Highly Enhanced Photoelectrocatalytic Oxidation via Cooperative Effect of Neighboring Two Different Metal Oxides for Water Purification

Abstract

The generation of hydroxyl radicals derived from water molecules plays a pivotal role in attacking organic pollutants for the photoelectrocatalytic (PEC) process. To promote the generation efficiency of hydroxyl radicals, remarkably efficient transportation of the induced carriers and water molecules is desirable. Here, we implemented a remarkably enhanced photoelectrocatalytic oxidation via cooperative effect of neighboring two different metal oxides, Bi 2 MoO 6 and Sb-doped SnO 2 nanosheets, for water remediation. To realize the highly efficient transportation of the induced carriers, the hierarchical architecture Bi 2 MoO 6 wrapped Sb-doped SnO 2 nanosheets are rationally designed and synthesized. Density functional theory (DFT) calculations demonstrate that water molecules prefer to be adsorbed on the surface of Sb-doped SnO 2 nanosheets, producing hydroxyl radicals (•OH) on the surface of Bi 2 MoO 6 . The cooperation action between Bi 2 MoO 6 and Sb-doped SnO 2 nanosheets for the generation of hydroxyl radicals by water photoelectrolysis is enforced as follows: the Sb-doped SnO 2 nanosheet layer can act as the supply station of water and rapidly transfer the water molecules to neighboring Bi 2 MoO 6 to generate hydroxyl radical. This work may enlighten the design and construction of advanced photoanode materials for future scale-up of cost-effective water purification and environmental remediation.

Unveiling Hierarchical Dendritic Co3O4–SnO2 Heterostructure for Efficient Water Purification

“…To further confirm the charge transfer impedance of the as-prepared electrodes, electrochemical impedance spectroscopy (EIS) was performed with the help of a Nyquist plot (Figures c and S8 and Table S2). Ti/Co 3 O 4 –SnO 2 -168h showed a smaller arc radius with lower charge transfer resistance than other electrodes, thereby indicating Ti/Co 3 O 4 –SnO 2 -168h possesses a fast interfacial electron transfer rate. The photocurrent response (Figure d) showed an effective interfacial charge transfer and carrier separation of Ti/Co 3 O 4 –SnO 2 -168h compared with that of Ti/Co 3 O 4 –Sn 3 O 4 .…”

“…Typically, the flat-band potential ( E fb ) can be inferred from the Mott–Schottky plot, indicating that the E fb values for Co 3 O 4 and SnO 2 are −0.69 V (−0.45 V vs NHE) and −0.42 V (−0.18 V vs NHE), respectively. Note that the flat-band potential of n-type semiconductors is close to the bottom of the conduction band (CB), and the difference between the flat-band potential and the CB minimum is ∼0.2 eV . Thus, the corresponding E CB values for Co 3 O 4 and SnO 2 are −0.65 V (vs NHE) and −0.38 V (vs NHE).…”

“…To further confirm the charge transfer impedance of the as-prepared electrodes, electrochemical impedance spectroscopy (EIS) was performed with the help of a Nyquist plot (Figures 4c and S8 and Table S2). 54 80.3% after five cycles, thereby indicating an acceptable cyclability for industrial application. To fairly compare the previous reported data with the current electrode of Ti/ Co 3 O 4 −SnO 2 -168h, the low dye concentration of 20 mg/L was adopted since previous reports generally used dye concentrations of 20 mg/L or less (Table 1).…”

Designing advanced S‐scheme CdS QDs/La‐Bi2WO6 photocatalysts for efficient degradation of RhB

“…Although a single Bi 2 WO 6 exhibits an excellent visible light response, the problems of low carrier separation efficiency and high recombination efficiency significantly limit its photocatalytic degradation of pollutants. [29] Element-doping [30] and constructing heterostructures [31,32] are general strategies to enhance the photocatalytic performance of a single catalyst. For instance, Lee et al [33] studied Eu 3+ doping on the photodegradation efficiency of Bi 2 WO 6 samples.…”

“…[36] Thus, constructing heterojunctions can effectively accelerate the separation and transfer of photocarriers. [31,37] For instance, semiconductor quantum dots ( QDs) due to their unique zero-dimensional structure, many scholars have applied their to construct heterojunctions, such as CdS, [38] CdSe, [39] and PbSe. [40] These QDs combined with TiO 2 as heterostructures effectively improve the photocurrent response of intrinsic TiO 2 and show good photocatalytic ability.…”