Single Precursor Mediated-Synthesis of Bi Semimetal Deposited N-Doped (BiO)₂CO₃ Superstructures for Highly Promoted Photocatalysis

Visible light utilization and charge separation efficiency are the two dominant factors for development of efficient visible light photocatalysts. In this work, visible light response N-doped (BiO) 2 CO 3 and non-noble Bi semimetal-deposited N-doped (BiO) 2 CO 3 superstructures were prepared by direct hydrothermal treatment of a single precursor (ammonium bismuth citrate) at different temperatures. The atomic utilization efficiency of the precursor was increased as all the components in the material were derived from this single precursor. Density functional theory calculations combined with systematical characterization results revealed that N atoms were in situ doped into (BiO) 2 CO 3 lattice by substituting O atoms in (BiO) 2 2+ layers. The upward shift of valence band top, originating from the hybridization of N 2p states with Bi 6s+6p and O 2p orbital, led to narrowed bandgap of (BiO) 2 CO 3 . Under higher hydrothermal temperature, Bi decorated N-doped (BiO) 2 CO 3 superstructures were produced as Bi 3+ ions can be reduced to Bi 0 semimetal by citrate ions. For N-doped (BiO) 2 CO 3, N-doping could narrow the bandgap of (BiO) 2 CO 3 and then boost the visible light absorption. In terms of Bi decorated N-doped (BiO) 2 CO 3, except for more absorption in the visible region, the plasmonic effect of the in situ formed Bi nanoparticles could accelerate the separation and transfer of photogenerated carriers, and thus more active species (hydroxyl radicals) were generated. With N-doped (BiO) 2 CO 3 as photocatalysts, NO can be efficiently removed under visible light irradiation. Significantly, the Bi deposited N-doped (BiO) 2 CO 3 with excellent stability showed much higher activity than N-doped (BiO) 2 CO 3 . This work encourages us to search for green methods to synthesize highly efficient photocatalysts, which also provides a strategy to enhance the photocatalytic performance via combination of nonmetal doping and non-noble metal deposition.