Conduction and Valence Band Positions of Ta₂O₅, TaON, and Ta₃N₅ by UPS and Electrochemical Methods.

Abstract

The band gap positions of the title compounds are determined by electrochemical analysis and UV photoelectron spectroscopy (UPS). The conduction band positions of the compounds are largely similar, whereas the valence band positions vary significantly (Ta 2 O 5 < TaON < Ta 3 N 5 ). The results indicate that TaON and Ta 3 N 5 are potential photocatalysts for overall water splitting utilizing solar radiation. The results of UPS are in good agreement with the electrochemical analysis, demonstrating that UPS is a reliable alternative method of determining the band positions of a wide range of photocatalytic materials. -(CHUN, W.-J.; ISHIKAWA, A.; FUJISAWA, H.; TAKATA, T.; KONDO, J. N.; HARA, M.; KAWAI, M.; MATSUMOTO, Y.; DOMEN*, K.; J.

Coupling of narrow and wide band-gap semiconductors on uniform films active in bacterial disinfection under low intensity visible light: Implications of the interfacial charge transfer (IFCT)

“…The root mean square (rms) roughness for the samples TaON and TaON/Ag were respectively 2.2 and 2.7 nm. An increase in roughness leads to higher contact angle reducing the polarity and the total surface energy [23]. Increased sample rugosity allows for a better adhesion of the Ag-ions responsible for the bacterial inactivation (see Section 3.6).…”

“…The TaON spectral deconvolution of shows a peak at 24.2 eV for TaON and another peak for Ta 2 O 5 at 25.9 eV, and was carried out by means of the CasaXPS-Vision 2 software. Recently, Chun et al [23] demonstrated that TaON and Ta 2 O 5 are stable species able to carry oxidation/reduction reactions under visible light. Fig.…”

“…8, a mechanism for electron injection for the charge transfer from Ag 2 O into Ta 2 O 5 is suggested. This mechanism considers the potential energy of the semiconductor bands [23]. When the sputtered Ag layer is exposed to air, the water vapor in the air leads to the formation of surface AgOH.…”

Establishing Efficient Cobalt-Based Catalytic Sites for Oxygen Evolution on a Ta3N5 Photocatalyst

“…1,4 Among the photocatalysts investigated to date, tantalum(V) nitride (Ta 3 N 5 ) has emerged as one of the most promising candidates and has been extensively investigated for more than a decade. [4][5][6][7][8][9][10][11][12][13][14][15] Ta 3 N 5 has a visible-light response (approximately 600 nm, ~2.1-eV band gap) and is capable of producing hydrogen or oxygen in the presence of appropriate sacrificial reagents and surface modifications under visible-light irradiation. 1,[5][6][7][8][9][10][11][12][13][14][15][16] Our recent work on Ta 3 N 5 thin films for the photoelectrochemical oxygen evolution reaction (OER) noted that despite having suitable absorption in the visible-light range, Ta 3 N 5 suffered from very low transport properties and fast carrier recombination (<10 ps) without any surface decoration.…”

Surface Modification of TaON with Monoclinic ZrO2 to Produce a Composite Photocatalyst with Enhanced Hydrogen Evolution Activity under Visible Light

“…5,6 In particular, this material is a promising candidate as an overall water-splitting photocatalyst to produce clean hydrogen fuel, due to its suitable band-edge position 7 and stability in aqueous media 8 and under photoirradiation. 2a However, a major drawback of TaON as a photocatalyst is its low activity for water reduction (i.e.…”