Photoelectrochemical properties of hematite thin films grown by MW-CBD

CVD Growth of Hematite Thin Films for Photoelectrochemical Water Splitting: Effect of Precursor-Substrate Distance on Their Final Properties

“…The obtained values are summarized in Table 1 . All values are within the usually reported range of 1.9–2.2 eV [ 7 , 8 , 10 , 13 , 22 , 34 , 36 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ].…”

“…In both cases, the corresponding E g is obtained by extrapolating the linear fitting from the plot and finding the energy value where this linear fitting intersects the zero line. The lowest bandgap of α-Fe 2 O 3 is usually reported to be around 1.9–2.2 eV [ 7 , 8 , 10 , 13 , 22 , 34 , 36 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. However, while many authors address the corresponding transition to be indirect [ 13 , 44 , 46 , 47 , 54 ], others found direct transitions corresponding to the same edge [ 7 , 22 , 34 , 49 , 51 , 53 ].…”

“…The lowest bandgap of α-Fe 2 O 3 is usually reported to be around 1.9–2.2 eV [ 7 , 8 , 10 , 13 , 22 , 34 , 36 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. However, while many authors address the corresponding transition to be indirect [ 13 , 44 , 46 , 47 , 54 ], others found direct transitions corresponding to the same edge [ 7 , 22 , 34 , 49 , 51 , 53 ]. As a way of comparing the results to previous works, several authors report both direct and indirect E g values from different linear fittings made in the same spectral regions [ 8 , 50 ].…”

“…Unfortunately, because hematite presents a weak optical absorption coefficient, small carrier mobility, and a short hole diffusion length, the illuminated hematite electrodes normally exhibit poor efficiency as photoanodes in water oxidation [ 5 , 6 ]. However, many studies have indicated that nanocrystalline morphology could be one way to overcome those limitations and increase the photon-to-current yield by minimizing the distance that minority carriers must diffuse before reaching the interface and contacts [ 1 , 7 , 8 , 9 , 10 ]. In addition, the large surface area exhibited by the nanostructured semiconductors is important in photoelectrochemical devices due to the large number of catalytic sites [ 3 , 7 , 11 , 12 , 13 ].…”

“…However, many studies have indicated that nanocrystalline morphology could be one way to overcome those limitations and increase the photon-to-current yield by minimizing the distance that minority carriers must diffuse before reaching the interface and contacts [ 1 , 7 , 8 , 9 , 10 ]. In addition, the large surface area exhibited by the nanostructured semiconductors is important in photoelectrochemical devices due to the large number of catalytic sites [ 3 , 7 , 11 , 12 , 13 ]. Additionally, the nano structuration facilitates the incorporation of other nanomaterials or atoms that improve the catalytic performance [ 14 , 15 , 16 , 17 , 18 ].…”