Enhanced Charge Transport and Increased Active Sites on α-Fe₂O₃ (110) Nanorod Surface Containing Oxygen Vacancies for Improved Solar Water Oxidation Performance

Abstract

The effect of oxygen vacancies (V O ) on α-Fe 2 O 3 (110) facet on the performance of photoelectrochemical (PEC) water splitting is researched by both experiments and density functional theory (DFT) calculations. The experimental results manifest that the enhancement in photocurrent density by the presence of V O is related with increased charge separation and charge-transfer efficiencies. The electrochemical analysis reveals that the sample with V O demonstrates an enhanced carrier density and reduced charge-transfer resistance. The results of DFT calculation indicate that the better charge separation is also contributed by the decrease of potential on the V O surface, which improves the hole transport from the bulk to the surface. The reduced charge-transfer resistance is owing to the greatly increased number of active sites. The current study provides important insight into the roles of V O on α-Fe 2 O 3 photoanode, especially on its surface catalysis. The generated lesson is also helpful for the improvement of other PEC photoanode materials.

Structure, Defects, and Magnetism of Electrospun Hematite Nanofibers Silica-Coated by Atomic Layer Deposition

“…Both oxygen vacancies ( V O s), the main native point defects in hematite, − and dislocations lead to broadening of the Raman lines. , However, in the case of dislocations, the peaks shift toward higher frequencies with respect to defect-free hematite and the shift increases with increasing dislocation density . On the contrary, in the case of V O s, the self-doping of α-Fe 2 O 3 surface due to the close Fe 2+ -sites , causes the peaks to shift toward lower frequencies …”

The role of oxygen vacancies in water splitting photoanodes

“…The enhanced performance of hematite photoanodes aer N 2 treatments has also been reported. 93 The experimental results showed that the enhanced performance induced by the presence of OVs was related to an increase of both charge separation and charge transfer efficiencies. Combining these experimental results with DFT calculations, it was found that the enhanced charge separation was achieved by the increased electron density combined with a decrease in the surface potential which improves the hole transport from the bulk to the (110) surface.…”

Recent Development in Defects Engineered Photocatalysts: An Overview of the Experimental and Theoretical Strategies

“…[18][19][20] Alternatively, effective light absorption with undoubtedly decreased recombination and improved photocatalytic performance through defect engineering have been reported. [21,22] Defects in semiconductors greatly alter carrier concentration and interface reaction affecting the overall process efficiency of a photocatalyst. Thus, defects are the most frequently investigated scenario for tuning the properties of photocatalyst.…”