Highly active oxygen evolution reaction model electrode based on supported gas-phase NiFe clusters

N-Doped Carbon Nanotube Shell Encapsulating the NiFe Metal Core for Enhanced Catalytic Stability in Methanol Oxidation Reaction by the Structural Cooperation Mechanism

Exploitation of high-efficiency catalysts toward methanol oxidation is a pivotal step to promote the commercialization of direct methanol fuel cells. Herein, a strategy is demonstrated to prepare nitrogen-doped carbon nanotubes with NiFe metal particles (NiFe@N-CNT) as the carrier material of Pt nanoparticles. Combining SEM and TEM, NiFe metal particles are fully encapsulated in N-CNTs, and they form the metal core and carbon nanotube shell structure based on the structural cooperation mechanism. Surprisingly, the as-prepared Pt/NiFe@N-CNT catalyst shows superior catalytic activity (1023 mA mg^-1_Pt) compared to commercial Pt/C (392 mA mg^-1_Pt), Pt/Ni@N-CNT (331 mA mg^-1_Pt), and Pt/Fe@N-CNT (592 mA mg^-1_Pt). After 1000 cycles, Pt/NiFe@N-CNT maintains the optimal catalytic activity (588 mA mg^-1_Pt), and its mass activity loss is 42.5%, which is better than those of commercial Pt/C (64.0%), Pt/Ni@N-CNT (67.7%), and Pt/Fe@N-CNT (59.6%) catalysts, indicating that the Pt/NiFe@N-CNT catalyst achieves excellent catalytic activity and stability, which stems chiefly from the homodispersed Pt nanoparticles and the generation of the metal core-carbon nanotube shell based on the structural cooperation mechanism. This study reports the facile construction of a metal core-carbon nanotube shell structure, which intrinsically ameliorates structural collapse of carrier material, thereby improving the catalytic stability of the Pt-based catalyst and broadening the view for design of other desire catalysts in methanol oxidation.

Optimization of Oxygen Evolution Reaction with Electroless Deposited Ni-P Catalytic Nanocoating

The low efficiency of water electrolysis mostly arises from the thermodynamic uphill oxygen evolution reaction. The efficiency can be greatly improved by rationally designing low-cost and efficient oxygen evolution anode materials. Herein, we report the synthesis of Ni-P alloys adopting a facile electroless plating method under mild conditions on nickel substrates. The relationship between the Ni-P properties and catalytic activity allowed us to define the best conditions for the electroless synthesis of highperformance Ni-P catalysts. Indeed, the electrochemical investigations indicated an increased catalytic response by reducing the thickness and Ni/P ratio in the alloy. Furthermore, the Ni-P catalysts with optimized size and composition deposited on Ni foam exposed more active sites for the oxygen evolution reaction, yielding a current density of 10 mA cm-2 at an overpotential as low as 335 mV, exhibiting charge transfer resistances of only a few ohms and a remarkable turnover frequency (TOF) value of 0.62 s-1 at 350 mV. The present study provides an advancement in the control of the electroless synthetic approach for the design and large-scale application of high-performance metal phosphide catalysts for electrochemical water splitting.

Catalytically active gold clusters with atomic precision for noninvasive early intervention of neurotrauma

Background

Neurotrauma is a worldwide public health problem which can be divided into primary and secondary damge. The primary damge is caused by external forces and triggers the overproduction of peroxides and superoxides, leading to long-lasting secondary damage including oxidative stress, wound infection and immunological reactions. The emerging catalysts have shown great potential in the treatment of brain injury and neurogenic inflammation, but are limited to biosafety issues and delivery efficiency.

Results

Herein, we proposed the noninvasive delivery route to brain trauma by employing highly active gold clusters with enzyme-like activity to achieve the early intervention. The decomposition rate to H₂O₂ of the ultrasmall gold clusters is 10 times that of glassy carbon (GC) electrodes, indicating excellent catalytic activity. The gold clusters can relieve the oxidative stress and decrease the excessive O₂^·− and H₂O₂ both in vitro and in vivo. Besides, gold clusters can accelerate the wound healing of brain trauma and alleviate inflammation via inhibiting the activation of astrocytes and microglia through noninvasive adminstration. decrease the peroxide and superoxide of brain tissue.

Conclusions

Present work shows noninvasive treatment is a promising route for early intervention of brain trauma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01071-4.

In Situ/Operando Electrocatalyst Characterization by X-ray Absorption Spectroscopy

During the last decades, X-ray absorption spectroscopy (XAS) has become an indispensable method for probing the structure and composition of heterogeneous catalysts, revealing the nature of the active sites and establishing links between structural motifs in a catalyst, local electronic structure, and catalytic properties. Here we discuss the fundamental principles of the XAS method and describe the progress in the instrumentation and data analysis approaches undertaken for deciphering X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. Recent usages of XAS in the field of heterogeneous catalysis, with emphasis on examples concerning electrocatalysis, will be presented. The latter is a rapidly developing field with immense industrial applications but also unique challenges in terms of the experimental characterization restrictions and advanced modeling approaches required. This review will highlight the new insight that can be gained with XAS on complex real-world electrocatalysts including their working mechanisms and the dynamic processes taking place in the course of a chemical reaction. More specifically, we will discuss applications of in situ and operando XAS to probe the catalyst's interactions with the environment (support, electrolyte, ligands, adsorbates, reaction products, and intermediates) and its structural, chemical, and electronic transformations as it adapts to the reaction conditions.

Room temperature single electron transistor based on a size-selected aluminium cluster

Single electron transistors (SETs) are powerful devices to study the properties of nanoscale objects. However, the capabilities of placing a nano-object between electrical contacts under pristine conditions are lacking. Here, we developed a versatile two point contacting approach that tackles this challenge, which is demonstrated by constructing in situ a prototypical SET device consisting of a single aluminium cluster of 66 ± 5 atoms, deposited directly in a gold nanogap using an innovative cluster beam deposition technique. The gate driven conductance measurements demonstrate Coulomb blockade oscillations at room temperature correlating with an extracted charging energy of 0.14 eV, which is five times larger than k_BT at 300 K. Our work provides a model SET device platform to probe the quantum features of nano-objects with high precision.