Mesoporous ZnFe₂O₄ Photoanodes with Template‐Tailored Mesopores and Temperature‐Dependent Photocurrents

Abstract

Mesoporous ZnFe O photoanodes have been prepared via dip-coating utilizing the evaporation-induced self-assembly of two different block-copolymer templates to investigate the influence of pore geometry on the photoelectrochemcial performance of those earth-abundant photoelectrodes. The use of commercial block copolymers, triblock copolymer Pluronic F127 and the diblock copolymer PIB3000 as templates, leads to different pore morphologies under identical preparation conditions due to different polymer stabilities. Interestingly, pore morphology in mesoporous ZnFe O turned out to be less important for the photoelectrochemical performance. Contrary, sufficiently developed crystalline domains gained through optimized temperature treatment resulted in maximum photoelectrochemical performance among the investigated samples. This disproves the necessity of expensive, tailor-made polymer soft templates to synthesize high-performing mesoporous ZnFe O photoanodes.

Ordered Mesoporous LiFe5O8 Thin‐Film Photoanodes for Water Splitting

“…When not employed as single‐phase electrodes, spinel ferrites are also often used in the form of composites as a kind of sensitizer for better charge separation, e. g. in combinations like ZnFe 2 O 4 /α‐Fe 2 O 3 or NiFe 2 O 4 /TiO 2 . Recently, it has been shown that the photoelectrochemical properties of ZnFe 2 O 4 can be tailored by mesostructural engineering . To this end, large‐pore mesoporous ZnFe 2 O 4 thin films, prepared using an evaporation‐induced self‐assembly (EISA) process along with different polymer structure‐directing agents, were applied.…”

Mesoporous NiFe2O4 with Tunable Pore Morphology for Electrocatalytic Water Oxidation

“…Among the multiple transition metal oxides, ferrites with the general formula M II Fe 2 O 4 (M=Ca, Zn, Mg, Ni, Co, Mn etc .) have gained considerable attention due to their compositions made up from earth‐abundant elements and widespread application fields besides electrocatalysis [12–15] in gas sensing, [16,17] and photocatalysis/photoelectrochemistry [18–27] . Especially nickel ferrite has been considered as efficient OER electrocatalyst, with outstanding high stability in alkaline media, excellent redox properties, and ferromagnetism facilitating the catalyst separation from solution [28,29] .…”

“…have gained considerable attention due to their compositions made up from earth-abundant elements and widespread application fields besides electrocatalysis [12][13][14][15] in gas sensing, [16,17] and photocatalysis/photoelectrochemistry. [18][19][20][21][22][23][24][25][26][27] Especially nickel ferrite has been considered as efficient OER electrocatalyst, with outstanding high stability in alkaline media, excellent redox properties, and ferromagnetism facilitating the catalyst separation from solution. [28,29] Already in 1999, N. K. Singh and R. N. Singh showed that the inverse spinel NiFe 2 O 4 is a highly active material in the electrocatalytic water oxidation with an overpotential of 379 mV at a current density of 100 mA cm À 2 , which outcompetes pure iron oxide (spinel Fe 3 O 4 ).…”

Effect of the Degree of Inversion on the Photoelectrochemical Activity of Spinel ZnFe2O4

“…During the last few years, there has been increasing interest in the study of spinel ZnFe 2 O 4 (ZFO) as a photoanode material for photoelectrochemical water oxidation [1][2][3]. As new scientific investigations in this field are reported, differences concerning the photoelectrochemical activity of ZFO photoanodes prepared by different routes have become evident [4][5][6][7][8][9][10][11]. It is well known that ZFO exhibits a variable structure where the distribution of Zn 2+ and Fe 3+ cations between octahedral and tetrahedral sites within the crystal lattice depends on the synthetic conditions [12][13][14][15][16][17][18].…”