Surface Equilibration Mechanism Controls the Stability of a Model Codeposited Glass Mixture of Organic Semiconductors.

While previous work has identified the conditions for preparing ultrastable single-component organic glasses by physical vapor deposition (PVD), little is known about the stability of codeposited mixtures. Here, we prepared binary PVD glasses of organic semiconductors, TPD (N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine) and m-MTDATA (4,4',4″-Tris[phenyl(m-tolyl)amino]triphenylamine), with a 50:50 mass concentration over a wide range of substrate temperatures (Tsub). The enthalpy and kinetic stability are evaluated with differential scanning calorimetry and spectroscopic ellipsometry. Binary organic semiconductor glasses with exceptional thermodynamic and kinetic stability comparable to the most stable single-component organic glasses are obtained when deposited at Tsub = 0.78-0.90Tg (where Tg is the conventional glass transition temperature). When deposited at 0.94Tg, the enthalpy of the m-MTDATA/TPD glass equals that expected for the equilibrium liquid at that temperature. Thus, the surface equilibration mechanism previously advanced for single-component PVD glasses is also applicable for these codeposited glasses. These results provide an avenue for designing high-performance organic electronic devices.

Correction: Single phase of spinel Co2RhO4 nanotubes with remarkably enhanced catalytic performance for the oxygen evolution reaction.

Correction for 'Single phase of spinel Co2RhO4 nanotubes with remarkably enhanced catalytic performance for the oxygen evolution reaction' by So Yeon Kim et al., Nanoscale, 2019, 11, 9287-9295.

Single phase of spinel Co2RhO4 nanotubes with remarkably enhanced catalytic performance for the oxygen evolution reaction.

We report the effective crystal growth for a unique single phase of spinel cobalt rhodium oxide (Co2RhO4) nanotubes via the electrospinning process combined with the thermal annealing process. In the spinel structure of the electrospun Co2RhO4 nanotubes, Co3+ cations and Rh3+ cations randomly occupy the octahedral sites, while the remaining half of the Co2+ cations occupy the centres of the tetrahedral sites as proved by microscopic and spectroscopic observations. Furthermore, electrospun spinel Co2RhO4 nanotubes exhibit excellent catalytic performances with the least positive onset potential, greatest current density, and low Tafel slope which are even better than those of the commercial Ir/C electrocatalyst for the oxygen evolution reaction (OER) in alkaline solution. Our demonstration of significantly enhanced OER activity with a single phase of electrospun spinel Co2RhO4 nanotubes thus opens up the broad applicability of our synthetic methodology for accessing new OER catalysis.