The effect of Mg-doping and Cu nonstoichiometry on the photoelectrochemical response of CuFeO2

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2017, Vol.5 (1), p.165-171
• Main Authors: Wuttig, Anna, Krizan, Jason W, Gu, Jing, Frick, Jessica J, Cava, Robert J, Bocarsly, Andrew B
• Format: Article
• Language: English
• Subjects: Carrier density; Defects; doping of CuFeO2; ENERGY STORAGE; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Magnesium; Majority carriers; MATERIALS SCIENCE; novel semiconductor electrodes; p-CuFeO2 based electrodes; p-type photocathodes; Pellets; Photoelectrochemical devices; photoelectrochemistry; RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY; SOLAR ENERGY; Solubility; Tuning
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c6ta06504j

We report the tuning of CuFeO2 photoelectrodes by Mg doping and Cu deficiency to demonstrate the effects of carrier concentration on the photoresponse. Carrier type and concentration were quantitatively assessed using the Hall effect on pure, Mg-incorporated, and Cu-deficient pellets (CuFe1-xMgxO2 and Cu1-yFeO2, x = 0, 0.0005, 0.005, 0.02, and y = 0.005, 0.02) over the range of thermodynamic stability achievable using solid-state synthesis. The same samples were used in a photoelectrochemical cell to measure their photoresponse. We find that the material with the lowest p-type carrier concentration and the highest carrier mobility shows the largest photoresponse. Furthermore, we show that increasing the p-type carrier concentration and thus the conductivity to high levels is limited by the delafossite defect chemistry, which changes the majority carrier type from p-type to n-type near the Mg solubility limit (x = 0.05) and at high Cu defect concentrations.