Defect-Induced Nucleation and Epitaxy: A New Strategy toward the Rational Synthesis of WZ-GaN/3C-SiC Core-Shell Heterostructures.

In this work, we demonstrate a new strategy to create WZ-GaN/3C-SiC heterostructure nanowires, which feature controllable morphologies. The latter is realized by exploiting the stacking faults in 3C-SiC as preferential nucleation sites for the growth of WZ-GaN. Initially, cubic SiC nanowires with an average diameter of ∼100 nm, which display periodic stacking fault sections, are synthesized in a chemical vapor deposition (CVD) process to serve as the core of the heterostructure. Subsequently, hexagonal wurtzite-type GaN shells with different shapes are grown on the surface of 3C-SiC wire core. In this context, it is possible to obtain two types of WZ-GaN/3C-SiC heterostructure nanowires by means of carefully controlling the corresponding CVD reactions. Here, the stacking faults, initially formed in 3C-SiC nanowires, play a key role in guiding the epitaxial growth of WZ-GaN as they represent surface areas of the 3C-SiC nanowires that feature a higher surface energy. A dedicated structural analysis of the interfacial region by means of high-resolution transmission electron microscopy (HRTEM) revealed that the disordering of the atom arrangements in the SiC defect area promotes a lattice-matching with respect to the WZ-GaN phase, which results in a preferential nucleation. All WZ-GaN crystal domains exhibit an epitaxial growth on 3C-SiC featuring a crystallographic relationship of [12̅10](WZ-GaN) //[011̅](3C-SiC), (0001)(WZ-GaN)//(111)(3C-SiC), and d(WZ-GaN(0001)) ≈ 2d(3C-SiC(111)). The approach to utilize structural defects of a nanowire core to induce a preferential nucleation of foreign shells generally opens up a number of opportunities for the epitaxial growth of a wide range of semiconductor nanostructures which are otherwise impossible to acquire. Consequently, this concept possesses tremendous potential for the applications of semiconductor heterostructures in various fields such as optics, electrics, electronics, and photocatalysis for energy harvesting and environment processing.

Protecting Li-metal anode with LiF-enriched solid electrolyte interphase derived from a fluorinated graphene additive.

As the holy-grail material, the Li-metal anode has been considered the potential anode of the next generation of Li-metal batteries (LMBs). However, issues of undesirable dendrite growth and unsatisfactory reversibility of the Li-plating/stripping process during the electrochemical cycling impede further application of LMBs. Herein, we innovatively introduce fluorinated graphene (F-Gr) species as a sacrificial effective electrolyte additive into EC/EMC-based electrolyte, which effectively triggers LiF-enriched (composition) and organic/inorganic species uniform-distributed (structure) SEI film architecture that features robustness and denseness, as well as good stability. With the F-Gr additive, efficient Li-metal anode protection (dendrite-free morphology on Li-metal surface and improved Li plating/stripping reversibility during electrochemical cycling) and significantly enhanced long-term lifespan of LMBs is achieved. Remarkably, classical electrochemical techniques, combined with the surface-sensitive characterizations (XPS and TOF-SIMS), comprehensively and systematically highlight critical structure-activity relationships between the SEI architecture (both composition and structure) and electrochemical performance. These techniques provide deep insights into the optimal electrolyte designation of Li-metal anode in LMBs.

A flexible gradient lateral flow immunochromatographic assay for qualitative, semi-quantitative, and quantitative determination of serum amyloid A.

Serum amyloid A (SAA) is an acute-phase protein produced in response to inflammatory proteins during infections, inflammation, trauma, surgery, cancer, and other conditions. Early and accurate detection of SAA is necessary for diagnosis and monitoring of disease progression. To meet this need, we developed a gradient lateral flow immunoassay test strip using Au nanoparticles as signal reporters. The test strip has three test (T1, T2, and T3) lines with progressively decreasing concentrations of SAA antibody, enabling the determination of high, medium, and low concentrations of SAA in serum. The test strip results were analyzed using three distinct readout methods, each with different sensitivity, accuracy, and precision for SAA concentration measurements. Qualitative judgment is based on the color of the T1 line. Semi-quantitative assessment of SAA concentration is determined by the number of colored T-lines. Specifically, color development in T1 line alone indicates a concentration range of 10-50 µg/mL, while T1 and T2 lines together indicate a range of 50-100 µg/mL, and development in all three lines (T1, T2, and T3) indicates a concentration of >100 µg/mL. Quantitative analysis was performed using either smartphone imaging or image scanning with ImageJ software. By using a five-parameter logistic function, we found a strong correlation (R2 = 0.998) between the ratio of signal intensities of (T1 + T2 + T3) to the control (C) line and SAA concentrations ranging from 5 to 1000 µg/mL. At lower concentrations (0-100 µg/mL), we observed a proportional relationship between the value of (T1 + T2 + T3)/C and SAA concentration. The limit of detection for SAA was 9.33 ng/mL (or 6.53 µg/mL of SAA in undiluted serum samples) for the smartphone method and 3.06 ng/mL (or 2.14 µg/mL of SAA in undiluted serum samples) for the scanner method. The gradient test strip was highly consistent with a commercially available SAA immunochromatographic test strip when tested with real human serum samples. Passing-Bablok regression indicated that results obtained using the smartphone app and scanner methods of the gradient test strip were comparable to those obtained using the commercial test strip. The gradient test strip is flexible and adaptable, providing solutions for qualitative, semi-quantitative, and quantitative SAA measurements.

Protecting Li-metal in O2 atmosphere by a sacrificial polymer additive in Li-O2 batteries.

Li-O2 batteries (LOBs) with Li-metal as the anode are characterized by their high theoretical energy density of 3500 W h kg-1 and are thus considered next-generation batteries with an unlimited potential. However, upon cycling in a harsh O2 atmosphere, the poor-quality solid electrolyte interphase (SEI) film formed on the surface of the Li-metal anode cannot effectively suppress the shuttle effect from O2, superoxide species, protons, and soluble side products. These issues lead to aggravated Li-metal corrosion and hinder the practical development of LOBs. In this work, a polyacrylamide-co-polymethyl acrylate (PAMMA) copolymer was innovatively introduced in an ether-based electrolyte as a sacrificial additive. PAMMA was found to preferentially decompose and promote the formation of a dense and Li3N-rich SEI film on the Li-metal surface, which could effectively prohibit the shuttle effect from a series of detrimental species in the Li-O2 cell during the discharge/charge process. Using PAMMA, well-protected Li-metal in a harsh O2 atmosphere and significantly enhanced cycling performance of the Li-O2 cell could be achieved. Thus, the use of a sacrificial polymer additive provides a promising strategy for the effective protection of Li-metal in Li-O2 cells in a severe O2 atmosphere during practical applications.

Correction: State-of-the-art advancements of atomically thin two-dimensional photocatalysts for energy conversion.

Correction for 'State-of-the-art advancements of atomically thin two-dimensional photocatalysts for energy conversion' by Wa Gao et al., Chem. Commun., 2022, 58, 9594-9613, https://doi.org/10.1039/D2CC02708A.

State-of-the-art advancements of atomically thin two-dimensional photocatalysts for energy conversion.

Excessive use of fossil fuels leads to energy shortages and environmental pollution, threatening human health and social development. As a clean, green, and sustainable technology, generation of renewable energy from solar light through photocatalysis has received increasing attention to cope with the impending energy and environmental crisis. The atomically thin two-dimensional (2D) semiconductors with large surface area and abundant low-coordinate surface atoms prove to exhibit enormous potential to attain efficient photocatalytic performance. These 2D ultrathin materials can shorten the transport distance of charge carriers from the interior to the surface, enhance reactants' (e.g. CO2 and H2O) adsorption and activation to lower the energy barrier, promote specific reaction processes and inhibit competitive reactions, and regulate the efficiency and selectivity of the catalytic reaction. This Feature article provides a concise overview of the preparation, catalytic mechanism, strategies for boosting the photoconversion performance, various photocatalytic applications, and characterization techniques of atomically thin 2D semiconductors. The major challenges and opportunities of the ultrathin photocatalysts are also addressed. It is hoped that this review can provide useful guidelines toward further research on 2D nanocatalysts, and inspire practical applications of these unique materials for energy conversion.

A hybrid GaN/Ga2O3 structure anchored on carbon cloth as a high-performance electrode of supercapacitors.

A hybrid structure of GaN/Ga2O3 microrods was fabricated on carbon cloth (CC) using a hydrothermal process combined with a high-temperature nitridation followed by an air annealing process. By elevating the post-annealing temperature to 500 °C, both electron density (ND) and specific capacitance (Ca) of the composite electrode were significantly enhanced. Symmetric SCs assembled with GaN/CC-500 showed great potential in both 1 M H2SO4 aqueous solution and a PVA-H2SO4 gel-like electrolyte. The aqueous symmetric GaN/CC-500 SC exhibited an excellent capacitance (1301.20 mF cm-2, 0.5 mA cm-2), high rate capability (75.23% of capacitance retention at 10 mA cm-2), outstanding cycling stability (77.27% of capacitance retention after 20 000 cycles, 10 mA cm-2), and large energy storage capability (27.53 µW h cm-2 of energy density, 0.10 mW cm-2 of power density). All-solid-state symmetric GaN/CC-500 SC also manifested a high capacitance (1183.35 mF cm-2, 0.5 mA cm-2) and good rate capability (53.98% capacitance retention, 10 mA cm-2). The high electrochemical performance of the GaN/CC-500 electrode is attributed to the GaN/Ga2O3 hybrid structure, with α-Ga2O3 providing absorption/redox active sites on the surface, and the heavily oxygen-doped GaN enabling fast electron transport. The microrods with the GaN/Ga2O3 hybrid structure as the active material for solid SCs can deliver an energy density of 0.58 W h kg-1 (3.54 mW h cm-3) with a power density of 154 W kg-1 (0.94 W cm-3). The mechanism identified in this work would be helpful in designing GaN-based energy storage devices with better performances in the future.

Correction: A hybrid GaN/Ga2O3 structure anchored on carbon cloth as a high-performance electrode of supercapacitors.

Correction for 'A hybrid GaN/Ga2O3 structure anchored on carbon cloth as a high-performance electrode of supercapacitors' by Yan-Ling Hu, et al., Dalton Trans., 2022, https://doi.org/10.1039/d2dt02904a.

Microwave-Hydrothermal Treated Grape Peel as an Efficient Biosorbent for Methylene Blue Removal.

Biosorption using agricultural wastes has been proven as a low cost and efficient way for wastewater treatment. Herein, grape peel treated by microwave- and conventional-hydrothermal processes was used as low cost biosorbent to remove methylene blue (MB) from aqueous solutions. The adsorption parameters including the initial pH value, dosage of biosorbents, contact time, and initial MB concentration were investigated to find the optimum adsorption conditions. The biosorbent obtained by microwave-hydrothermal treatment only for 3 min at 180 °C (microwave-hydrothermal treated grape peel, MGP) showed faster kinetics and higher adsorption capability than that produced by a conventional-hydrothermal process (hydrothermal treated grape peel, HGP) with a duration time of 16 h. The maximum adsorption capability of MGP under the optimum conditions (pH = 11, a dosage of 2.50 g/L) as determined with the Langmuir model reached 215.7 mg/g, which was among the best values achieved so far on biosorbents. These results demonstrated that the grape peel treated by a quick microwave-hydrothermal process can be a very promising low cost and efficient biosorbent for organic dye removal from aqueous solutions.

3D-branched hierarchical 3C-SiC/ZnO heterostructures for high-performance photodetectors.

The ultra-sensitive photodetection of different wavelengths holds promising applications in high-performance optoelectronic devices and it requires an efficient and suitable semiconductor unit. Herein, we demonstrated the designable synthesis of 3D-branched hierarchical 3C-SiC/ZnO heterostructures by a three-step process and their assembling into an ultrasensitive photodetector. Microstructure analyses using high-resolution transmission electron microscopy reveal that the hierarchical 3C-SiC/ZnO heterostructure is composed of single-crystal 3C-SiC nanowires as a central stem and numerous well-aligned single-crystalline ZnO nanorods as branch shells. Optoelectronic tests on the 3C-SiC/ZnO heterostructure photodetector verify the outstanding photo-detection performance with an ultrahigh EQE (1.69 × 108%), a superior photoresponsivity (4.8 × 105 A W-1), a very fast response time (a rise time of 40 ms and a decay time of 60 ms), a high photo-dark current ratio of 187.8 and an excellent photocurrent stability and reproducibility, which is significantly advantageous or comparable to those of ZnO and other inorganic semiconductor nanostructure based photodetectors. To understand the excellent photodetection of hierarchical 3C-SiC/ZnO heterostructures, a band-gap energy diagram describing the photogenerated electron transport process is plotted and the corresponding mechanism is discussed. The strategy proposed in the present work will open up more opportunities for the design and boost of ultra-sensitive photodetectors based on semiconductor heterostructures.