Bi/Bi₂Ce₂O₇ heterojunctions for visible-light photocatalytic nitrogen fixation: Synergistic enhancement by localized...

Metallic bismuth exhibits unique localized surface plasmon resonance (LSPR) and persistent catalytic activity, due to effective absorption in the UV-visible region that can trigger LSPR and promote the separation of photogenerated charge carriers, leading to efficient photocatalysis. In this study, Bi/Bi₂Ce₂O₇ (Bi/BCO) heterojunctions are in situ constructed via hydrothermal treatment of cerium(III) chloride and bismuth(III) chloride in the presence of a calculated amount of mannitol. Among the series, Bi/BCO-2, prepared with a 4 mmol feed of mannitol, exhibits the greatest photocurrent under visible light irradiation, which is 18 times that of Bi₂Ce₂O₇ (BCO) prepared in the absence of mannitol. In photocatalytic nitrogen fixation, the Bi/BCO-2 sample achieves the highest ammonium generation rate of 248.4 μmol g^-1 h^-1, 49 times greater than that of BCO. This is accounted for by the in situ formation of metallic Bi on BCO, where the LSPR effect, in synergy with oxygen vacancies in BCO, facilitates the adsorption and activation of nitrogen and intermediates and reduces the energy barriers of key steps in the catalytic reduction of nitrogen to ammonia.