Degradation and regeneration of Fe-N active sites for the oxygen reduction reaction: the role of surface oxidation, Fe demetallation and local carbon microporosity.

The severe degradation of Fe-N-C electrocatalysts during a long-term oxygen reduction reaction (ORR) has become a major obstacle for application in proton-exchange membrane fuel cells. Understanding the degradation mechanism and regeneration of aged Fe-N-C catalysts would be of particular interest for extending their service life. Herein, we show that the by-product hydrogen peroxide during the ORR not only results in the oxidation of the carbon surface but also causes the demetallation of Fe active sites.

Sb nanosheet modified separator for Li-S batteries with excellent electrochemical performance.

An air-stable antimony (Sb) nanosheet modified separator (SbNs/separator) has been prepared by coating exfoliated Sb nanosheets (SbNs) successfully onto a pristine separator through a vacuum infiltration method. The as-prepared Li-S batteries using SbNs/separators exhibit much improved electrochemical performance compared to the ones using commercial separators. The coulombic efficiency (CE) of the Li-S battery using the SbNs/separator after the initial cycle is close to 100% at a current density of 0.

A biotin-guided hydrogen sulfide fluorescent probe and its application in living cell imaging.

Hydrogen sulfide (HS), a well-known signaling molecule, exerts significant regulatory effects on the cardiovascular and nervous systems. Therefore, monitoring the metabolism of HS offers a potential mechanism to detect various diseases. In addition, biotin is significantly used as a targeting group to detect cancer cells exclusively.

Unveiling the Axial Hydroxyl Ligand on Fe-N-C Electrocatalysts and Its Impact on the pH-Dependent Oxygen Reduction Activities and Poisoning Kinetics.

Fe-N-C materials have shown a promising nonprecious oxygen reduction reaction (ORR) electrocatalyst yet their active site structure remains elusive. Several previous works suggest the existence of a mysterious axial ligand on the Fe center, which, however, is still unclarified. In this study, the mysterious axial ligand is identified as a hydroxyl ligand on the Fe centers and selectively promotes the ORR activities depending on different Fe-N-C configurations, on which the adsorption free energy of the hydroxyl ligand also differs greatly.

Poly(fluorenone--thiophene)-based nanoparticles for two-photon fluorescence imaging in living cells and tissues.

Conjugate polymer nanoparticles (CPNs) were constructed based on poly(fluorenone--thiophenes) (PFOTs) synthesized through a direct arylation polymerization (DArP) approach. Results demonstrate that the developed novel CPNs have potential applications in two-photon fluorescence imaging of both cells and tissues.

Progress and Perspective of Ceramic/Polymer Composite Solid Electrolytes for Lithium Batteries.

Solid composite electrolytes (SCEs) that combine the advantages of solid polymer electrolytes (SPEs) and inorganic ceramic electrolytes (ICEs) present acceptable ionic conductivity, high mechanical strength, and favorable interfacial contact with electrodes, which greatly improve the electrochemical performance of all-solid-state batteries compared to single SPEs and ICEs. However, there are many challenges to overcome before the practical application of SCEs, including the low ionic conductivity less than 10 S cm at ambient temperature, poor interfacial stability, and high interfacial resistance, which greatly restrict the room temperature performance. Herein, the advances of SCEs applied in all-solid-state lithium batteries are presented, including the Li ion migration mechanism of SCEs, the strategies to enhance the ionic conductivity of SCEs by various morphologies of ICEs, and construction methods of the low resistance and stable interfaces of SCEs with both cathode and anode.

MoS/carbon composites prepared by ball-milling and pyrolysis for the high-rate and stable anode of lithium ion capacitors.

Lithium ion capacitors (LICs), bridging the advantages of batteries and electrochemical capacitors, are regarded as one of the most promising energy storage devices. Nevertheless, it is always limited by the anodes that accompany with low capacity and poor rate performance. Here, we develop a versatile and scalable method including ball-milling and pyrolysis to synthesize exfoliated MoS supported by N-doped carbon matrix derived from chitosan, which is encapsulated by pitch-derived carbon shells (MoS/CP).

An aptasensor based on the microscopic enumeration of encoding gold nanoparticles for the detection of C-reactive protein.

C-reactive protein (CRP) is a crucial clinical biomarker for inflammatory and cardiovascular diseases. Therefore, the sensitive, selective and convenient detection of CRP is of great significance. Using gold nanoparticles (AuNPs) and combining the specific interaction between an aptamer and CRP, we developed a simple and convenient assay for CRP detection.

CVD controlled growth of large-scale WS monolayers.

Monolayer tungsten disulfide (WS) with a direct band gap of 2.0 eV and stable properties has been a hotspot in two-dimensional (2D) nanoelectronics and optoelectronics. However, it remains challenging to successfully prepare monolayer WS.

Facile metal-free reduction-based synthesis of pristine and cation-doped conductive mayenite.

In the present study we synthesized conductive nanoscale [CaAlO](4e) (hereafter denoted as CA:e) material, and reduced graphene oxide (rGO) was produced, which was unexpected; graphene oxide was removed after melting the sample. The conductivity of CA:e composites synthesized at 1550 °C was 1.25 S cm, and the electron concentration was 5.

White light-induced cell apoptosis by a conjugated polyelectrolyte through singlet oxygen generation.

A cationic conjugated polyelectrolyte (CPE) PPET3 with a poly(-phenylene ethynylene terthiophene) backbone and quaternary ammonium side chains was designed and synthesized. It serves as an efficient photosensitizer for photodynamic therapy under white light irradiation and induces cell death through the mitochondrial apoptosis pathway.

A Facile Surface Reconstruction Mechanism toward Better Electrochemical Performance of LiTiO in Lithium-Ion Battery.

Through a facile sodium sulfide (NaS)-assisted hydrothermal treatment, clean and nondefective surfaces are constructed on micrometer-sized LiTiO particles. The remarkable improvement of surface quality shows a higher first cycle Coulombic efficiency (≈95%), a significantly enhanced cycling performance, and a better rate capability in electrochemical measurements. A combined study of Raman spectroscopy and inductive coupled plasma emission spectroscopy reveals that the evolution of LiTiO surface in a water-based hydrothermal environment is a hydrolysis-recrystallization process, which can introduce a new phase of anatase-TiO.

High-Density Microporous LiTiO Microbars with Superior Rate Performance for Lithium-Ion Batteries.

Nanosized LiTiO (LTO) materials enabling high rate performance suffer from a large specific surface area and low tap density lowering the cycle life and practical energy density. Microsized LTO materials have high density which generally compromises their rate capability. Aiming at combining the favorable nano and micro size properties, a facile method to synthesize LTO microbars with micropores created by ammonium bicarbonate (NHHCO) as a template is presented.