Photoassisted and electrochemical reduction of nitric acid to hydroxylamine and ammonia

Microwave synthesised Pd–TiO2 for photocatalytic ammonia production

“…A number of photocatalytic materials both doped and undoped; such as TiO 2 , 2,12-17 ZnO, [18][19][20] SrTiO 3 , 21 CdS, [22][23][24] ZnS, 25,26 Fe 2 O 3 , 19,27 and ZrO 2 (ref. 19) have been studied for photocatalytic nitrate reduction to date.…”

Photoinduced Electrochemical Reduction of Nitrite at an Electrochemically Roughened Silver Surface

“…Various approaches that have yielded some measure of success in lowering the high overpotential include the use of catalytic electrode materials, such as Ni, Zn, Cd, and Cu, the addition of catalysts such as metal cyclams to the electrolytic solution, and the adsorption of the catalyst on the electrode, as in the case of copper−phenanthroline complexes on graphite . Highly promising photoassisted reduction of nitrate has been also studied at mercury electrodes immersed in suspensions of semiconductor particles. − …”

“…10 Highly promising photoassisted reduction of nitrate has been also studied at mercury electrodes immersed in suspensions of semiconductor particles. [11][12][13] The first observation of the photoelectric effect at a metalelectrolyte interface is attributed to Becquerel, who in 1839 noted an electric current between two electrodes immersed in dilute acid solution when one of the electrodes was illuminated with light. 14 Following his observation, this effect was extensively studied and finally demonstrated to result from photoemission process (reviewed in ref 15).…”

Quantum Confinement Effects Enable Photocatalyzed Nitrate Reduction at Neutral pH Using CdS Nanocrystals

“…High nitrate levels promote the growth of algae, which upon its decay robs watersheds of the oxygen necessary for animal life. Unfortunately, nitrate has been found to be very stable chemically and difficult to reduce using unmodified electrodes even at very high overpotentials. , Electrocatalytic nitrate reduction has been achieved using electrodes modified with homogeneous catalysts, such as Co(III) or Ni(II) cyclams, Ru(II) bipyridine, Fe(III) porphyrin, and underpotential-deposited cadmium on gold. , Electrodes modified with nitrate reductase coupled to a number of electron-transferring dyes have also proven relatively effective. , Photosensitized nitrate reduction has been reported using metal porphyrins (quantum yield, Φ, equal to 5.3 × 10 -4 ), organic sensitizers ( N -methylphenothiazine and N , N , N‘ , N‘ -tetramethylbenzidine), TiO 2 (Φ = 0.005, Φ = 0.02), Pt−TiO 2 suspensions (Φ = 0.02), ZnS colloids (Φ = 0.013 and Pt-loaded Φ = 0.003), a variety of metal oxides (Φ = 0.006), and nitrate reductase coupled to an organic sensitizer (Ru(bpy) 3 2+ ) and methyl viologen (Φ = 0.08) . The highest quantum yield obtained in these studies used nitrate reductase as the catalyst …”

“…The highest quantum yield obtained in these studies used nitrate reductase as the catalyst , Since nitrate reduction becomes significantly more difficult with increasing pH, many of these studies did not report nitrate reduction at neutral pH or higher.…”