Au@Co2P core/shell nanoparticles as a nano-electrocatalyst for enhancing the oxygen evolution reaction

Enhanced Therapeutic Potential of Irreversible Electroporation under Combination with Gold-Doped Mesoporous Silica Nanoparticles against EMT-6 Breast Cancer Cells

Irreversible electroporation (IRE) is a non-thermal tumor ablation technique that delivers short pulses of strong electric fields to cancer tissues and induces cell death through the destruction of cell membranes. Here, we synthesized gold-doped mesoporous silica nanoparticles (Au-MSNs) via incipient wetness impregnation and evaluated the therapeutic potentials of combination therapy with IRE. The fabricated Au-MSNs had around 80-100 nm of particle size and were successfully end-doped with Au nanoparticles. Combination treatment of IRE (800 V/cm) and Au-MSNs (100 μg/mL) increased cell membrane permeability by 25-fold compared with single IRE treatment. Cellular reactive oxygen species (ROS) and lipid peroxidation of EMT-6 cells were significantly increased by 14- and 265-fold, respectively, under combination treatment of IRE (800 V/cm) and Au-MSNs (100 µg/mL). Cytotoxic cell death increased by 28% under a combination treatment of IRE (800 V/cm) and Au-MSNs (100 ug/mL) over single IRE. Our studies suggest that the combination treatment of IRE with Au-MSNs can enhance the therapeutic efficacy of IRE for breast cancer.

Nonmetallic Active Sites on Nickel Phosphide in Oxygen Evolution Reaction

Efficient and durable catalysts are crucial for the oxygen evolution reaction (OER). The discovery of the high OER catalytic activity in Ni12P5 has attracted a great deal of attention recently. Herein, the microscopic mechanism of OER on the surface of Ni12P5 is studied using density functional theory calculations (DFT) and ab initio molecular dynamics simulation (AIMD). Our results demonstrate that the H2O molecule is preferentially adsorbed on the P atom instead of on the Ni atom, indicating that the nonmetallic P atom is the active site of the OER reaction. AIMD simulations show that the dissociation of H from the H2O molecule takes place in steps; the hydrogen bond changes from Oa-H⋯Ob to Oa⋯H-Ob, then the hydrogen bond breaks and an H+ is dissociated. In the OER reaction on nickel phosphides, the rate-determining step is the formation of the OOH group and the overpotential of Ni12P5 is the lowest, thus showing enhanced catalytic activity over other nickel phosphides. Moreover, we found that the charge of Ni and P sites has a linear relationship with the adsorption energy of OH and O, which can be utilized to optimize the OER catalyst.

Coordination environment evolution of Co(ii) during dehydration and re-crystallization processes of KCoPO4·H2O towards enhanced electrocatalytic oxygen evolution reaction

Development of efficient and stable electrodes for electrocatalytic oxygen evolution reaction (OER) is essential for energy storage and conversion applications, such as hydrogen generation from water splitting, rechargeable metal–air batteries and renewable fuel cells. Alkali metal cobalt phosphates show great potential as OER electrocatalysts. Herein, an original electrode design strategy is reported to realize an efficient OER electrocatalyst through engineering the coordination geometry of Co(ii) in KCoPO₄·H₂O by a facile dehydration process. Experimental result indicated that the dehydration treatment is accompanied by a structural transformation from orthorhombic KCoPO₄·H₂O to hexagonal KCoPO₄, involving a concomitant coordination geometry evolution of Co(ii) from octahedral to tetrahedral configuration. More significantly, the local structural evolution leads to an advantageous electronic effect, i.e. increased Co–O covalency, resulting in an enhanced intrinsic OER activity. To be specific, the as-produced KCoPO₄ can deliver a current density of 10 mA cm⁻² at a low overpotential of 319 mV with a small Tafel slope of 61.8 mV dec⁻¹ in alkaline electrolyte. Thus, this present research provides a new way of developing alkali metal transition-metal phosphates for efficient and stable electrocatalytic oxygen evolution reaction.

Coordination environment evolution of potassium cobalt phosphate towards enhanced electrocatalytic oxygen evolution reaction.