Nitrogen-Doped In₂O₃ Thin Film Electrodes for Photocatalytic Water Splitting

Abstract

New visible-light photocatalysts were prepared by doping In2O3 with nitrogen from ethylenediamine (NH2(CH2)2NH2) or ammonium chloride (NH4Cl) as the nitrogen source. Nitrogen-doped In2O3 powder prepared from NH2(CH2)2NH2 shows a rhombic structure and a substitutional N-doping, while the powder prepared from NH4Cl shows a cubic structure and NH x in interstitial sites. N-doping extended the light absorption of In2O3 to the visible region (λ < ∼650 nm), narrowing the band gap from 3.5 eV to approximately 2.0 eV. The photocurrent densities of N-doped In2O3 electrodes are at least double those of undoped In2O3 and approximately 50 times better than N-doped TiO2 electrodes in the visible region, although optimization will be needed to deliver high photocurrents. This present work shows that In2O3 can be suitably doped to produce a promising photocatalyst with improved photoelectrochemical properties for solar hydrogen conversion applications.

Photocatalytic production of hydrogen on Ni/NiO/KNbO3/CdS nanocomposites using visible light

“…However, the majority of the simple and mixed-metal oxides photocatalysts are primarily active for H 2 production under UV irradiation (l < 385 nm or E g $ 3.0 eV) present in only a small portion of solar light. More recently, there is a focused effort on the development of photocatalysts that are capable of using visible light (l ¼ 400-700 nm) for the photocatalytic production of H 2 including transition metal doping (e.g., platinum, 29 chromium, 30 and vanadium 31 ) and nonmetallic element doping (e.g., nitrogen, [32][33][34][35] sulfur, 36,37 and carbon 35,38 ). CdS, n-type semiconductor with E g ¼ 2.4 eV, has been shown to have photocatalytic activity for H 2 production under visible light irradiation, although, sacrificial electron donors such as C 2 H 5 OH, 39 HS À , 40,41 or SO 3 2À 19 are used to obtain measurable rates of H 2 production and to avoid the photocorrosion of CdS in the presence of O 2 .…”

Titanium–indium oxy(nitride) with and without RuO2 loading as photocatalysts for hydrogen production under visible light from water

“…These results are close to the reported values for bulk InN (444.3 eV). [7,13] Therefore, XPS further confirms the formation of InN.…”

“…[6] thin film electrodes are effective for photocatalytic water splitting. [7] Therefore, it may be possible to combine the TiO 2 property of formation of electrons and holes by absorbing light and then using the interconnection between TiO 2 and In 2 O 3 to transfer the holes to In 2 O 3 . Moreover, the nitrided treatment of a mixture of titanium oxide and indium oxide may be effective to enhance absorption of visible light.…”

The search for efficient electrocatalysts as counter electrode materials for dye-sensitized solar cells: mechanistic study, material screening and experimental validation

“…123,124 In the study on DSCs, conductive oxides are primarily used as a conducting support for electrocatalytically active materials (for example, Pt) to facilitate a faster electron transfer throughout the external circuit. Unfortunately, a few conductive oxides, such as indium oxide (In 2 O 3 ), stannic oxide (SnO 2 ) and zinc oxide (ZnO), were tested to be catalytically inactive toward the triiodide reduction reaction because of their low-adsorption energy and limited number of active sites.…”