Understanding the composition and electronic structure dependent photocatalytic performance of bismuth oxyiodides

Abstract

1 A series of bismuth oxyiodides were obtained by calcining the precursor compound (Bi7O9I3). Their 2 compositions and electronic structures were analyzed by various physicochemical characterizations, 3 slurry method measurements and theoretic calculations. Iodine vacancies appearing at elevated 4 temperatures before the phase transition contribute to the increased photocatalytic activity, which can 5 be attributed to the increase of band gaps, downward shifts of band potentials and the change of 6 semiconductor behavior from p type toward n type. The catalyst obtained at 400 °C displayed an 7 excellent photocatalytic performance for phenol degradation, and it was characterized as a composite 8 of two components with well-matched band potentials and well contact interfaces. Photogenerated 9 holes were revealed as the main active species in the phenol degradation. This study could bring 10 insights in the fabrication of novel high efficient bismuth oxyiodide composites by simultaneously 11 controlling the extent of phase transition and the amount of iodine vacancies.12 13

Photocatalytic BiOX Mortars under Visible Light Irradiation: Compatibility, NOx Efficiency and Nitrate Selectivity

“…In the first instance, the position and intensity of the diffraction lines were modified. The characteristic peak of BiOI for the 110-plane decreased significantly, and peaks corresponding to Bi2O3 and Bi5O7I in the BiOI-pore sample appeared [40][41][42]. The transformation of BiOI in these Ideficient bismuth oxyiodide compounds in alkaline pH conditions is consistent with previous reports [41,43].…”

Room Temperature Synthesis of BiOI/Bi5O7I p–n Heterojunction with Enhanced Photocatalytic Activity for 17α‐Ethynylestradiol

“…The XPS survey spectrum in Figure a reveals that the composite is mainly composed of Bi, O, I, and C elements (C element came from the reference sample). In Figure b, the peaks at about 164 eV and 159 eV are observed, which could be ascribed to Bi 4f 5/2 , and Bi 4f 7/2 , respectively . Those peaks at 164.7 eV and 159.4 eV or 164.4 eV and 159.1 eV are assigned to Bi 3+ in BiOI or Bi 5 O 7 I.…”

Influence of the Chemical Compositions of Bismuth Oxyiodides on the Electroreduction of Carbon Dioxide to Formate

“…The powder X‐ray diffraction (XRD) patterns of all bismuth oxyiodides are shown in Figure . For three catalysts, α‐Bi 5 O 7 I, Bi 7 O 9 I 3 , and BiOI are identified according to the standard PDF cards (α‐Bi 5 O 7 I PDF#: 97‐041‐1666, Orthorhombic, Ibca; BiOI PDF#: 97‐039‐1354, tetragonal, P 4 /nmm) and the literature . Distinct differences are observed between the patterns of BiOI and those of Bi 7 O 9 I 3 and Bi 5 O 7 I. Interestingly, the peak position at 29.8° of BiOI notably shift in the negative direction to 29.0° of Bi 7 O 9 I 3 and 28.2° of Bi 5 O 7 I, respectively, which is attributed to the expansion of lattice and structural distortion, owing to the variability of oxygen and bismuth in different chemical compositions .…”

“…They are composed of [Bi x O y ] layers interleaved with iodide [I z ] layers via van der Waals forces . Up to now, all bismuth oxyiodides with varied chemical compositions include BiOI, Bi 7 O 9 I 3 , α‐Bi 5 O 7 I, β‐Bi 5 O 7 I, Bi 4 O 5 I 2 and Bi 3 O 5 I 2 . So far, the literature on bismuth oxyiodides electrocatalysts for CO 2 RR especially is still scarce, and the detailed influence of chemical compositions on the electrocatalytic performances is obscure.…”