Efficient Nanoporous Hematite Photoanodes Prepared by Electron Beam Evaporation and Au Modification

Abstract

The water oxidation efficiency of hematite photoanodes is mainly limited by low visible light absorption and short hole diffusion length. Herein, we report on production of nanoporous columnar hematite films modified with Au nanoparticles (NPs) to overcome these drawbacks. The hematite films are prepared by electron beam evaporation. By optimization of deposition conditions including film thickness, annealing and performing the evaporation under oblique angle, an efficient photoelectrochemical (PEC) performance is achieved from the pristine hematite photoanode. Then, Au NPs are infiltrated into the hematite films by a spin coating process. The water oxidation of hematite films is further enhanced after Au modification. The most efficient electrode generates a photocurrent density of 2.7 mA cm−2 at 1.5 V (RHE), showing about two‐fold improvement relative to that of bare hematite. Optical and electrochemical analyses suggest that the improvement after Au modification can be attributed to plasmonic and facilitating surface charge transfer. The contributions of different plasmonic mechanisms to the photocurrent enhancement are qualitatively discussed based on optical characterization and electromagnetic simulations. Electrochemical impedance spectroscopy is carried out to confirm the improvement of surface charge transport by the Au NPs. Our findings show that Au modification is a favorable strategy to improve the PEC performance of hematite photoanodes prepared by PVD methods.

Hematite Surface Modification toward Efficient Sunlight-Driven Water Splitting Activity: The Role of Gold Nanoparticle Addition

“…The contribution of light in the formation of an oxidized product can also be seen in Figure S5. The appearance of this hydrated/oxidized gold phase in the interface, the electrode/electrolyte may affect the conductivity impairing the photocatalytic performance because of the passivation layer on the surface formation, decreasing the number of the transferred charge . Most notably, it has been reported that the appearance of the oxidized gold species on metals can induce a reduction of the metal work function. ,, This implies that under PEC conditions, the presence of chemisorbed species (Au–O) plays a role in the photoactivity of AuNP.…”

The Synergy of Topographical Micropatterning and Ta|TaCu Bilayered Thin Film on Titanium Implants Enables Dual‐Functions of Enhanced Osteogenesis and Anti‐Infection

“…Despite with a bilayered thin film as our model system, it is easy to extend our strategy to fabricate nano‐multilayered coatings. In addition, the EBE deposition we used in this study is a powerful thermal evaporation approach to deposit nanostructured coatings with controlled thickness and superimposed nanotopographical features and enables the evaporation of metals with very high melting points and a high material utilization efficiency on the outer surface of substrates, even with complex geometries, [ 53 ] indicating a wide applicability of this approach to diverse functional metallic ions delivery.…”

Photoelectrochemical water splitting by hematite boosted in a heterojunction with B-doped g-C3N4 nanosheets and carbon nanotubes

“…Various strategies have been employed to overcome the limitations of hematite, including heterojunction construction, 20 doping with metals and nonmetals, [21][22][23] morphology advancement, 24 and co-catalyst loading. 25,26 Among these, forming nanoscale heterojunctions by coupling a-Fe 2 O 3 with a second semiconductor has proven effective, leveraging appropriate bandgap overlap and enhanced charge separation at the junction interfaces.…”