Reaction between nickel hydroxide and cerium(IV) ammonium nitratein aqueous solution

Cerium(IV) ammonium nitrate (CAN) has been extensively used as a sacrificial oxidantto study water-oxidation catalysts (WOCs). Although nickel hydroxide has been extensivelyinvestigated as WOCs, water-oxidation reaction (WOR), and mechanistic studies in thepresence of CAN and nickel hydroxide were rarely performed. Herein, using in situ Ramanspectroscopy, in situ X-ray absorption spectroscopy, and in situ electron paramagneticresonance, WOR in the presence of CAN and β-Ni(OH)۲ was investigated. As a WORmechanism, it is proposed that β-Ni(OH)۲ in the presence of CAN is oxidized to α-NiO(OH).α-NiO(OH) in the presence of acidic conditions evolves oxygen and is reduced to Ni(II). Inother words, the role of β-Ni(OH)۲ is the storage of four oxidizing equivalents by CAN, andthen a four-electron reaction could result in WOR with low activation energy. In contrast toβ-Ni(OH)۲, Ni(OH۲)۶۲+ (aq) could not be oxidized to α-NiO(OH).

کلیدواژه ها:

Cerium(IV) Ammonium Nitrate ، Mechanism ، Nickel Hydroxide ، Oxygen ، WateroxidationReaction