Efficient Water Oxidation Using Ta₃N₅Thin Film Photoelectrodes Prepared on Insulating Transparent Substrates

Abstract

Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Recent Developments in Visible‐Light‐Absorbing Semitransparent Photoanodes for Tandem Cells Driving Solar Water Splitting

“…The most negative onset potential for the OER is ≈0.3 V versus reversible hydrogen electrode (RHE) when transparent BiVO 4 is used, [ 25,28,29 ] and 0.5–0.7 V versus RHE when transparent Fe 2 O 3 or Ta 3 N 5 is used. [ 9,14,39 ] In particular, the values of the onset potential for Ta 3 N 5 are far from the expected value. In addition, the long‐term stability of photoanodes during the water‐splitting reaction is also an important issue for efficient, durable water splitting by a tandem cell.…”

“…In 2020, Higashi and colleagues reported a transparent Ta 3 N 5 photoanode prepared directly on SiO 2 insulating substrates. [ 39 ] Generally, semiconductor‐based photoelectrodes have been fixed on an appropriate metal or TCO layer as the back contact to collect the electrons or holes. However, the reported transparent Ta 3 N 5 /SiO 2 photoanode exhibited OER without the introduction of a TCO layer.…”

“…[10] In addition to oxide materials, Ta 3 N 5 -based photoanodes with an absorption edge wavelength of 600 nm and a suitable band-edge position for water splitting have been considered as one of the leading candidates to realize highly efficient PEC water splitting. [9,[37][38][39][40][41][42][43][44][45][46][47][48][49][50] Ta 3 N 5 thin-film photoanodes fabricated on transparent conductive substrates are found to be potentially applicable to the front-side photoelectrode in a tandem cell. [9,38,48] In 2019, Higashi et al reported a tandem cell composed of a NiFeO x electrocatalyst-modified Ta 3 N 5 transparent photoanode fabricated on n-type GaN-coated sapphire (Ta 3 N 5 /GaN/Al 2 O 3 ) on the front side and two-series-connected CuInSe 2 elements terminated with a Pt electrode on the back side, which achieved overall water splitting with an STH efficiency of 7.0% in the initial stage of the reaction.…”

Design Predictions of n–n Heterojunction Based Photoanode for Efficient Unbiased Overall Solar Water Splitting

“…[12] There are a limited number of candidate materials with suitable band positions and bandgaps for zero-bias overall water splitting. [13] In recent years, tantalum nitride (Ta 3 N 5 ) has become a leading candidate [14][15][16][17][18] because it can absorb visible light over a wide range of wavelengths of up to 600 nm, [19] and its band position is suitable for overall water splitting. Moreover, the Fermi level of Ta 3 N 5 was estimated as À0.2 V versus a standard hydrogen electrode (SHE), [20] indicating that Ta 3 N 5 could potentially exhibit a negative onset potential DOI: 10.1002/ente.202100570 There are multiple requirements for maximizing the efficiency of photoelectrochemical overall water splitting using a single n-type semiconducting photoanode.…”

Semi-transparent quaternary oxynitride photoanodes on GaN underlayers

“…The photocurrent is lower than other reported semitransparent Ta 3 N 5 film because of smaller thickness and smaller amount of N incorporation. [15][16][17] The photocurrent maintained stable during chronoamperometry (CA) (Fig. S5, ESI †).…”