Manipulating the active species and improving the structural stabilization of sulfur‐containing catalysts during the OER process remain a tremendous challenge. Herein, we constructed NiO/NiS2 and ...Fe−NiO/NiS2 as catalyst models to study the effect of Fe doping. As expected, Fe−NiO/NiS2 exhibits a low overpotential of 270 mV at 10 mA cm−2. The accumulation of hydroxyl groups on the surface of materials after Fe doping can promote the formation of highly active NiOOH at a lower OER potential. Moreover, we investigated the level of corrosion of M−S bonds and compared the stability variation of M−S bonds with Fe at different locations. Interestingly, Fe bonded with S in the bulk as the sacrificial agent can alleviate the oxidation corrosion of partial Ni−S bonds and thus endow Fe−NiO/NiS2 long‐term durability. This work could motivate the community to focus more on resolving the corrosion of sulfur‐containing materials.
Bulk doped Fe not only accelerates the surface reconstruction of NiO/NiS2 into the active NiOOH phase at a lower oxygen evolution reaction (OER) overpotential but also alleviates the oxidation corrosion of partial Ni−S bonds to provide a promising way to balance the activity and stability of sulfur‐containing materials in the OER process.
The hydrogen evolution reaction (HER) usually has sluggish kinetics in alkaline solution due to the difficulty in forming binding protons. Herein we report an electrocatalyst in which sulfur atoms ...are doping in the oxygen vacancies (VO) of inverse spinel NiFe2O4 (S‐NiFe2O4) to create active sites with enhanced electron transfer capability. This electrocatalyst has an ultralow overpotential of 61 mV at the current density of 10 mA cm−2 and long‐term stability of 60 h at 1.0 Acm−2 in 1.0 M KOH media. In situ Raman spectroscopy revealed that S sites adsorb hydrogen adatom (H*) and in situ form S‐H*, which favor the production of hydrogen and boosts HER in alkaline solution. DFT calculations further verified that S introduction lowered the energy barrier of H2O dissociation. Both experimental and theoretical investigations confirmed S atoms are active sites of the S‐NiFe2O4.
Sulfur‐atom doping of inverse spinel NiFe2O4 results in the occupation of the oxygen vacancies. S sites in the S‐NiFe2O4 likely adsorb H adatoms and form S‐H* in situ, which boosts the hydrogen evolution reaction (HER) in alkaline solution. DFT calculations further verified that the lowered energy barrier for H2O dissociation induced by S doping is the key reason for the remarkable HER performance.
Structural engineering and compositional controlling are extensively applied in rationally designing and fabricating advanced freestanding electrocatalysts. The key relationship between the spatial ...distribution of components and enhanced electrocatalysis performance still needs further elaborate elucidation. Here, CeO2 substrate supported CoS1.97 (CeO2‐CoS1.97) and CoS1.97 with CeO2 surface decorated (CoS1.97‐CeO2) materials are constructed to comprehensively investigate the origin of spatial architectures for the oxygen evolution reaction (OER). CeO2‐CoS1.97 exhibits a low overpotential of 264 mV at 10 mA cm−2 due to the stable heterostructure and faster mass transfer. Meanwhile, CoS1.97‐CeO2 has a smaller Tafel slope of 49 mV dec−1 through enhanced adsorption of OH−, fast electron transfer, and in situ formation of Co(IV)O2 species under the OER condition. Furthermore, operando spectroscopic characterizations combined with theoretical calculations demonstrate that spatial architectures play a distinguished role in modulating the electronic structure and promoting the reconstruction from sulfide to oxyhydroxide toward higher chemical valence. The findings highlight spatial architectures and surface reconstruction in designing advanced electrocatalytic materials.
Two novel CeO2/CoS1.97 heterostructure electrocatalysts (CeO2‐CoS1.97 and CoS1.97‐CeO2) are constructed to investigate the relationships between spatial architectures and oxygen evolution reaction (OER) performances, where different configuration endows hybrids with distinct intermediate adsorption, modulated electronic structures, and promoted electrochemical reconstruction, thus improving the OER kinetics and performances. This work sheds light on the importance of rational design and synthesis of advanced hybrid electrocatalysts with functional spatial architectures.
Graphene Platform for Sensing Biomolecules Lu, Chun-Hua; Yang, Huang-Hao; Zhu, Chun-Ling ...
Angewandte Chemie (International ed.),
June 15, 2009, Volume:
48, Issue:
26
Journal Article
Peer reviewed
Sensitive platform: The use of graphene oxide (GO) as a platform for the sensitive and selective detection of DNA and proteins is presented. The interaction of GO and dye-labeled single-stranded DNA ...leads to quenching of the dye fluorescence. Conversely, the presence of a target DNA or protein leads to the binding of the dye-labeled DNA and target, releasing the DNA from GO, thereby restoring the dye fluorescence (see picture).
The oxygen reduction reaction (ORR) has been demonstrated as a critical technology for both energy conversion technologies and hydrogen peroxide intermediate production. Herein, an in situ oxygen ...evolution reaction (OER) surface evolution strategy is applied for changing the surface structure of MnCo2O4 oxide with tetrahedral and octahedral cations vacancies to realize reaction pathway switching from 2e− ORR and 4e− ORR. Interestingly, the as‐synthesized MnCo2O4‐pristine (MnCo2O4‐P) with the highest surficial Mn/Co octahedron occupation favors two electrons reaction routes exhibiting high H2O2 selectivity (≈80% and reaches nearly 100% at 0.75 V vs RHE); after surface atoms reconstruction, MnCo2O4‐activation (MnCo2O4‐A) with the largest Mn/Co tetrahedron occupation present excellent ORR performance through the four‐electron pathway with an ultrahigh onset potential and half‐wave potential of 0.78 and 0.92 V, ideal mass activity (MA), and turnover frequencies (TOF) values. Density functional theory (DFT) calculations reveal the concurrent modulations of both Co and Mn by the surface reconstructions, which improve the electroactivity of MnCo2O4‐A toward the 4e− pathway. This work provides a new perspective to building correlation of OER activation–ORR property, bringing detailed understating for reaction route transformation, and thus guiding the development of certain electrocatalysts with specific purposes.
The oxygen reduction reaction (ORR) is crucial for both energy conversion technologies and hydrogen peroxide intermediate production, which proceeds via four‐electron or two‐electron pathways, respectively. Special electrocatalysts to promote either the 4e− or the 2e− reaction route are important. The surficial metals occupation of partially inverse MnCo2O4 can be tuned to realize this reaction mechanism switching.
Graphitic carbon nitrides (g‐C3N4) are a class of 2D polymeric materials mainly composed of carbon and nitrogen atoms. g‐C3N4 are attracting dramatically increasing interest in the areas of sensing, ...imaging, and therapy, due to their unique optical and electronic properties. Here, the luminescent properties (mainly includes photoluminescence and electrochemiluminescence), and catalytic and photoelectronic properties related to sensing and therapy applications of g‐C3N4 materials are reviewed. Furthermore, the fabrication and advantages of sensing, imaging and therapy systems based on g‐C3N4 materials are summarized. Finally, the future perspectives for developing the sensing, imaging and therapy applications of the g‐C3N4 materials are discussed.
The sensing, imaging and therapy applications of g‐C3N4 materials are summarized. The luminescent, catalytic and photoelectronic properties and mechanisms of g‐C3N4 materials related to sensing and therapy applications are introduced and discussed. The principles and advantages of the sensing, imaging and therapy systems are concluded.
Hydrogels are crosslinked hydrophilic polymers that can absorb a large amount of water. By their hydrophilic, biocompatible and highly tunable nature, hydrogels can be tailored for applications in ...bioanalysis and biomedicine. Of particular interest are DNA-based hydrogels owing to the unique features of nucleic acids. Since the discovery of the DNA double helical structure, interest in DNA has expanded beyond its genetic role to applications in nanotechnology and materials science. In particular, DNA-based hydrogels present such remarkable features as stability, flexibility, precise programmability, stimuli-responsive DNA conformations, facile synthesis and modification. Moreover, functional nucleic acids (FNAs) have allowed the construction of hydrogels based on aptamers, DNAzymes, i-motif nanostructures, siRNAs and CpG oligodeoxynucleotides to provide additional molecular recognition, catalytic activities and therapeutic potential, making them key players in biological analysis and biomedical applications. To date, a variety of applications have been demonstrated with FNA-based hydrogels, including biosensing, environmental analysis, controlled drug release, cell adhesion and targeted cancer therapy. In this review, we focus on advances in the development of FNA-based hydrogels, which have fully incorporated both the unique features of FNAs and DNA-based hydrogels. We first introduce different strategies for constructing DNA-based hydrogels. Subsequently, various types of FNAs and the most recent developments of FNA-based hydrogels for bioanalytical and biomedical applications are described with some selected examples. Finally, the review provides an insight into the remaining challenges and future perspectives of FNA-based hydrogels.
We survey advances in bioanalytical and biomedical applications of functional nucleic acid-based hydrogels in this review.
Studies have explored the influence of DNA damage in assisted reproductive technology (ART), but the outcome remains controversial. To determine whether sperm DNA fragmentation index (DFI) has any ...effect on ART outcomes, we collected detailed data regarding 1,333 IVF cycles performed at our centre, and the data of our retrospective cohort study were extracted for this meta‐analysis. We searched PubMed, Web of Science, EMBASE and Google Scholar and performed a systemic review and meta‐analysis. Primary meta‐analysis of 10 studies comprising 1,785 couples showed that live birth rate was no significantly different between low‐DFI group and high‐DFI group (p > 0.05). Secondary meta‐analysis of 25 studies comprising 3,992 couples showed a higher miscarriage rate in high‐DFI group than in low‐DFI group (RR=1.57 1.18, 2.09, p < 0.01). Meta‐analysis of eight studies comprising 17,879 embryos revealed a lower good‐quality embryo rate (RR=0.65 0.62, 0.68, p < 0.01). Meta‐analysis of 23 studies comprising 6,771 cycles showed that the high‐DFI group had a lower clinical pregnancy rate than low‐DFI group (RR=0.85 0.75, 0.96, p < 0.01). Heterogeneity of included studies weakened our conclusions. Our study showed that DFI has adverse effects on ART outcome. More well‐designed studies exploring the association between DFI and ART outcome are desired.
Quantum memories are essential for quantum information processing. Techniques have been developed for quantum memory based on atomic ensembles. The atomic memories through optical resonance usually ...suffer from the narrow-band limitation. The far off-resonant Raman process is a promising candidate for atomic memories due to broad bandwidths and high speeds. However, to date, the low memory efficiency remains an unsolved bottleneck. Here, we demonstrate a high-performance atomic Raman memory in
Rb vapour with the development of an optimal control technique. A memory efficiency of above 82.0% for 6 ns~20 ns optical pulses is achieved. In particular, an unconditional fidelity of up to 98.0%, significantly exceeding the no-cloning limit, is obtained with the tomography reconstruction for a single-photon level coherent input. Our work marks an important advance of atomic memory towards practical applications in quantum information processing.
Realizing the rational design of perovskite oxides with controllable compositions and nanostructures remains a tremendous challenge for the development of efficient electrocatalysts. Herein, a ...ligand‐assisted synthetic strategy to fabricate perovskite oxides LaCo1−xFexO3 with yolk‐shell nanostructures is developed. Benefiting from the unique structural and compositional merits, LaCo0.75Fe0.25O3 exhibits an overpotential of 310 mV at a current density of 10 mA cm−2 and long‐term stability of 100 h for the oxygen evolution reaction. In situ Raman spectroscopy demonstrates that Fe substitution facilitates the pre‐oxidation of Co sites and induces the surface reconstruction into active Co oxyhydroxides at a relatively lower applied potential, guaranteeing excellent catalytic performances. Density functional theory calculations unravel that the appropriate introduction of Fe into perovskite LaCoO3 leads to the improved electroactivity and durability of the catalyst for the oxygen evolution reaction (OER). Fe‐3d orbitals show a pinning effect on Co‐3d orbitals to maintain the stable valence state of Co sites at the low overpotential of the OER. Furthermore, Zn–air batteries (ZABs) assembled with LaCo0.75Fe0.25O3 display a high open circuit potential of 1.47 V, superior energy density of 905 Wh kg−1 Zn, and excellent stability in a large temperature range. This work supplies novel insights into the future developments of perovskite‐based electrocatalysts.
The general ligand‐assisted strategy of constructing yolk‐shell nanostructures is achieved for a series of perovskite oxides LaCo1−xFexO3. Structural optimization at the micrometer level and electronic modulation at the atomic level boost the oxygen evolution reaction performance of LaCo0.75Fe0.25O3.
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