Nano-engineering of p–n CuFeO₂-ZnO heterojunction photoanode with improved light absorption and charge collection for photoelectrochemical water oxidation

Abstract

The effective utilization of abundant visible solar light for photoelectrochemical water splitting is a green approach for energy harvesting, to reduce the enormous rise of carbon content in the atmosphere. Here, a novel efficient design strategy for p-n type nano-heterojunction photoanodes is demonstrated, with the goal of improving water splitting efficiency by growing low band gap p-CuFeO nanolayers on n-ZnO nanorods by an easy and scalable electrochemical route. The photoconversion efficiency of p-n CuFeO/ZnO photoanodes is found to be ∼450% higher than that of pristine ZnO nanorod electrodes under visible solar light illumination (λ > 420 nm, intensity 10 mW cm). The p-n CuFeO/ZnO nano-engineering not only boosts the visible light absorption but also resolves limitations regarding effective charge carrier separation and transportation due to interfacial band alignment. This photoanode also shows remarkably enhanced stability, where the formation of p-n nano-heterojunction enhances the easy migration of holes to the electrode/electrolyte interface, and of electrons to the counter electrode (Pt) for hydrogen generation. Therefore, this work demonstrates that p-n nano-engineering is a potential strategy to design light-harvesting electrodes for water splitting and clean energy generation.

Investigating the Role of Oxygen Vacancies and Lattice Strain Defects on the Enhanced Photoelectrochemical Property of Alkali Metal (Li, Na, and K) Doped ZnO Nanorod Photoanodes

“…ZnO NRs array was synthesized on the conducting surface of FTO glass substrate by a simple two‐step wet chemical deposition process ,. First the FTO substrate (1.5 cm×1 cm×2.2 mm) was cleaned thoroughly by double de‐ionized water, ethanol and acetone, respectively.…”

“…The naturally abundant metal oxide semiconductors have shown immense potential for energy conversion in PEC cell. Among various oxide semiconductors, ZnO has been extensively investigated as photoanode for PEC water splitting because of its favorable band‐edge positions, superior chemical and thermal stability, relatively higher exciton binding energy of ∼60 meV which is higher than the room temperature thermal energy ( kT ), non‐toxicity and low cost . Still, the overall photoconversion efficiency of ZnO is considerably inadequate because of its large band gap energy, poor visible light absorption, low carrier separation efficiency, higher recombination rate of the photogenerated electron‐hole pairs and sluggish carrier transport ,,.…”

Photoelectrochemical CO2 Reduction via Cu2O/CuFeO2 Hierarchical nanorods photocatalyst

“…[23,24] Since it has a high absorption coefficient for efficiently absorbing light within the solar spectrum and is abundant on earth, it has attracted worldwide attention. [25,26] CuFeO 2 is capable of reducing carbon dioxide and is very suitable for forming a hierarchical structure with Cu 2 O because its band position is similar to that of Cu 2 O. [6,[27][28][29][30] According to several previous studies, CuFeO 2 /CuO composites have been fabricated as photocatalysts.…”

“…CuFeO 2 is a p‐type semiconductor material showing high stability in aqueous electrolytes . Since it has a high absorption coefficient for efficiently absorbing light within the solar spectrum and is abundant on earth, it has attracted worldwide attention . CuFeO 2 is capable of reducing carbon dioxide and is very suitable for forming a hierarchical structure with Cu 2 O because its band position is similar to that of Cu 2 O .…”

Integration of LaCo(OH)x Photo-Electrocatalyst and Plasmonic Gold Nanoparticles with Sb-Doped TiO2 Nanorods for Photoelectrochemical Water Oxidation

“…The significantly large transient decay time of the LaCo­(OH) x /Au/Sb-TiO 2 (3 min) photoelectrode results from remarkably reduced recombination of photogenerated electron–hole pairs. The decrease of the value of transition decay time for LaCo­(OH) x /Au/Sb-TiO 2 (5 min) compared to that of the LaCo­(OH) x /Au/Sb-TiO 2 (3 min) photoanode is because of the increased thickness of the LaCo­(OH) x layer of the LaCo­(OH) x /Au/Sb-TiO 2 (5 min) electrode, which contains more surface defects to trap the photocarriers during charge transportation . It is evident that the heterostructure formation increases the transient decay time, reducing the electron–hole pair recombination.…”