Zein, a major protein of corn, is rich in α-helical structure. It has an amphiphilic character and is capable of self-assembly. Zein can self-assemble into various mesostructures that may find applications in food, agricultural, and biomedical engineering. Understanding the mechanism of zein self-assembly at the nanoscale is important for further development of zein structures. In this work, high-resolution transmission electron microscopy (TEM) images revealed nanosize zein stripes, rings, and discs containing a 0.35 nm periodicity, which is characteristic of β-sheet. TEM images were interpreted in terms of the transformation of original α-helices into β-sheet conformation after evaporation-induced self-assembly (EISA). The presence of β-sheet was also detected by circular dichroism (CD) spectroscopy. Zein β-sheets self-assembled into stripes, which curled into rings. Rings formed discs and eventually spheres. The formation of zein nanostructures was believed to be the result of β-sheet orientation, alignment, and packing.

The growth of mesoporous quasi‐single‐crystalline Co3O4 nanobelts by topotactic chemical transformation from α‐Co(OH)2 nanobelts is realized. During the topotactic transformation process, the primary α‐Co(OH)2 nanobelt frameworks can be preserved. The phases, crystal structures, morphologies, and growth behavior of both the precursory and resultant products are characterized by powder X‐ray diffraction (XRD), electron microscopy—scanning electron (SEM) and transmission electron (TEM) microscopy, and selected area electron diffraction (SAED). Detailed investigation of the formation mechanism of the porous Co3O4 nanobelts indicates topotactic nucleation and oriented growth of textured spinel Co3O4 nanowalls (nanoparticles) inside the nanobelts. Co3O4 nanocrystals prefer [0001] epitaxial growth direction of hexagonal α‐Co(OH)2 nanobelts due to the structural matching of [0001] α‐Co(OH)2//[111] Co3O4. The surface‐areas and pore sizes of the spinel Co3O4 products can be tuned through heat treatment of α‐Co(OH)2 precursors at different temperatures. The galvanostatic cycling measurement of the Co3O4 products indicates that their charge–discharge performance can be optimized. In the voltage range of 0.0–3.0 V versus Li+/Li at 40 mA g−1, reversible capacities of a sample consisting of mesoporous quasi‐single‐crystalline Co3O4 nanobelts can reach up to 1400 mA h g−1, much larger than the theoretical capacity of bulk Co3O4 (892 mA h g−1).

Rational design of the microstructure and intrinsic active sites of nitrogen-doped carbon (NC) materials to achieve highly efficient oxygen reduction reaction (ORR) electrocatalysts is extremely important for many renewable energy devices. Herein, we develop a metal–organic framework (MOF) derived metal-free NC material via a simple and low-cost NH3 activation strategy. With NH3 activation, the ORR catalytic performance of the MOF-derived material shows a great promotion. The material outperforms commercial Pt/C catalyst toward ORR catalysis in alkaline media with ∼28 mV higher half-wave potential. This amazing ORR performance might be attributed to its large specific surface area, hierarchical porosity, and full exposure of valid N species (mainly graphitic-N) to the ORR, which result from the facile NH3 activation.

Zein, a major protein of corn, is soluble in binary mixtures of ethanol and water. It has an amphiphilic character and is capable of self-assembly into nano- and microsized rods, spheres, and films upon solvent evaporation. The formation of microspheres is of particular interest for the development of delivery systems. Control over structure formation requires a better understanding of zein behavior in solution. The objective of this work was to investigate the effect of zein concentration and the effect of ethanol-water ratio on the microphase behavior of zein solutions, believed to govern the morphology of microstructures after solvent evaporation. The Flory-Huggins solution theory was applied to model boundary lines between microphases in solution. The study generated information on the zein concentration-ethanol/water ratio conditions where microspheres are formed and provided insight into the microphase behavior of zein ethanolic solutions.

No abstract