Mohamed F. Aly Aboud

Room-temperature synthesis of zinc oxide nanoparticles in different media and their application in cyanide photodegradation

Cyanide is an extreme hazard and extensively found in the wastes of refinery, coke plant, and metal plating industries. A simple, fast, cost-effective, room-temperature wet chemical route, based on cyclohexylamine, for synthesizing zinc oxide nanoparticles in aqueous and enthanolic media was established and tested for the photodegradation of cyanide ions. Particles of polyhedra morphology were obtained for zinc oxide, prepared in ethanol (ZnOE), while spherical and some chunky particles were observed for zinc oxide, prepared in water (ZnOW). The morphology was crucial in enhancing the cyanide ion photocatalytic degradation efficiency of ZnOE by a factor of 1.5 in comparison to the efficiency of ZnOW at an equivalent concentration of 0.02 wt.% ZnO. Increasing the concentration wt.% of ZnOE from 0.01 to 0.09 led to an increase in the photocatalytic degradation efficiency from 85% to almost 100% after 180 min and a doubling of the first-order rate constant (k).

Rational design of three-dimensional graphene encapsulated core–shell FeS@carbon nanocomposite as a flexible high-performance anode for sodium-ion batteries

The development of high-performance electrochemical energy storage systems is highly dependent on the synergistical structural design of electrode materials and whole electrodes with appropriate compositions. Here we create a novel flexible three-dimensional graphene (3DG) hybrid electrode with a core–shell FeS@carbon (FeS@C) nanocomposite encapsulated within 3DG by one-step thermal transformation of the deliberately designed 3DG wrapped metal–organic framework (3DG/MOF) composite based on the newly disclosed spatially confined phase separation of the metal and organic moieties of MOFs and the following in situ composition transformation mechanism. Benefitting from effective ion/charge transport in the whole electrode and the robust structural stability of FeS during electrochemical processes guaranteed by the highly interpenetrated porous conductive network of 3DG and the carbon protective layer with N- and S-codoping, the free-standing 3DG/FeS@C electrode delivers an ultrahigh specific capacity of 632 mA h g−1 after 80 cycles at 100 mA g−1, and excellent rate capacities of 363.3 and 152.5 mA h g−1 at 1 and 6 A g−1 with unprecedented cycling stability with a capacity retention of 97.9% after 300 cycles at 1 A g−1, which is the best ever reported result for FeS-based anode materials for sodium ion batteries. This study opens up a new MOF-based phase separation avenue to construct sophisticated 3DG wrapped core@shell nanocomposites and represents an important step to the structural design of high-performance electrodes for electrochemical energy storage.

Ultrathin Nitrogen‐Doped Carbon Layer Uniformly Supported on Graphene Frameworks as Ultrahigh‐Capacity Anode for Lithium‐Ion Full Battery

The designable structure with 3D structure, ultrathin 2D nanosheets, and heteroatom doping are considered as highly promising routes to improve the electrochemical performance of carbon materials as anodes for lithium-ion batteries. However, it remains a significant challenge to efficiently integrate 3D interconnected porous frameworks with 2D tunable heteroatom-doped ultrathin carbon layers to further boost the performance. Herein, a novel nanostructure consisting of a uniform ultrathin N-doped carbon layer in situ coated on a 3D graphene framework (NC@GF) through solvothermal self-assembly/polymerization and pyrolysis is reported. The NC@GF with the nanosheets thickness of 4.0 nm and N content of 4.13 at% exhibits an ultrahigh reversible capacity of 2018 mA h g-1 at 0.5 A g-1 and an ultrafast charge-discharge feature with a remarkable capacity of 340 mA h g-1 at an ultrahigh current density of 40 A g-1 and a superlong cycle life with a capacity retention of 93% after 10 000 cycles at 40 A g-1 . More importantly, when coupled with LiFePO4 cathode, the fabricated lithium-ion full cells also exhibit high capacity and excellent rate and cycling performances, highlighting the practicability of this NC@GF.

Sub-5 nm Ultrasmall Metal–Organic Framework Nanocrystals for Highly Efficient Electrochemical Energy Storage

Synthesis of ultrasmall metal-organic framework (MOF) nanoparticles has been widely recognized as a promising route to greatly enhance their properties but remains a considerable challenge. Herein, we report one facile and effective spatially confined thermal pulverization strategy to successfully transform bulk Co-MOF particles into sub-5 nm nanocrystals encapsulated within N-doped carbon/graphene (NC/G) by using conducting polymer coated Co-MOFs/graphene oxide as precursors. This strategy involves a feasible mechanism: calcination of Co-MOFs at proper temperature in air induces the partial thermal collapse/distortion of the framework, while the uniform coating of a conducting polymer can significantly improve the decomposition temperature and maintain the component stability of Co-MOFs, thus leading to the pulverization of bulk Co-MOF particles into ultrasmall nanocrystals without oxidation. The pulverization of Co-MOFs significantly increases the contact area between Co-MOFs with electrolyte and shortens the electron and ion transport pathway. Therefore, the sub-5 nm ultrasmall MOF nanocrystals-based composites deliver an ultrahigh reversible capacity (1301 mAh g-1 at 0.1 A g-1), extraordinary rate performance (494 mAh g-1 at 40 A g-1), and outstanding cycling stability (98.6% capacity retention at 10 A g-1 after 2000 cycles), which is the best performance achieved in all reported MOF-based anodes for lithium-ion batteries.

Cyclo­hexyl­ammonium nitrate

In the title salt, C6H14N+·NO3 −, the cyclohexyl ring adopts a chair conformation. The ammonium group occupies an equatorial position and the crystal struture is stabilized by intermolecular N—H⋯O hydrogen-bonding interactions, resulting in a three-dimensional network.

Experimental implementation of MPPT for PV systems

Solar panel efficiency is an essential parameter in determining the cost of converting solar energy into electrical energy. This paper addresses a technique for maximizing energy extraction from photovoltaic (PV) solar systems using power electronic circuits to achieve maximum power point tracking. Design and implementation details are presented, illustrating the perturbation and observation algorithm based on DC-DC power converter. Simulations are done in Matlab/Simulink environments, and experimental implementation is conducted in a developed PV testbed. Analysis of the recorded results reveals the potential of the presented techniques in enhancing the efficiency of energy extraction from PV systems.