organic frameworks(MOFs)have been tremendously used as photocatalysts for H_(2) generation in recent years.Lacking native active sites(so-called co-catalyst)for H_(2) generation motivates the incorporation of noble metals and their molecular complexes,hydrogenase active site mimics into MOFs to promote H_(2)generation.We herein report an noble-metal-free photocatalytic H_(2) generation system consisting of Erythrosin B dye-sensitized MIL-101(Cr)as a light absorber and Ni(dmgH)_(2) as a co-catalyst.It is found that Ni(dmgH)_(2) can serve as an efficient co-catalyst to boost H_(2) generation in the presence of triethanolamine(TEOA)as an electron donor under visible light irradiation.The optimal MIL-101(Cr)/Ni(dmgH)_(2) hybrid(5 wt%Ni(dmgH)_(2))displays a hydrogen H_(2) rate of 45.5 mmol h^(-1),which is 10 times greater than the control sample without Ni(dmgH)_(2) loading.This paper provides a novel design route for active H_(2) generation systems by combining molecular complexes of earth-abundant metal and MOFs photocatalysts.

SYNTHESIS OF STRONTIUM-AND MAGNESIUM-DOPED LANTHANUM GALLATE BY GLYCINE-NITRATE COMBUSTION METHOD

Sr- and Mg-doped lanthanum gallate powders with the composition of La0.55Sr0.15Ga0.85Mg0.15O2.85were synthesized by a glycine-nitrate combustion method. Powders prepared under different fuel combustion conditions were investigated by XRD and TEM. The results show that, under slightly rich fuel condition, the product powders contain less impurity phases, and powders prepared by the glycine-nitrate combustion contain far less impurity phases and have smaller particle sizes than those prepared by solid-state reaction method or acrylamide polymerization technique.

Spatially Isolated Noble-Metal-Free Redox Cocatalysts on CdS Nanorods for Increased Photocatalytic Hydrogen Generation

Spatially isolated oxidation and reduction cocatalysts on a semiconductor can realize efficient charge separation and thereby lead to increased photocatalytic hydrogen generation. However, the effective preparation of such photocatalysts has proven challenging.Herein, we report the facile synthesis of a novel noblemetal-free CdS/MoS/CoPi ternary photocatalyst via a visible light-induced synthesis route, in which MoSreduction cocatalysts were precisely grown on the two terminals of CdS nanorods, while CoPi oxidation cocatalysts were preferentially anchored onto the sidewalls of CdS nanorods. Such spatially isolated MoSand CoPi redox cocatalysts endow CdS nanorods with a rapid charge separation, which enhances their hydrogen generation activity. The CdS/MoS/CoPi photocatalyst with optimized CoPi amount achieves the highest Hgeneration rate of 206 μmol/h, which is 21 and 2 times higher than that achieved by using CdS alone(9.7 μmol/h) and CdS/MoS(105 μmol/h), respectively. The present work highlights the effectiveness of the spatial isolation of reduction and oxidation sites for efficient charge separation and thereby provides a promising strategy for the preparation of highly active photocatalysts.

Recovering rare earth elements via immobilized red algae from ammonium-rich wastewater

Biotreatment of acidic rare earth mining wastewater via acidophilic living organisms is a promising approach owing to their high tolerance to high concentrations of rare earth elements(REEs);however,simultaneous removal of both REEs and ammonium is generally hindered since most acidophilic organisms are positively charged.Accordingly,immobilization of acidophilic Galdieria sulphuraria(G.sulphuraria)by calcium alginate to improve its affinity to positively charged REEs has been used for simultaneous bioremoval of REEs and ammonium.The results indicate that 97.19%,96.19%,and 98.87%of La,Y,and Sm,respectively,are removed by G.sulphuraria beads(GS-BDs).The adsorption of REEs by calcium alginate beads(BDs)and GS-BDs is well fitted by both pseudo first-order(PFO)and pseudo second-order(PSO)kinetic models,implying that adsorption of REEs involves both physical adsorption caused by affinity of functional groups such as-COO-and -OH and chemical adsorption based on ion exchange of Ca^(2+) with REEs.Notably,GS-BDs exhibit high tolerance to La,Y,and Sm with maximum removal efficiencies of 97.9%,96.6%,and 99.1%,respectively.Furthermore,the ammonium removal efficiency of GS-BDs is higher than that of free G.sulphuraria cells at an initial ammonium concentration of 100 mg L^(-1),while the efficiency decreases when initial concentration of ammonium is higher than 150 mg L^(-1).Last,small size of GS-BDs favors ammonium removal because of their lower mass transfer resistance.This study achieves simultaneous removal of REEs and ammonium from acidic mining drainage,providing a potential strategy for biotreatment of REE tailing wastewater.