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The composite electrode of NiCo oxide supported by porous carbon was synthesized for nitrite oxidation and nitrate electro-sorption. The crystal structure and chemical state of the Co and Ni oxyhydroxides which were precipitated on loofah-derived activated carbon (AC) using hypochlorite were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and BET surface area. The voltammetry showed that the redox couple of Co(II)/Co(III) and Ni(II)/Ni(III) as the mediator catalytically transferred the electrons of NO

Effects of Pd nanoclusters in PdxSn100-x/Ni electrodes with preferred diffraction planes of Sn(101) and Sn(200) plated on a nickel foam were studied on electrochemical reduction reaction of nitrate (NO3-). NO3- converted to NO2-, N2 and NH4+ by surface Hads was assessed at different Pd to Sn ratio through the electroanalysis and batch electrolysis at constant current mode. Pd loading obviously enhanced the current density of proton diffusion-controlled Sn0/Sn(II) transition. NO3- reduction was much more efficient on PdSn(200) than on PdSn(101); 53% of N2 yield on Sn(200)/Ni could increase up to 79% on Pd5Sn(200)95/Ni, while further increasing Pd loading would gradually increase NH4+ yield. The steady-state kinetics proposed a scheme of adsorption and deoxygenation of NO3- on Sn(200) and hydrogenation of NO2- to N2 on Pd NPs beside the Sn crystals.

The crystal habit of metallic tin (Sn) on a nickel foam electrode (Sn/Ni) was manipulated by cationic surfactants in order to assess the selective conversion of NO3−. The Sn electroplating additive included benzethonium chloride (BZT), cetylpyridinium chloride (CPC), cetyltrimethylammonium chloride (CTAC), and hexyltrimethylammonium bromide (C6TAB). Characterization showed that FSn(200) (= Sn(200)/[Sn(200) + Sn(101)]), which indicated that the preference of the Sn(200) facet was modified by the surfactants. FSn(200) was in the following order: BZT > CPC > CTAC > C6TAB-Sn/Ni. As FSn(200) increased, a positive correlation between selectivity of N2 (SN2) and FSn(200) existed. The highest amount of SN2 (as high as 65 %) was obtained at FSn(200) = 0.95. The consecutive kinetics was derived to define the formation rate of the nitrogen compound in the constant current mode. NO3- and NO2- adsorption determined the effectiveness of nitrate reduction on the Sn(200) surface, which efficiently mediated H species formation.

Surfactants, namely, cetyltrimethylammonium chloride, polydiallyldimethylammonium chloride, and benzethonium chloride were used to control the crystal growth of metallic Cu nanoparticles supported on stainless steel mesh electrodes as to improve the selective electrochemical conversion of NO3− to non-toxic N2. Results showed that the Cu(200)/Cu(111) ratio controlled the selectivity of N2, NO2−, and NH4+. The Kd value increased from 10% to 30% when the Cu(200)/Cu(111) intensity ratio was decreased 60% to 30%, meaning increase Cu(111) increased N2 production. Furthermore, the presence of a second metal, namely, Pd increased the N2 selectivity. The best N2 yield (XN2 = 22%), occurring on monometallic Cu, synthesized with BZT at 1-time CMC was further increased to XN2 = 65% over bimetallic Pd0.27Cu0.73/SS. The selectivity of nitrite (SNO2-) and ammonium (SNH4+) on Cu/SS were 33.1 and 43.5%, respectively, which were decreased to 0.30 and 34.0%, respectively, on bimetallic Pd0.27Cu0.73/SS.