Enhanced Water‐Splitting Performance of Perovskite SrTaO₂N Photoanode Film through Ameliorating Interparticle Charge Transport

Abstract

Here SrTaO2N has been found to exhibit photoelectrochemical water splitting, with a theoretical solar‐to‐hydrogen efficiency of 14.4%. Ameliorating the interparticle charge transport by H2 annealing, the solar photocurrent of the SrTaO2N(H) granular film at 1.23 V versus reversible hydrogen electrode (RHE) is increased by ≈250% in comparison with the SrTaO2N film. Using an aberration corrected scanning transmission electron microscope and super‐X energy dispersive spectroscopy, the atomic scale observation has proved a decrease of oxygen concentrations in the surface of SrTaO2N(H) particle, which may allow its electrical conductivity to be increased from 0.77 × 10−6 to 2.65 × 10−6 S cm−1 and therefore the charge separation efficiency has been greatly increased by ≈330%. After being modified by Co–Pi water oxidation catalyst, the SrTaO2N(H) photoanode shows a solar photocurrent of 1.1 mA cm−2 and an incident photo‐to‐current efficiency value of ≈20% at 400–460 nm and 1.23 V versus RHE, which suggests that it is a new promising photoanode material for solar water splitting.

Efficient Solar‐Driven Water Oxidation over Perovskite‐Type BaNbO2N Photoanodes Absorbing Visible Light up to 740 nm

“…[9] The Ba-rich composition of Ba 5 Nb 4 O 15 lowers the potential for the reduction of Nb ions during nitridation, although the nonstoichiometric Ba-to-Nb ratio results in amorphous surface of BaNbO 2 N particles. [11,12] Such annealing decreases the oxygen concentration on the surfaces of SrTaO 2 N photoanodes, thus improving the interface charge transfer efficiency. [5,10] For this reason, heat treatment after nitridation is required in order to modify the surface properties of the oxynitride.…”

“…[7] Surface treatment with distilled water or acids after nitridation has been found to have a minimal effect in terms of improving the photocurrent in this material during water oxidation. [12] It is therefore expected that a similar annealing treatment would also upgrade the PEC water oxidation activity of BaNbO 2 N photoanodes. Annealing in H 2 has been shown to improve the PEC photoactivity of Ta-based oxynitride electrodes.…”

Defective Bi2WO6‐Supported Cu Nanoparticles as Efficient and Stable Photoelectrocatalytic for Water Splitting in Near‐Neutral Media

“…To determine the reasons for improved performance of Vo‐Bi 2 WO 6 and Cu/Bi 2 WO 6 ‐x (x=1, 2) photoanodes, the water oxidation photocurrent is written as the product of theoretical maximum photocurrent (J max ), the light harvesting efficiency (η abs ), the charge separation efficiency (η sep ), and the interfacial charge transfer efficiency (η int ) as the following equation …”

“…Therefore a highly efficient photoelectrocatalyst is required to improve reaction rate of the water splitting process. Since the study of PEC water splitting, many semiconductor photoelectrocatalyst materials have received extensive attention, such as TiO 2 , BiVO 4 , and SrTaO 2 N . Among these oxide metal semiconductors, Bi 2 WO 6 is still remains the most promising catalyst owing to its non toxicity and higher photo stability.…”

Perovskite Sr1−x Ba x W1−y Ta y (O,N)3: synthesis by thermal ammonolysis and photocatalytic oxygen evolution under visible light

“…As the nitrogen content of SrW(O,N) 3 3 crystal structures contain strontium tantalum oxynitride as a secondary phase. As is known, the strontium tantalum oxynitride has the photocatalytic activity for water oxidation half-reaction under visible light irradiation [46]. Possibly, the secondary phase can provide a positive effect on the O 2 evolution reaction.…”