Electroplating of surfactant-modified tin catalyst over a nickel foam electrode (Sn/Ni) for selective N2 yield from nitrate reduction as affected by Sn(200) and Sn(101) crystal facets

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 (C(6)TAB). Characterization showed that F-Sn(200) (= Sn(200)/[Sn(200) + Sn(101)]), which indicated that the preference of the Sn(200) facet was modified by the surfactants. F-Sn(200) was in the following order: BZT > CPC > CTAC > C(6)TAB-Sn/Ni. As F-Sn(200) increased, a positive correlation between selectivity of N-2 (S-N2) and F-Sn(200) existed.The highest amount of S-N2 (as high as 65 %) was obtained at F-Sn(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.

Automated summary

The crystal habit of metallic tin on a nickel foam electrode was manipulated using cationic surfactants to assess the selective conversion of NO3-. Different surfactants were found to modify the preference of tin crystal facets, affecting the selectivity towards N-2 and ultimately the efficiency of nitrate reduction.