Large dipole moment induced efficient bismuth chromate photocatalysts for wide-spectrum driven water oxidation and complete mineralization of pollutants

Abstract

Herein, a wide-spectrum (∼678 nm) responsive Bi8(CrO4)O11 photocatalyst with a theoretical solar spectrum efficiency of 42.0% was successfully constructed. Bi8(CrO4)O11 showed highly efficient and stable photocatalytic water oxidation activity with a notable apparent quantum efficiency of 2.87% (420 nm), superior to many reported wide-spectrum driven photocatalysts. Most remarkably, its strong oxidation ability also enables the simultaneous degradation and complete mineralization for phenol, and its excellent performance is about 23.0 and 2.9 times higher than CdS and P25-TiO2, respectively. Its high activity is ascribed to the giant internal electric field induced by its large crystal dipole, which accelerates the rapid separation of photogenerated electron–hole pairs. Briefly, the discovery of wide-spectrum bismuth chromate and the mechanism of exponentially enhanced photocatalytic performance by increasing the crystal dipole throw light on improving solar energy conversion.

Schottky Barrier‐Induced Surface Electric Field Boosts Universal Reduction of NOx− in Water to Ammonia

“…À anions on Ni 35 /NC-sd catalyst, the surface charges of various Ni x /NCsd samples are carefully analyzed using Kelvin probe force microscopy techniques (Figure 3 a). [10] With similar heights (Figure S18), the Ni 35 /NC-sd with more Ni/NC heterojunctions integrated inside exhibits more negative the contact potential difference (DV) between the Si substrate and the sample (À0.148 V), which is two times of the value of Ni 14 /NC-sd sample (Figure 3 b). It is reasonable that merging more Ni/ NC heterojunctions into one sample enlarges the negatively charged surface field located on the carbon support via accepting more electrons from the Ni nanoparticle-based electron donors as already demonstrated in Figure 1 f and 2 c.…”

Photocatalytic activity enhanced via surface hybridization

“…Our group found that in the bismuth iodide series photocatalyst, the reduction in the content of iodine element that contributes to the valence band maximum (VBM) composition significantly shifts the position of the VBM, thereby obtaining enhanced oxidation capacity 16 . In addition, we also found that the contribution of chromium element make the VB and CB positions of Bi 8 (CrO 4 )O 11 move down directly promote the oxidation capacity and narrow the band gap, thereby completely mineralized phenol into CO2 and response wide spectral absorption 77 …”

“…16 In addition, we also found that the contribution of chromium element make the VB and CB positions of Bi 8 (CrO 4 )O 11 move down directly promote the oxidation capacity and narrow the band gap, thereby completely mineralized phenol into CO2 and response wide spectral absorption. 77 From macro perspective, one considerable factor is the appropriate size of the inorganic material. If the particle size is too large, the charge separation efficiency will be reduced.…”

Efficient Mineralization of Organic Pollutants Using Visible-light-induced PTCDA Anions Electronic Reservoir and Photogenerated Holes

“…Since visible light accounts for ~ 45% of the total radiant energy of sunlight, a wide-spectrum response is particularly important 31 . Contributed by the π-π accumulation induced extended conjugated electron cloud, the edge of the intrinsic absorption band of PTCDA covers the entire visible range of 630nm, further calculating the bandgap of 1.97ev, the position of CB and VB is -0.33V and 1.64V, respectively (Figure S10).…”