Generic heterostructure interfaces bound to Co9S8 for efficient overall water splitting supported by photothermal.

The increase of reaction temperature of electrocatalysts and the construction of heterogeneous structures is regarded as an efficient method to improve the electrocatalytic water splitting activity. Here, we report an approach to enhance the local heat and active sites of the catalyst by building a heterostructure with Co9S8 to significantly improve its electrocatalytic performance. The as-fabricated Co9S8@Ce-NiCo LDH/NF electrode possesses a notable photothermal ability, as it effectively converts near-infrared (NIR) light into the local heat, owing to its significant optical absorption. Leveraging these favorable qualities, the prepared Co9S8@Ce-NiCo LDH/NF electrode showed impressive performance in both hydrogen evolution reaction (HER) (η100 = 144 mV) and oxygen evolution reaction (OER) (η100 = 229 mV) under NIR light. Compared to the absence of the NIR light, the presence of NIR irradiation leads to a 24.6 % increase in catalytic efficiency for HER and a 15.8 % increase for OER. Additionally, other dual-functional electrocatalysts like NiCo-P, NiFeMo, and NiFe(OH)x also demonstrated significantly enhanced photothermal effects and improved catalytic performance owing to the augmented photothermal conversion when combined with Co9S8. This work offers novel pathways for the development of photothermal-electrocatalytic systems that facilitate economically efficient and energy-conserving overall water splitting processes.

Constructing a noble-metal-free 0D/2D CdS/SnS2heterojunction for efficient visible-light-driven photocatalytic pollutant degradation and hydrogen generation.

Semiconductor photocatalysis has attracted the attention of a wide audience for its outstanding capabilities in water purification and energy conversion. Herein, a noble-metal-free nanoheterojunction is created by planting zero-dimensional (0D) CdS nanograins, of 10-20 nm in size, on the surface of 2D SnS2nanosheets (NSs) using anin situchemical bathing deposition process, where SnS2NSs have an average diameter of 400 nm and thicknesses of less than 20 nm. The possible formation mechanism of the CdS/SnS2(CS/SS) heterogeneous nanostructure is elaborated upon. The catalytic activities over CS/SS nanocomposites for the photodegradation of organic dye and hydrogen evolution from photolysis water splitting are examined under visible light irradiation. The apparent rate constant (k) of the optimal CS/SS-3 composite in the decontamination of methylene blue (MB) is up to 3.34 and 1.87 times as high as that of pristine SnS2and pure CdS counterparts, respectively. The optimized CS/SS-3 sample consistently achieves the highest photocatalytic hydrogen production rate, at 10.3 and 5.7 folds higher than that of solo SnS2and CdS panels, respectively. The boosted photocatalytic capacities of CdS/SnS2heterostructures are essentially attributed to the formation of the closely interfacial incorporation of CdS and SnS2semiconductors, resulting in the effective charge transportation and spatial separation of the photoinduced electron-hole pairs. Furthermore, the traditional type-II charge transfer pathway is proposed based on the perfect band structure and the free radical experiment results.

ZnS spheres assembled from nanoparticles confined in bagasse-based carbon nanosheets for enhanced potassium storage.

Transition metal zinc sulfide (ZnS) is a promising anode material for potassium ion batteries due to its rich abundance and high capacity (conversion/alloy dual mechanism), while still suffering the drawbacks of sluggish kinetics process and structural degradation, which restrict its practical application. Herein, ZnS spheres assembled from nanoparticles embedded in carbon nanosheets (ZnS/C@C) were synthesized with alkali-activated agricultural waste bagasse as the carbon precursor. The removal of lignin and hemicellulose by pre-treatment of bagasse with alkali solutions opens ionic diffusion channels and promotes adsorption of Zn2+by bagasse, which is crucial for the growth of ZnS in bagasse sheets and the suppression of ZnS particle size during hydrothermal processes. Benefiting from the synergistic effects between robust embedded structure, carbon conductive network and the nanoscale nature of ZnS, the ZnS/C@C exhibited enhanced performance with high capacity (374.7 mA h g-1at 0.2 A g-1) and rate performance (195.9 mA h g-1at 2.0 A g-1). Kinetic studies further demonstrate that ZnS/C@C electrodes possess faster K+transport kinetics and lower interfacial impedance. This work provides a reference for the construction of robust embedded carbon composite structures based on surface control of agricultural waste.

Dual modification of BiVO4 photoanode by enriching bulk and surface oxygen vacancies for enhanced photoelectrochemical performance.

The introduction of oxygen vacancies (Ov) into photoanodes has been considered an effective method to enhance the photoelectrochemical (PEC) water splitting performance. The efficiency of water splitting is related to light absorption, charge separation to the electrode surface, and charge injection into the electrolyte. However, introducing Ov from a single level cannot meet the above objectives. In this work, we present the fabrication of BiVO4 (BVO) photoanodes with bulk and surface Ov, and their respective roles in the PEC performance have been studied. The bulk OV of the photoanode could increase the carrier density and improve the separation efficiency of photogenerated electrons and holes. The surface Ov provide abundant surface active sites, and enhance the charge injection efficiency. Charge separation efficiency of the nitrogen-treated BVO (N:BVO) (69.1 % at 0.75 V vs RHE and 85.1 % at 1.23 V vs RHE) has a noticeable increase compared with that of BVO (51.2 % at 0.75 V vs RHE and 64.6 % at 1.23 V vs RHE), nevertheless, only a minor enhancement of charge injection efficiency (from 49.1 % to 56.5 % at 1.23 V vs RHE). After the deposition of NiFeOOH, the photoanodes present superior charges injection efficiency in the whole range of applied potential. The as-synthesized N:BVO/U-NiFeOOH photoanode exhibits a photocurrent density of 5.52 mA·cm-2 at 1.23 V vs RHE with a 97 % Faradaic efficiency for O2/H2 evolution. Thus, there is a synergistic effect between the bulk OV and surface OV on the BVO photoanode, exhibiting highly promoted PEC water splitting activity relative to the individual OV decorated BVO for oxygen evolution reaction, which provides a promising strategy for fabricating efficient solar water splitting systems.

Semiconductor-metal-semiconductor TiO2@Au/g-C3N4 interfacial heterojunction for high performance Z-scheme photocatalyst.

We designed an edge-sites 2D/0D/2D based TiO2@Au/g-C3N4 Z-scheme photocatalytic system consists of highly exposed (001) TNSs@Au edge-site heterojunction, and the Au/g-C3N4 interfacial heterojunction. The designed photocatalyst was prepared by a facile and controlled hydrothermal synthesis strategy via in-situ nanoclusters-to-nanoparticles deposition technique and programable calcination in N2 atmosphere to get edge-site well-crystalline interface, followed by chemically bonded thin overlay of g-C3N4. Photocatalytic performance of the prepared TNSs@Au/g-C3N4 catalyst was evaluated by the photocatalytic degradation of organic pollutants in water under visible light irradiation. The results obtained from structural and chemical characterization conclude that the inter-facet junction between highly exposed (001) and (101) TNSs surface, and TNSs@Au interfacial heterojunction formed by a direct contact between highly crystalline TNSs and Au, are the key factors to enhance the separation efficiency of photogenerated electrons/holes. On coupling with overlay of g-C3N4 2D NSs synergistically offer tremendous reactive sites for the potential photocatalytic dye degradation in the Z-scheme photocatalyst. Particularly in the designed photocatalyst, Au nanoparticles accumulates and transfer the photo-stimulated electrons originated from anatase TNSs to g-C3N4 via semiconductor-metal heterojunction. Because of the large exposed reactive 2D surface, overlay g-C3N4 sheets not only trap photoelectrons, but also provide a potential platform for increased adsorption capacities for organic contaminants. This work establishes a foundation for the development of high-performance Z-scheme photocatalytic systems.

Preparation of Ag3PO4/α-Fe2O3 hybrid powders and their visible light catalytic performances.

The inefficiency of conventional photocatalytic treatment for removing rhodamine B is posing potential risks to ecological environments. Here, we construct a highly efficient photocatalyst consisting of Ag3PO4 and α-Fe2O3 hybrid powders for the treatment of rhodamine B. Ag3PO4 nanoparticles (nanoparticles, about 50 nm) are uniformly dispersed on the surface of α-Fe2O3 microcrystals (hexagonal sheet, about 1.5 µm). The Ag3PO4-deposited uniformity on the α-Fe2O3 surface first increased, then decreased on increasing the hybrid ratio of Ag3PO4 to α-Fe2O3. When the hybrid ratio of Ag3PO4 to α-Fe2O3 is 1 : 2, the distribution of Ag3PO4 particles on the sheet α-Fe2O3 is more uniform with excellent Ag3PO4/α-Fe2O3 interface performance. The catalytic degradation efficiency of hybrids with the introduction of Ag3PO4 nanoparticles on the α-Fe2O3 surface reached 95%. More importantly, the hybrid material exhibits superior photocatalytic stability. Ag3PO4/α-Fe2O3 hybrids have good reusability, and the photocatalytic efficiency could still reach 72% after four reuses. The excellent photocatalytic activity of the as-prepared hybrids can be attributed to the heterostructure between Ag3PO4 and α-Fe2O3, which can effectively inhibit the photoelectron-hole recombination and broaden the visible light response range.

Building core-shell FeSe2@C anode electrode for delivering superior potassium-ion batteries.

Inferior electrical conductivity and large volume variation are two disadvantages of metal selenides. In this work, we have designed a core-shell structure of FeSe2@C composite with low cost using facile hydrothermal method. The FeSe2particles as the 'core' and the carbon layer as the 'shell' displayed good synergistic effect that attributed to alleviate volume expansion of electrode and improving the electrical conductivity, which achieved the fast potassium storage. The core-shell structural FeSe2@C electrode achieved 286 mA h g-1at 1 A g-1over 1000 cycles with 99.8% coulombic efficiency and delivered excellent rate capacity with 273 mA h g-1at 2 A g-1, which was ascribed to dispersed FeSe2particles and the strong carbon shell coating. This work will provide the basis for the further development of the application of metal selenides in the field of flexible electrodes.

A superficial sulfur interfacial control strategy for the fabrication of a sulfur/carbon composite for potassium-sulfur batteries.

Potassium-sulfur batteries in carbonate-based electrolytes cannot work well due to side reactions between polysulfide ions and ester molecules. Currently, removing superficial sulfur is an effective way to solve this issue. Here, we successfully achieved the deep encapsulation of sulfur and removal of superficial sulfur by a simple filtration-washing approach. As expected, the obtained products exhibited improved electrochemical stability and are promising candidates for better potassium-sulfur batteries.

N/S-Co-Doped Porous Carbon Sheets Derived from Bagasse as High-Performance Anode Materials for Sodium-Ion Batteries.

Heteroatom doping is considered to be an efficient strategy to improve the electrochemical performance of carbon-based anode materials for Na-ion batteries (SIBs), due to the introduction of an unbalanced electron atmosphere and increased electrochemical reactive sites of carbon. However, developing green and low-cost approaches to synthesize heteroatom dual-doped carbon with an appropriate porous structure, is still challenging. Here, N/S-co-doped porous carbon sheets, with a main pore size, in the range 1.8-10 nm, has been fabricated through a simple thermal treatment method, using KOH-treated waste bagasse, as a carbon source, and thiourea, as the N and S precursor. The N/S-co-doped carbon sheet electrodes possess significant defects, high specific surface area, enhanced electronic conductivity, improved sodium storage capacity, and long-term cyclability, thereby delivering a high capacity of 223 mA h g-1 at 0.2 A g-1 after 500 cycles and retaining 155 mA h g-1 at 1 A g-1 for 2000 cycles. This work provides a low-cost route to fabricate high-performance dual-doped porous carbonaceous anode materials for SIBs.

Easily controllable synthesis of alpha-MoO3 nanobelts and MoO2 microaxletrees through one-pot hydrothermal route.

A mild one-pot hydrothermal route has been successfully designed to controllably prepare orthorhombic alpha-MoO3 nanobelts and monoclinic MoO2 microaxletrees respectively by adjusting the dosage of (NH4)6M07O24 x 4H2O (AHM). The products are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and UV-visible absorption spectrum. The as-prepared alpha-MoO3 nanobelts, with widths of 100-400 nm and lengths up to 30-40 microm, grow along [001] direction. The as-obtained MoO2 microaxletrees are assembled by countless nanolaths with the thickness of 80-150 nm. The chemical reaction processes for the formation of MoO(x) (MoO3 and MoO2) phases are investigated based on the experimental phenomena. The possible growth mechanisms are also discussed. The band gap energies (E(g)) of the obtained alpha-MoO3 nanobelts and MoO2 microaxletrees are calculated to be 2.90 and 3.72 eV, respectively. This work exhibits an effective approach in the selectively controlled synthesis of MoO(x) (x = 2, 3) nanomaterials via one-step hydrothermal strategy.

Facile sonochemical synthesis of hierarchical porous CuO nanotablets.

Hierarchical semiconductor CuO nanotablets with pores have been fabricated on a large scale by a facile and one-pot sonochemical process using the copper acetate and ammonia aqueous solution as precursor in the absence of surfactants or additives. The as-synthesized products were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), and N2 physisorption. The results reveal that porous tablet-shaped CuO nanostructures composed of nanoribbons possess a monoclinc phase CuO with the average diameters about 200 nm and around 50 nm in thickness. The Brunnauer-Emmett-Teller (BET) specific surface area and the single point adsorption total pore volume were measured to be 26.8 m2/g and 0.083 cm3/g, respectively. The band-gap energies were estimated to be 2.52 eV from a UV-vis absorption spectrum, which showed the quantum size effects of the nanosized semiconductors. A possible mechanism for porous CuO nanotablets was discussed.

One-pot sonochemical fabrication of hierarchical hollow CuO submicrospheres.

Hierarchical hollow CuO submicrospheres have been fabricated on a large scale by a facile one-pot sonochemical process in the absence of surfactants and additives. The as-prepared products were investigated by XRD, FESEM, EDX, TEM, SAED, HRTEM and BET nitrogen adsorption-desorption isotherms. The results reveal that hollow pumpkin-shaped structures possess a monoclinic phase CuO with the diameters ranging from 400 to 500 nm, and their walls with around 45 nm in thickness are composed of numerous single crystalline CuO nanoribbons with a width of about 8 nm. The BET specific surface area of the as-synthesized CuO hollow structures was measured to be 59.60 m(2)/g, and the single point adsorption total pore volume was measured to be 0.1036 cm(3)/g. A possible growth mechanism for the formation of hierarchical hollow CuO structures was proposed, which is considered to be a sonohydrolysis - oriented aggregation - Ostwald ripening process. The novel hollow CuO spherical structures may utilize applications in biosensors, photonics, electronics, and catalysts.

[Synthesis, characterization, spectroscopy and theoretical calculation of two novel carbazole derivatives].

Two novel carbazole derivatives, 3-acetyl-9-n-hexylcarbazole (AHCZ) and 3, 6- diacetyl-9-n-hexylcarbazole (DHCZ) were synthesized through Friedel-Crafts reaction. The compounds were characterized by IR spectra, 1H NMR, MS and elemental analysis. UV-visible spectra of AHCZ and DHCZ were measured and compared with those of their precursors, 9-hexylcarbazole(HCZ) and carbazole(CZ). DHCZ and AHCZ exhibited strong absorption band, revealing the extent of pi conjugation in the system. TD-DFT method was performed to analyze the electronic absorption spectra of AHCZ and DHCZ, and the calculated excitation energies and oscillator strengths were compared with the experimental results.