Co₃O₄ Nanoparticles as Robust Water Oxidation Catalysts Towards Remarkably Enhanced Photostability of a Ta₃N₅ Photoanode

Abstract

Despite the fact that Ta3N5 absorbs a major fraction of the visible spectrum, the rapid decrease of photocurrent encountered in water photoelectrolysis over time remains a serious hurdle for the practical application of Ta3N5 photoelectrodes. Here, by employing a Co3O4 nanoparticle water oxidation catalyst (WOC) as well as an alkaline electrolyte, the photostability of Ta3N5 electrode is significantly improved. Co3O4/Ta3N5 photoanode exhibits the best durability against photocorrosion to date, when compared with Co(OH)x/Ta3N5 and IrO2/Ta3N5 photoanodes. Specifically, about 75% of the initial stable photocurrent remains after 2 h irradiation at 1.2 V vs. RHE (reversible hydrogen electrode). Meanwhile, a photocurrent density of 3.1 mA cm−2 has been achieved on Co3O4/Ta3N5 photoanode at 1.2 V vs. RHE with backside illumination under 1 sun AM 1.5 G simulated sunlight. The reason for the relatively high stability is discussed on the basis of electron microscopic observations and photoelectrochemical measurements, and the surface nitrogen content is monitored by X‐ray photoelectron spectroscopic analysis.

Construction of stable Ta 3 N 5 /g-C 3 N 4 metal/non-metal nitride hybrids with enhanced visible-light photocatalysis

“…Theoretically, smaller PL intensity means lower recombination rate of photo-generated electrons and holes, resulting in higher photocatalytic activity [38]. 19 The findings in PL spectra indicate that the introduction of Ta …”

“…The prospective candidate Ta 3 N 5 has been used in the field of the solar water splitting and decomposition of toxic organic molecules [17][18]. However, nitrogen anions in Ta 3 N 5 can readily be oxidized to N 2 by photogenerated holes during the photocatalytic process, so bare Ta 3 N 5 shows poor photocatalytic activity and stability, which hinders its practical applications [19][20]. To improve the photocatalytic activity and stability of Ta 3 N 5 , a strategy must be designed for prompting separation of the photogenerated electrons and holes in the photocatalytic activities in situ template-free method [22].…”

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

“…On the other hand, owing to the water oxidation reaction process involving the removal of protons, it is imaginable that slow oxidation reaction kinetics may be not only blocked by the inappropriate modification of OECs, but also closely interrelated with the poor proton-accepting capability of the supporting electrolyte [54,55]. In K2SO4 neutral electrolyte, the diffusion process of protons is slow so that the photogenerated holes accumulation and the slow water oxidation kinetics of photoanodes are unavoidable [10,56,57]. For the BiVO4 photoanode, the photogenerated hole accumulation usually results in the recombination of photogenerated carriers, which is unfavourable for water splitting [13].…”

“…Comparing with K2SO4, the mechanism of KHCO3 weak alkaline electrolyte in promoting the PEC performance of BiVO4/NiFe-LDH photoanode can be explained by its better proton-accepting ability. The reasons of the bad PEC stability and activity of BiVO4/NiFe-LDH in K2SO4 may be attributed to the following two points [10,[55][56][57]: (1) the poor chemical stability of NiFe-LDH due to the acidic neighbouring environment after O2 evolution; (2) the kinetic bottleneck of water oxidation associated with low protons removing rate in K2SO4 electrolyte. The above results suggest that it is important to facilitate the kinetics of water oxidation, which is associated with both the OECs and electrolytes.…”

Microstructure Effects on the Water Oxidation Activity of Co3O4/Porous Silica Nanocomposites

“…11 Cobalt oxide-decorated gold 12 or graphene 13 electrodes show some of the best catalytic performance in oxygen reduction and evolution reactions, whereas Co 3 O 4 -modified Ta 3 N 5 photoanodes show enhanced performance and stability. 14,15 Co(II)-modified, fluorine-doped tin oxide has high catalytic activity, 16 as do self-repairing cobalt phosphate films 17 and diamondsupported Co 2 O 3 nanoparticles. 18 Mesoporous Co 3 O 4 prepared by hard-templating methods show increased stability and electrocatalytic ability.…”