Electrochemical surface nitriding of titanium in molten salt system

Electrochemical synthesis of transition metal oxide nitrides with ε-TaN, δ-NbN and γ′-Mo2N structure type in a molten salt system

The three nitrides ε-TaN, δ-NbN and γ′-Mo2N have been synthesized electrochemically from the elements at 450°C in a molten salt mixture LiCl/KCl:Li3N. For all compounds the working electrode consisting of a tantalum, niobium or molybdenum foil was anodically polarized and the system was fed with dry nitrogen. The applied constant voltage was 2.5 V (for ε-TaN), 2.2 V (for δ-NbN), and 2.8 V (for γ′-Mo2N). Chemical analysis on N and O resulted in compositions of TaN0.81(1)O0.13(2), NbN1.17(2)O0.28(1) and MoN0.88(1)O0.11(1), respectively. Lattice parameters of ε-TaN refined by the Rietveld method are a =  519.537(4) and c = 291.021(3) pm. The other two nitrides crystallize in the cubic system (rocksalt type) with a = 436.98(2) pm for δ-NbN and with a = 417.25(2) pm for γ′-Mo2N.

Controlled electrochemical doping of graphene-based 3D nanoarchitecture electrodes for supercapacitors and capacitive deionisation

Chemically-doped graphenes are promising electrode materials for energy storage and electrosorption applications. Here, an affordable electrochemical green process is introduced to dope graphene with nitrogen. The process is based on reversing the polarity of two identical graphene oxide (GO) electrodes in molten KCl-LiCl-Li₃N. During the cathodic step, the oxygen functional groups on the GO surface are removed through direct electro-deoxidation reactions or a reaction with the deposited lithium. In the anodic step, nitrogen is adsorbed onto the surface of graphene and subsequently reacts to form nitrogen-doped graphene. The doping process is controllable, and graphene with up to 7.4 at% nitrogen can be produced. The electrochemically treated electrodes show a specific capacitance of 320 F g^-1 in an aqueous KOH electrolyte and maintain 96% of this value after 10 000 cycles. The electrodes also display excellent electrosorption performance in capacitive deionisation devices with the salt removal efficiency reaching up to 18.6 mg g^-1.

Ambient temperature deposition of gallium nitride/gallium oxynitride from a deep eutectic electrolyte, under potential control

A ternary, ionically conducting, deep eutectic solvent based on acetamide, urea and gallium nitrate is reported for the electrodeposition of gallium nitride/gallium indium nitride under ambient conditions; blue and white light emitting photoluminescent deposits are obtained under potential control.

Thermodynamics of the N2/N3- Redox Couple in a LiBr−KBr−CsBr Melt

Nitrogen electrode reaction has been investigated in a LiBr-KBr-CsBr melt containing Li3N. The reaction N3- --> 1/2N2 + 3e- is confirmed by quantitative analysis of anodically evolved gas. The Nernst relation holds for the rest potential of Ni electrodes at a nitrogen gas pressure, pN2, of 0.05-1.0 atm and an anion fraction of the N3- ions, xN3-, of 0.003-0.010 (anion fraction). Then, the standard formal potential of the N2/N3- couple, , is evaluated to be 0.251 +/- 0.009 V versus Li+/Li (pN2 = 1 atm, xN3- = 1) at 673 K. The dependence of on the temperature (570-730 K) gives a linear relation, whose slope is (-0.930 +/- 0.117) x 10(-3) V K(-1). Thermodynamic quantities for the formation of Li3N in the melt are also estimated.