Y.Y. Tong

Three-dimensional astrocyte-network Ni–P–O compound with superior electrocatalytic activity and stability for methanol oxidation in alkaline environments

Three Ni–P–O compound catalysts with tunable architectures and compositions have been fabricated using a facile one-pot solvothermal method, which are named astrocyte-network Ni–P (Ni–Pan), silkworm cocoon-like Ni–P (Ni–Psc), and microsphere Ni–P (Ni–Pm), respectively. The final architecture of the Ni–P–O catalysts is strongly dependent on the Ni2+/H2PO2− molar ratio in the reaction system, which leads to a delicate balance between kinetic and thermodynamic growth regimes. Three-dimensional ensemble of Ni–Pan with a higher P content is composed of many amorphous Ni–P nanowires with a diameter of about 4 nm, which delivers a significantly larger BET surface area of 500.5 m2 g−1. Moreover, nickel phosphides and nickel phosphates are formed in the three Ni–P–O samples. Ni–Pan exhibits a higher peak current density of ∼1490 A g−1, better electrode accessibility, faster charge-transfer process, and long-term chronoamperometry stability (≥20 000 s) toward methanol oxidation in alkaline solution, which are superior to most state-of-art Ni–P catalysts and the Ni–Psc and Ni–Pm in this case. The superior catalytic performance of the Ni–Pan catalyst is attributed to its unique microstructure and compositions. According to X-ray photoelectron spectroscopy, a strong electronic interaction between nickel phosphides and nickel phosphates might also contribute to the improved catalytic activity of the Ni–Pan catalyst.

Synthesis and electrochemical performance of xLiV3O8·yLi3V2(PO4)3/rGO composite cathode materials for lithium ion batteries

A series of xLiV3O8·yLi3V2(PO4)3/rGO (x : y = 2 : 1, 3 : 1, 1 : 1, 1 : 2, and 1 : 3) composites are synthesized by simple mechanical mixing of LiV3O8 and Li3V2(PO4)/rGO, which are prepared by the hydrothermal method and the sol–gel route, respectively. From scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs, the composites are found to be a mixture of rod-like LiV3O8 particles and flower-shaped Li3V2(PO4)/rGO. Among these composites, the 2LiV3O8·Li3V2(PO4)/rGO electrode delivers an initial discharge capacity of 197 mA h g−1 at a current density of 100 mA g−1 between 2.0 V and 4.3 V, and shows the best comprehensive electrochemical property. The diffusion coefficients of Li ions in the 2LiV3O8·Li3V2(PO4)/rGO electrode are in the range of 10−11.5 to 10−9.5 cm2 s−1 obtained using the galvanostatic intermittent titration technique (GITT).

Microstructure and corrosion behavior of Cr and Cr–P alloy coatings electrodeposited from a Cr( iii ) deep eutectic solvent

Cr and Cr–P coatings were electrodeposited on Fe substrates from non-aqueous deep eutectic solvent-based electrolytes containing Cr(III). The optimized deposition parameters for the coating process were explored. A two-step process of Cr(III) reduction occurred, i.e. Cr(III) → Cr(II) → Cr(0), and the controlling step was promoted by adding NH4H2PO2. It was found that an electro-brush plated Ni underlayer was essential to obtain a smooth and compact Cr or Cr–P coating on the Fe substrate. The structure and composition of the as-deposited coatings were thoroughly analyzed. The corrosion behavior of the Cr and Cr–P coatings is quite different in 3.5 wt% NaCl and 0.1 M H2SO4 solutions. The diplex effects of the layered structures and ion-selective components in the as-prepared Cr-based coatings are suggested to be responsible for the different corrosion mechanism in different corrosion media.