Construction of nickel-doped cobalt hydroxides hexagonal nanoplates for advanced oxygen evolution electrocatalysis.

Oxygen vacancy of the catalyst is one of the most significant factors affecting the oxygen evolution reaction (OER) electrocatalysis, a key process for overall water splitting. Here, we report the oxygen vacancy engineering of Co(OH)2 hexagonal nanoplates by doping Ni element, which can efficiently lower the average Co oxidation state and thus optimize the Gibbs free energy of the intermediates, giving rise to the largely promoted OER performances. Impressively, the as-obtained oxygen-vacancy-rich Ni-doped Co(OH)2 hexagonal nanoplates manifest OER overpotential as low as 238 mV at 10 mA cm-2 in 1 M KOH solution, being superior to most of binary CoNi hydroxides. In accordance with the high OER activity, it also displays excellent durability in strong alkaline media over 40 h, presenting an advanced electrocatalyst for OER.

Fabrication of In Situ Nanofiber-Reinforced Molecular Composites by Nonequilibrium Self-Assembly.

Although the concept of molecular composites (MCs) is very promising, there are major obstacles arising from the immiscibility of the rigid-rod with the random-coil polymers. Here, we developed a novel method for fabricating an in situ reinforced MC system with nonequilibrium self-assembled nanofibrous structures based on bisphenol A epoxy resin, 4,4'-diaminodiphenylsulfone, bismaleimide, and a polyphenylene ether (PPO) oligomer. A variety of spectroscopic and morphological techniques were used to probe the structural evolution from the emergence of nanofibrils, to growth and aggregation of nanofibers, and then to the formation of in situ reinforced MC with strong interfacial interactions. The in situ nanofibers within the polymer matrix could be formed by the polymerization force extruding the PPO phase through the interspaces within the simultaneous interpenetrating network polymers during the cure process of the thermosetting resin system. Compared to the control sample, the in situ nanofiber-reinforced MC exhibited better thermal properties and flame retardancy. In particular, the obtained MC showed a significant improvement in glass transition temperature and mechanical properties, which were mainly attributed to the restriction of high thermal stability of PPO on the segmental motion of polymer chains, the toughening and reinforcement behaviors of PPO nanofibers on the matrix, and the chemical interaction at the PPO/matrix interface.

Multifunctional cyclotriphosphazene/hexagonal boron nitride hybrids and their flame retarding bismaleimide resins with high thermal conductivity and thermal stability.

A novel hybridized multifunctional filler (CPBN), cyclotriphosphazene/hexagonal boron nitride (hBN) hybrid, was synthesized by chemically coating hBN with hexachlorocyclotriphosphazene and p-phenylenediamine, its structure was systemically characterized. Besides, CPBN was used to develop new flame retarding bismaleimide/o,o'-diallylbisphenol A (BD) resins with simultaneously high thermal conductivity and thermal stability. The nature of CPBN has a strong influence on the flame behavior of the composites. With the addition of only 5 wt % CPBN to BD resin, the thermal conductivity increases 2 times; meanwhile the flame retardancy of BD resin is remarkably increased, reflected by the increased limited oxygen index, much longer time to ignition, significantly reduced heat release rate. The thermogravimetric kinetics, structures of chars and pyrolysis gases, and cone calorimeter tests were investigated to reveal the unique flame retarding mechanism of CPBN/BD composites. CPBN provides multieffects on improving the flame retardancy, especially in forming a protective char layer, which means a more thermally stable and condensed barrier for heat and mass transfer, and thus protecting the resin from further combustion.