Enhanced Oxygen Evolution Reaction Activity of Nanoporous SnO₂/Fe₂O₃/IrO₂ Thin Film Composite Electrodes with Ultralow Noble Metal Loading

Abstract

A conductive SnO2 layer and small quantities of IrO2 surface cocatalyst enhance the catalytic efficiency of nanoporous Fe2O3 electrodes in the oxygen evolution reaction at neutral pH. Anodic alumina templates are therefore coated with thin layers of SnO2, Fe2O3, and IrO2 by atomic layer deposition. In the first step, the Fe2O3 electrode is modified with a conductive SnO2 layer and submitted to different postdeposition thermal treatments in order to maximize its catalytic performance. The combination of steady‐state electrolysis, electrochemical impedance spectroscopy, X‐ray crystallography, and X‐ray photoelectron spectroscopy demonstrates that catalytic turnover and e− extraction are most efficient if both layers are amorphous in nature. In the second step, small quantities of IrO2 with extremely low iridium loading of 7.5 µg cm−2 are coated on the electrode surface. These electrodes reveal favorable long‐term stability over at least 15 h and achieve maximized steady‐state current densities of 0.57 ± 0.05 mA cm−2 at η = 0.38 V and pH 7 (1.36 ± 0.10 mA cm−2 at η = 0.48 V) in dark conditions. This architecture enables charge carrier separation and reduces the photoelectrochemical water oxidation onset by 300 mV with respect to pure Fe2O3 electrodes of identical geometry.

Synthesis of Host‐Guest Hematite Photoelectrodes for Solar Water Splitting

“…300 mV), from ca . 1.00 V RHE to 0.70 V RHE ; this shift is similar to the ones obtained with co‐catalysts made of noble materials, such as IrO 2 …”

Strategic Atomic Layer Deposition and Electrospinning of Cobalt Sulfide/Nitride Composite as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

“…As both SFCNF/Co 1− x S and SFCNF/Co 1− x S@CoN show crystalline features according to TEM results, X‐ray diffraction (XRD) analysis was conducted to further study crystallographic structures, which are thought to be crucial for functional performance. [ 19 ] In blue plot of Figure a, diffraction peaks at 2θ = 30.5°, 35.2°, 46.8°, 54.3°, 62.3°, 66.2°, 72.9°, and 74.4° are readily indexed to characteristic (100), (101), (102), (110), (103), (201), (004), and (202) planes of face‐centered cubic Co 1− x S (PDF No. 42–0826), respectively.…”

Ordered SnO2 nanotube arrays of tuneable geometry as a lithium ion battery material with high longevity

“…6 reveals that crystalline SnO 2 is obtained from ALD without annealing necessary, as has been reported before for layers of sufficient thickness and depending on deposition temperature and substrate. 57,58 Therefore, the amount of hydrated material (presumably amorphous) is low in the bulk. The very broad signal stretching from 20 to 40 and evident of a large amount of amorphous material can be attributed to the alumina matrix, since it is absent of data recorded for planar lms on silicon wafers in grazing incidence (0.6 ).…”