Tantalum Nitride Nanorod Arrays: Introducing Ni–Fe Layered Double Hydroxides as a Cocatalyst Strongly Stabilizing Photoanodes in Water Splitting

Abstract

Ta3N5 nanostructures are widely explored as anodes for photoelectrochemical (PEC) water splitting. Although the material shows excellent semiconductive properties for this purpose, the key challenge is its severe photocorrosion when used in typical aqueous environments. In the present work we introduce a NiFe layered double hydroxide (LDH) cocatalyst that dramatically reduces photocorrosion effects. To fabricate the Ta3N5 electrode, we use through-template anodization of Ta and obtain oxide nanorod arrays that then are converted to Ta3N5 by high temperature nitridation. After modification with our cocatalyst system, we obtained solar photocurrents of 6.3 mA cm–2 at 1.23 VRHE in 1 M KOH, and an electrode maintains about 80% of the initial activity for extended irradiation times.

Promoting charge carrier utilization by integrating layered double hydroxide nanosheet arrays with porous BiVO4 photoanode for efficient photoelectrochemical water splitting

“…After the decoration of NiFe-LDH nanosheet arrays as OEC layer, the BiVO4/NiFe-LDH photoanode exhibits significant improvement of back-side illumination photocurrent, reaching an AM 1.5G photocurrent of 4.02 mA cm −2 at 1.23 V vs. RHE, which is 2.8 times higher than that of the pristine BiVO4. This value is higher than other OECs decorated on un-doped BiVO4 (Table S2) and some photoanodes decorated with NiFe-LDH as OECs, e.g., NiFe-LDH/Ta3N5 (1.7 mA cm −2 at 1.23 V vs. RHE) [26], TiO2/rGO/NiFe-LDH (1.74 mA cm −2 at 1.245 V vs. RHE) [5], Mn-doping Fe2O3/NiFe-LDH (ca. 2.1 mA cm −2 at 1.23 V vs. RHE) [9], quantum dot/LDH/BiVO4 (2.23 mA cm −2 at 1.23 V vs. RHE) [17].…”

“…They may serve as promising OEC candidates for PEC water splitting. Nowadays, they have been applied to some potential photoanodes, including TiO2 [5], Fe2O3 [9], TaN3 [26], which have shown enhanced performances in both onset potentials and photocurrent densities. In addition, the LDHs are synthesized simply and grow on substrate easily in the form of nanostructure [22].…”

Rational Design and Construction of Cocatalysts for Semiconductor‐Based Photo‐Electrochemical Oxygen Evolution: A Comprehensive Review

“…[196] Copyright 2018, American Chemical Society. Nowadays, the most commonly used LDH is NiFe-LDH, as Ni and Fe are both earth-abundant and it shows the best catalytic activity among the Ni-based LDH, which was reported by Diaz-Morales et al [189] They have been applied to some potential metal-based photoanodes including Ta 3 N 5 , [190] BiVO 4 , [191,192] WO 3 , [193] α-Fe 2 O 3 , [194] and have shown promoted performance in onset potentials, photocurrent densities, as well as photostability. Reproduced with permission.…”

Solar fuel production: Strategies and new opportunities with nanostructures

“…Apart from high solar energy conversion efficiency, another indispensable requirement for the practical implementation of solar fuel production is long-term material durability [3,35,36]. This requirement has disappointed the use of narrow band-gap semiconductors possessing suitable band structures for efficient solar-to-fuel conversion, because these semiconductors suffer from photo(electro)chemical corrosion or passivation when operating in aqueous electrolytes.…”