A ZnO/ZnFe₂O₄ uniform core–shell heterojunction with a tubular structure modified by NiOOH for efficient photoelectrochemical water splitting

Abstract

It is known that heterojunction photoelectrodes can improve light absorption and accelerate the separation of photogenerated carriers in the field of photoelectrochemical (PEC) water splitting. However, the key to efficient photoelectrochemical performance is to build heterojunctions with a narrow band gap semiconductor loaded on a wide band gap semiconductor uniformly and densely. Herein, a ZnO/ZnFe2O4 uniform core-shell heterojunction photoelectrode is prepared by a simple ion etching method. Moreover, the chemical reaction process and mechanism are discussed in detail. The ZnO/ZnFe2O4 photoelectrode shows a higher photocurrent density (0.29 mA cm-2 at 1.23 V vs. RHE) compared with that of ZnO (0.17 mA cm-2 at 1.23 V vs. RHE). Furthermore, the PEC performance of ZnO/ZnFe2O4 is optimized by depositing NiOOH; the photocurrent density of ZnO/ZnFe2O4/NiOOH is 0.48 mA cm-2 at 1.23 V vs. RHE. The remarkable PEC performance of ZnO/ZnFe2O4/NiOOH benefits from the following important factors: (i) the uniformity and nanotube structure of the ZnO/ZnFe2O4 heterojunction; (ii) the excellent light harvesting ability; and (iii) the reduced photogenerated electron-hole pair recombination rate. This work provides new insights into designing heterojunction systems for efficient photoelectrochemical water splitting.

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

“…[161][162][163][164][165] Quiñonero and Gómez [163] coupled a small amount of Ni(OH) 2 on α-Fe 2 O 3 films for improved PEC water oxidation activity. [161][162][163][164][165] Quiñonero and Gómez [163] coupled a small amount of Ni(OH) 2 on α-Fe 2 O 3 films for improved PEC water oxidation activity.…”

n–n ZnO–Ag2CrO4 heterojunction photoelectrodes with enhanced visible-light photoelectrochemical properties

“…9,10 To overcome these difficulties, the constructed heterojunction between ZnO and narrow-band-gap semiconductors with appropriate energy levels can not only broaden the light absorption region but also facilitate the separation and transfer of photocarriers. [11][12][13][14][15] In particular, nanostructure composites containing n-n heterojunctions with direct contact between two n-type semiconductors have widespread potential applications because of the formed electric eld produced at the junction, resulting in efficient charge separation, as demonstrated in InN/ZnO, 16 Fe 2 O 3 /ZnO, 17 BiVO 4 /P25, 18 CdWO 4 /Bi 2 O 2 CO 3 (ref. 19) and ZnO/ Ag 3 VO 4 .…”

Fabrication of 2D/0D Heterojunction Based on the Dual Controls of Micro/Nano‐Morphology and Structure Towards High‐Efficiency Photocatalytic H2 Production

“…As for the reported sustainable energy, hydrogen (H 2 ) energy is undoubtedly the best choice due to its clean, non-polluting, and low-cost advantages. [1][2][3][4][5][6] The semiconductor photocatalysis technology has become increasingly promising one for H 2 production from water splitting in view of its energysaving, eco-friendly and wide-application prospects. [7][8][9] For photocatalysis technology itself, however, it is very important to the oriented design and preparation of new-type photocatalysts with excellent performances.…”