A series of thin Pt films were deposited by dc magnetron sputtering with different power directly on a commercial hydrophobic carbon paper substrate at room temperature. Their electrochemical properties toward the oxygen reduction reaction were investigated in 0.5 M H₂SO₄ solution by means of cyclic voltametry (CV) and linear sweep voltametry (LSV) on rotating disc electrode (RDE). It was found that the increase of power leads to rise in the electrochemical active surface area (EASA) slightly up to 25 W, but further increase in power decreases surface area significantly. Electrochemical surface area is reaching a maximum of 29.68 m² g_Pt⁻¹ for 25 W. Rotating disk electrode experiments, also, show that increase of power yield more active catalyst toward to oxygen reduction reaction. As a result, 25 W coating power is the optimum for the preparation of the smallest and the most active Pt particle in catalytic film.

View full abstract

We present an isothermal, one-dimensional, steady-state model for an alkaline anion exchange membrane fuel cell (AAEMFC), in which the conducting ions (OH⁻) move from the cathode to the anode. While water is produced at the anode, it is consumed at the cathode along with oxygen. The water transport in the membrane comprises water flux by the electro-osmotic drag and the diffusive water flux because of the gradient of water concentration across the membrane. The present model is validated with the experimental data in the literature and the water transport in AAEMFC is discussed. By performing numerical simulations of four cases of humidity conditions (dry or fully humidified conditions for each anode and cathode), it is reconfirmed theoretically that anode humidification is more essential to secure good AAEMFC performance. In addition, water transport through the gas diffusion layers of anode and cathode as well as the membrane is examined to provide fundamental information about water management in the AAEMFC operations.

View full abstract

Single-walled carbon nanotubes and graphene (SWNTs/G) composite aerogel have been prepared by a hydrothermal method with aid of sodium alginate (SA) decoration and used for modification of glassy carbon electrode. The modified electrode was employed for the sensitive determination of metal ions using differential pulse anodic stripping voltammetry method. The results showed that the introduction of SA not only improved the uniformity of SWNTs/G composite, but also exhibited synergistic effect for detection of several kinds of heavy metal ion. The SA decorated SWNTs were inserted into graphene interlayers, resulting in more active sites and reactive surface area. As a result, the modified electrode exhibited attractive inter-electrode reproducibility and high sensitivity for detection of Pb²⁺, Cd²⁺ and Cu²⁺ ions.

View full abstract

A sodium secondary battery has been constructed by using a nonvolatile and nonflammable Na[FSA]-[C₃C₁pyrr][FSA] (FSA = bis(fluorosulfonyl)amide, C₃C₁pyrr = N-methyl-N-propylpyrrolidinium) ionic liquid, a NaCrO₂ positive electrode and a Na metal negative electrode. The charge-discharge performance is evaluated over a wide temperature range of −20–90°C. It has been demonstrated that the sodium secondary battery has long cycle lives both at a high temperature of 90°C and at a low temperature of 0°C. Thus, the ionic liquid-based sodium secondary battery is expected to be a viable alternative to lithium ion battery for many applications.

View full abstract