Journal
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
Volume 11, Issue 15, Pages 5895-5907Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acssuschemeng.2c07258
Keywords
hematite; in situ Nb-doping; microwave treatment; Co(OH)x cocatalyst; water oxidation kinetics
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To improve the performance of hematite (alpha-Fe2O3) photoanode, we developed a Nb-doped and Co(OH)x cocatalyst-deposited alpha-Fe2O3 thin film photoanode (Nb-HT/Co(OH)x) through in situ diluted hydrothermal and microwave-assisted methods. The Nb-HT/Co(OH)x photoanode exhibited significantly higher photocurrent density and charge separation efficiency compared to the Bare-Fe2O3 photoanode. This bulk and surface modification strategy provides a new approach for constructing stable photoanodes for solar energy conversion.
Herein, in order to improve the conductivity and slack water oxidation kinetics of the hematite (alpha-Fe2O3) photoanode, we propose the Nb-doped and Co(OH)x cocatalyst-deposited alpha-Fe2O3 thin film photoanode (Nb-HT/Co(OH)x) via in situ diluted hydrothermal and microwave-assisted methods. The as-prepared Nb-HT/ Co(OH)x thin-film photoanode exhibited a photocurrent density of 1.78 mA cm-2 at 1.23 V versus a reversible hydrogen electrode (RHE), which is 1.7-fold higher than that of the Bare-Fe2O3 photoanode. The dual effect of Nb-doping and Co(OH)x deposition markedly improved the PEC performance through enhancing the charge carrier mobility and donor density in hematite, as well as accelerating the interfacial charge transfer kinetics at the electrode/electrolyte interface of the alpha-Fe2O3 thin film photoanode. The Nb-HT/Co(OH)x photoanode displayed a high charge separation efficiency of 90% (at 1.23 VRHE) and excellent stability over a 10 h period without any decrease. Detailed electrochemical analyses using electrochemical impedance spectroscopy (EIS), open circuit potential (OCP), and accumulated charge density techniques disclosed the charge separation and transfer processes. This strategy of bulk and surface modification highlights a new approach to constructing a stable photoanode for sustainable solar energy conversion.
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