Carbonaceous materials especially the metal‐free carbons have attracted widespread attentions owing to their risk free with metal dissolving during the electrocatalysis process, but their further developments are still hindered by missing a suitable scenario on practical applications. Herein, we demonstrate a successful case of using the oxygen‐containing‐groups modified carbons for the H2O2 electrosynthesis and the derivate electrochemical advanced oxidation process. The active sites with the more C‐O rather than C=O groups are easily obtained by controlling the temperature and time in the wet chemical treatment. Identified by theoretical calculations and electrochemical testing, the modified carbons with the highest ratio of C‐O/C=O groups exhibit the high activity with the above 90% H2O2 selectivity over the entire potential during 2e‐transfer oxygen reduction reaction, attributing to their enlarged charge delocalization. In addition, the corresponding gas diffusion electrodes with the high‐speed and high‐stability H2O2 electrosynthesis (2.78 μg s‐1 cm‐2 with the above 80% current efficiency) are applied for the electro‐peroxone process on the simulant and practical phenolic wastewater, where the chemical oxygen demand removal reaches above 90%. The long‐term operation in the harsh electrochemical environment for over 200 h also confirms its great potential on practical electrochemical applications.
High-precision, non-enzymatic electrochemical detection of glucose is of vital importance for the diagnosis and treatment of diabetes mellitus. To meet this requirement, a facile and effective strategy for creating glucose-sensitive detective materials with high sensitivity and selectivity is demonstrated via the synthesis of Ni nanoparticles self-supported on N-doped carbon (Ni/NC) by direct pyrolysis of cross-linked nickel polyphthalocyanine (NiPPc) for non-enzymatic glucose detection. Owing to the extended electronic structure of the N-doped carbon supports and the considerable improvement in charge/mass transport, the resultant Ni/NC sample exhibits excellent activity and long-term reusability in non-enzymatic glucose detection, with a sensitivity of 660.3 μA mM-1 cm-2 and a rather low detection limit of 0.12 μM, along with a wide linear range of 2 μM to 4.658 mM. The facile and promising synthetic strategy of Ni-based sensors for non-enzymatic glucose detection may offer an advanced alternative to noble metal and enzymatic sensors for the diagnosis of diabetes mellitus, and may promote the development of such materials in medical technology.
Abstract Information security holds paramount importance in the contemporary information society. Here, a novel cryptography method is proposed based on the multi‐wavelength complex‐amplitude metasurface, which can achieve a high security level by generating a frequency‐selective key as an additional layer of protection. Moreover, the quality of the decrypted holographic images can be significantly improved by employing the complex‐amplitude encoding method and the modified visual secret sharing scheme, which adopts a new superposition operator to prevent fidelity loss. As a proof‐of‐concept demonstration, a prototype metasurface sample is designed, fabricated, and characterized, where the measured results agree very well with the numerical ones and the design goals. The proposed method can reinforce security level and improve fidelity of the decrypted message, rendering it appealing for applications in communication and anti‐counterfeiting.
As an important public health problem, osteoporosis (OP) in China is also in an upward trend year by year. As a standard method for diagnosing OP, dual-energy X-ray absorptiometry (DXA) cannot analyze the pathological process but only see the results. It is difficult to evaluate the early diagnosis of OP. Our study was carried out through a serum metabolomic study of OP in Chinese postmenopausal women on untargeted gas chromatography (GC)/liquid chromatography (LC)-mass spectrometry (MS) to find possible diagnostic markers.50 Chinese postmenopausal women with osteoporosis and 50 age-matched women were selected as normal controls. We first used untargeted GC/LC-MS to analyze the serum of these participants and then combined it with a large number of multivariate statistical analyses to analyze the data. Finally, based on a multidimensional analysis of the metabolites, the most critical metabolites were considered to be biomarkers of OP in postmenopausal women. Further, biomarkers identified relevant metabolic pathways, followed by a map of metabolic pathways found in the database.We found that there may be metabolic pathway disorders like glucose metabolism, lipid metabolism, and amino acid metabolism in postmenopausal women with OP. 18 differential metabolites are considered to be potential biomarkers of OP in postmenopausal women which are a major factor in metabolism and bone physiological function.These findings can be applied to clinical work through further validation studies. It also shows that metabonomic analysis has great potential in the application of early diagnosis and recurrence monitoring in postmenopausal OP women.
Abstract Single Fe atoms dispersed on hierarchically structured porous carbon (SA‐Fe‐HPC) frameworks are prepared by pyrolysis of unsubstituted phthalocyanine/iron phthalocyanine complexes confined within micropores of the porous carbon support. The single‐atom Fe catalysts have a well‐defined atomic dispersion of Fe atoms coordinated by N ligands on the 3D hierarchically porous carbon support. These SA‐Fe‐HPC catalysts are comparable to the commercial Pt/C electrode even in acidic electrolytes for oxygen reduction reaction (ORR) in terms of the ORR activity ( E 1/2 =0.81 V), but have better long‐term electrochemical stability (7 mV negative shift after 3000 potential cycles) and fuel selectivity. In alkaline media, the SA‐Fe‐HPC catalysts outperform the commercial Pt/C electrode in ORR activity ( E 1/2 =0.89 V), fuel selectivity, and long‐term stability (1 mV negative shift after 3000 potential cycles). Thus, these nSA‐Fe‐HPCs are promising non‐platinum‐group metal ORR catalysts for fuel‐cell technologies.
Although there have been many efforts to improve the performance of electrical energy storage devices by preparing electrode materials with nanostructures and specific chemical compositions, most of the synthetic pathways developed have not addressed issues of safety, cost, and sustainability. Herein, we have simultaneously realized the sustainable synthesis, nanostructure engineering, and heteroatom doping of two carbon materials by separate tailored strategies using gelatin and phytic acid as biomass precursors. These—together with all the other reagents employed—have high terrestrial abundance with low cost and low toxicity and can be easily mixed at a molecular level in deionized water without using organic solvents. Additionally, all the non-carbonaceous products can be easily removed by water washing and further recycled by heat drying. The tailored syntheses result in porous nanosheet structures and uniform heteroatom doping of the final carbons. Based on their typical porosities and chemical compositions, these two carbons have been specifically used as cathode and anode materials in Na-ion capacitors. Electrochemical characterization and first-principles calculations show that the porous nanosheet structures and heteroatom doping endow the carbon electrodes with battery-capacitive storage features, thus leading to their excellent electrochemical performance in half cells. Beneficial from the compatible kinetics of cathode and anode, the assembled Na-ion capacitor exhibits high energy density (135.3 Wh kg–1) and power density (16.1 kW kg–1) as well as ultralong lifetime (88.6% of the initial capacity after 8000 cycles).
The high power density of fuel cells is attributed to the synergetic effect associated with the superior oxygen reduction reaction (ORR) electrocatalysts and rational cathode structure, which can efficiently enhance the electrochemical process of the sluggish cathodic reaction. On the basis of our previous works about the ORR electrocatalysts of Ni/N-doped carbon-supported Pt nanoparticles, we develop an in situ ultraviolet-induced method to prepare a bi-gradient gas diffusion electrode (GDE) involving gradient Pt deposition (Pt concentrations increasing first and then decreasing from the proton exchange membrane side to the carbon paper side) in the catalyst layer and gradient hydrophobicity (high-hydrophobic side near the catalyst layer and low-hydrophobic side near the gas flow channel) in the gas diffusion layer (g-CL/g-GDL). Owing to the enhancement of the electrochemical process, the bi-gradient g-CL/g-GDL shows superior performance with large power densities compared to the non-gradient or single-gradient GDE. The finite element calculation results demonstrate that the improved performance of g-CL/g-GDL was due to the balance of reactant (oxygen and proton) concentration at the highly reactive region and the rapid departure of products (water) simultaneously.
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