Substitution Boosts Charge Separation for High Solar-Driven Photocatalytic Performance

Abstract

Bandgap engineering of photocatalysts is a common approach to achieving high effective utilization of solar resource. However, the difficulty in achieving bandgap narrowing and high activity simultaneously seems to be irreconcilable via the traditional modification pathway. Herein, we have substituted iodine for a fraction of bromine atoms in BiOBr to overcome this restriction and provided some deep-seated insights into how the substitution boosts the photocatalytic properties. The substituted BiOBr 0.75 I 0.25 exhibited exceptional photoactivity, with photon-to-current conversion efficiency approximately 6 times greater than TiO 2 in UV region, and more than 10 times higher than BiOBr or BiOI in visible-light region. We found that the substitution narrowed the bandgap, facilitated the diffusion of electron with small effective mass, as well as induced oxygen vacancies on [Bi 2 O 2 ] 2+ layers. By virtue of the stronger dipole moments produced, the enhancement of intrinsic electric fields between [Bi 2 O 2 ] 2+ and halogen slabs was achieved in BiOBr 0.75 I 0.25 ; thereby the distance the photogenerated electron could diffuse was sufficient to inhibit the recombination. Our findings not only shed light on the potential properties of hybrid-halide photocatalysts but also provide a strategy for developing high efficiency catalysts.

Bi5+, Bi(3−x)+, and Oxygen Vacancy Induced BiOClxI1−x Solid Solution toward Promoting Visible‐Light Driven Photocatalytic Activity

“…[23,24] d) Facet-controlled fabrication; [25][26][27] It has been demonstrated that exposed {0 01}f acets could enhance the thermodynamic stabilitya nd photogenerated electron-hole pairs separation efficiency of BiOCl. [26] f) Solid solution of BiOCl x Br 1Àx , [28][29][30][31] BiOBr x I 1Àx , [32,33] andB iOCl x I 1Àx . [22,34,35] The BiOBr x I y solid solution exhibits an arrow band gap and promotes the diffusion of electrons and inhibition of photogenerated electrons and hole recombination.…”

“…f) Solid solution of BiOCl x Br 1− x , BiOBr x I 1− x , and BiOCl x I 1− x . The BiOBr x I y solid solution exhibits a narrow band gap and promotes the diffusion of electrons and inhibition of photogenerated electrons and hole recombination . e) Crystal defect structure; The crystal defects can be considered as active sites, which not only enhance the adsorption capacity but also narrow the band gap for photocatalysts.…”

Mechanochemical Synthesis of Nitrogen-Deficient Mesopore-Rich Polymeric Carbon Nitride with Highly Enhanced Photocatalytic Performance

“…57,58 The τ 1 , τ 2 , and τ 3 of CN-MA400m are all longer than those of CN (Figure 5d), and the prolonged τ 1 is ascribed to the generated single nitrogen vacancies in the bulk of CN-MA400m, while the prolonged τ 2 may result from the formed surface vacancy clusters. 57,59,60 The I 1 − I 3 reflect the relative concentrations of vacancies or defects. The I 3 of both CN and CN-MA400m approaches zero, suggesting few large voids in the samples.…”

Z-scheme CdS/BiVO4 Photocatalyst for Highly Efficient Photodegradation of Organic Pollutants and DFT Calculation

“…Among them, Nd and C are the carrier density and interface capacitance, e0 is the amount of charge carried by an electron, ε is the dielectric constant, ε0 is vacuum permittivity and, V is the applied voltage [45]. According to calculations, the carrier densities of BiVO4, CV-x (x=1~4) and CdS are 2.92×10 23 , 7.08×10 24 , 9.64×10 24 , 1.55×10 25 and 9.46×10 23 and 6.04×10 24 cm -3 , respectively.…”