Jinbiao Wang

A route to reducing the wear of the metal counterpart in the friction of meatal against diamond-like carbon (DLC) is to form a lubricating tribofilm on the metal counterface. However, in liquid lubricating conditions, the formation of tribofilm can be influenced by both the lubricating medium and the counterpart material. Here we report the effect of lubricating biomolecule and doping fluorine element on the formation of tribofilm in fluorinated DLC (FDLC)-Ti6Al4V friction system. A group of ball-on-disc frictional experiments with different sliding speeds and normal loads were performed in phosphate buffer solution (PBS) and bovine serum albumin (BSA) solution. The results showed the formation of tribofilm was inhibited by the absorption of biomolecules on the frictional surface, thus improving the friction coefficient and wear of Ti6Al4V counterpart. Doping fluorine into DLC film also can restrain the formation of tribofilm on Ti6Al4V counterface. As a result, tribofilm is difficult to form when Ti6Al4V counterface slides against FDLC in BSA solution. Fluorinated DLC film should be considered carefully for the anti-wear use in body fluid containing biomolecules because it might cause severe wear of the counterpart material.

Ni(OH)2 electrocatalysts have acquired lots of research attentions as ideal substitutes for noble metals. However, their electrocatalytic performance still cannot meet the demands for applications due to the difficulties in electron transfer and mass transport. According to kinetics principle, the construction of hollow structure is regarded as an effective method to achieve outstanding electrocatalytic performance. In this work, Ni(OH)2 hollow porous architecture (Ni(OH)2 HPA) was simply synthesized through a coordinating etching and precipitating (CEP) method for the building of enzymatic-free glucose sensors. Ni(OH)2 HPA presents large specific surface area (SSA), ordered diffusion channels, and structure stability. As a detection electrode for glucose, Ni(OH)2 HPA exhibits eminent electroactivity in terms of high sensitivity (1843 μA mM−1 cm−2), lower detection limit (0.23 μM), and short response time (1.4 s). The results demonstrate that Ni(OH)2 HPA has practical applications for construction of enzymatic-free electrochemical sensors. The design of hollow structure also provides an effective engineering method for high-performance sensors.