The electrocatalytic oxidation of urea on nickel-graphene and nickel-graphene oxide composite electrodes

Highly Efficient Urea Oxidation via Nesting Nano-Nickel Oxide in Eggshell Membrane-Derived Carbon

“…[1][2][3][4] Also, there is 2-2.5 wt.% urea from mammal urine, therefore, 0.5 million tons of additional fuels will be produced per year just from human urine (240 million tons each year). [5][6][7][8] Electrochemical oxidation has been recognized as an efficient strategy for urea conversion and wastewater remediation. [9][10][11] Thus, the chemical energy harvested from urea/urine can be converted to electricity via urea oxidation reaction (UOR).…”

“…In recent years, there has been a fast-growing trend in developing urea (CO­(NH 2 ) 2 ) as a substitute H 2 carrier in energy conversion due to its high energy density, nontoxicity, stability, and nonflammability . Urea, a byproduct in the metabolism of proteins and a frequent contaminant in wastewater, is an abundant compound that has demonstrated favorable characteristics as a hydrogen-rich fuel source with 6.7 wt % gravimetric hydrogen content. − Also, there is 2–2.5 wt % urea from mammal urine; therefore, 0.5 million ton of additional fuels will be produced per year just from human urine (240 million ton each year). − Electrochemical oxidation has been recognized as an efficient strategy for urea conversion and wastewater remediation. − Thus, the chemical energy harvested from urea/urine can be converted to electricity via urea oxidation reaction (UOR). − Moreover, the removal of urea from water is a priority for improving drinking water quality and presents an opportunity for UOR . However, the transition of UOR from theory and laboratory experiments to real-world applications is largely limited by the conversion efficiency, catalyst cost, and feasibility of wide-spread usage …”

In Situ Growth of Porous Ultrathin Ni(OH)2 Nanostructures on Nickel Foam: An Efficient and Durable Catalysts for Urea Electrolysis

“…Finally, NF was dried in the laboratory air at room temperature for 1 day. To determine the effect of the activation time on the catalytic performance, the Ni(OH) 2 @NF electrodes with different activation times (15,30,90, and 120 min) were prepared using a similar procedure; the optimum time was determined to be 60 min (Figure S1).…”

“…To address the above issue, considerable attempts have been made for the design and fabrication of freestanding and nanostructured nickel-based catalysts and their derivatives, which are essentially composites comprising various highly conductive substrates such as a carbon-based substrate, ,− metal titanium substrate, − Cu foam, and NF substrate. − Among these highly conductive substrates, NF is not only commonly used as a substrate for constructing 3D electrocatalysts but also acts as a reactant substrate for the in situ preparation of Ni-based electrocatalysts; this is due to its interconnected 3D porous structure, excellent electrical conductivity, high intrinsic strength, and good corrosion resistance. − Yu et al ., for instance, developed a 3D NF/NiMoO nanorod nanocomposite for the UOR, which was prepared via an Ar-protected annealing process that used presynthesized NiMoO 4 · x H 2 O nanorods as parent materials. This catalyst required a small voltage requirement (1.37 V vs reversible hydrogen electrode) to attain a current density of 10 mA cm –2 and could sustain a current density of ∼80 mA cm –2 across a 25 h operation period .…”

An Overview of the Recent Developments in Metal Matrix Nanocomposites Reinforced by Graphene

“…Composite materials contain two or more distinct constituents which are engineered or naturally occurring, with remarkably various properties (chemical, physical and mechanical) [1,2,3,4,5]. In general, typical metal matrix composites (MMCs) reinforced by ceramic particles or fibers show superior features with respect to the unreinforced alloys [6,7,8,9,10].…”