The rising H economy urgently demands active, durable and cost-effective catalysts for the electrochemical hydrogen evolution reaction (HER). However, improving the HER performance of electrocatalysts in alkaline media is still challenging. Herein, we report the development of a nickel hydroxide-cobalt disulfide nanowire array on a carbon cloth (Ni(OH)-CoS/CC) as a hybrid catalyst to significantly enhance the HER activity in alkaline solutions. Benefitting from heterogeneous interfaces in this 3D hybrid electrocatalyst, Ni(OH)-CoS/CC shows superior HER activity with only 99 mV overpotential to drive a current density of 20 mA cm in 1.0 M KOH, which is 100 mV less than that of CoS/CC. Moreover, Ni(OH)-CoS/CC exhibits long-term electrochemical durability with the maintenance of its catalytic activity for 30 h. Density functional theory calculations are performed to gain further insight into the effect of Ni(OH)-CoS interfaces, revealing that Ni(OH) plays a key role in water dissociation to hydrogen intermediates and CoS facilitates the adsorption of hydrogen intermediates and H generation. This work not only develops a promising electrocatalyst for the alkaline HER, but also paves a way to enhance the alkaline HER activity of CoSvia the interface engineering strategy.

Electrolytic hydrogen generation needs earth-abundant oxygen evolution reaction electrocatalysts that perform efficiently at mild pH. Here, the development of amorphous nickel-cobalt-borate nanosheet arrays on macroporous nickel foam (NiCo-Bi/NF) as a 3D catalyst electrode for high-performance water oxidation in near-neutral media is reported. To drive a current density of 10 mA cm , the resulting NiCo-Bi/NF demands an overpotential of only 430 mV in 0.1 m potassium borate (K-Bi, pH 9.2). Moreover, it also shows long-term electrochemical durability with maintenance of catalytic activity for 20 h, achieving a high turnover frequency of 0.21 s at an overpotential of 550 mV.

The nucleation and crystallization kinetics of lamellar crystalline−amorphous diblock copolymer poly(ε-caprolactone)-b-poly(4-vinylpyridine) (PCL−P4VP) was investigated by ultrafast differential scanning calorimetry (UFDSC) with temperature scanning rates up to 10 000 K/s and compared with that of poly(ε-caprolactone) (PCL) homopolymer. We found that the critical cooling rate (ccr) to get the fully amorphous PCL is 1 order of magnitude slower than that for PCL homopolymer with the similar molecular weight. Isothermal nucleation and crystallization of PCL block in the PCL−P4VP copolymer and PCL homopolymer were studied covering times from 10 −2 to 10 3 s and temperatures from 200 K (10 K below the glass transition temperature of PCL) to 300 K (about 40 K below the equilibrium melt temperature of PCL). It was found that the PCL block in PCL−P4VP copolymer experienced a slower homogeneous nucleation rate as well as crystallization rate than PCL homopolymer, indicating that even the local nucleation events of PCL chains is affected by the long-range glassy P4VP in copolymer. The confinement also hinders the long-range diffusion of PCL chains and becomes more effective once the chains get the mobility from the glassy state at crystallization temperatures above the T g . Another effect of the confinement is the lower Avrami index in copolymer than that in homopolymer attributed to the restricted growth dimension under confinement. The results reported here might enhance the understanding of confinement effect on crystallization and give new details on the nucleation kinetics under nanoscale confinement.

A smart, two-photon fluorescent GC–NABP nanoprobe with pH-dependent surface charge conversion was developed for tumor-targeted visualization of H2O2.