Enhanced Oxygen Evolution Reaction Activity of LaFeO3 with Co-Pi Decoration

With the continuing energy demand and environmental deterioration by conventional coal and gasoline, it is urgent to develop renewable energy. Among many methods, water splitting to generate clean hydrogen fuels is among the most promising one. Many perovskites such as SrTiO₃, NaTaO₃ and AgNbO₃ have become candidates materials for water splitting due to their high catalytic activity and flexible structures. However, the H₂ production efficiency is relatively low at visible light regime because of the large band gap of most perovskite materials. From the view point of optical absorption, LaFeO₃ with a band gap of 2.07eV ^[1] shall be a good candidate. Nonetheless, the poor oxygen evolution reaction (OER) performance of LaFeO₃severely limits its water-splitting efficiency. To solve the problem, OER improvement is needed.

RuO₂, IrO₂ and Pt are the conventional OER catalyst ^[2-3], but they are of high cost. Co-Pi, an amorphous cobalt-phosphate-based material, is reported having a low over potential for OER in the phosphate buffer solution at pH 7~8^[4] and its coating on hematite promotes the photoelecrochemistry performance effectively ^[5]. We report here the combination of the low cost Co-Pi with LaFeO₃ to enhance the OER activity of LaFeO₃. We demonstrate that an effective negative shift of 100meV for the onset potential with Co-Pi coating as OER improvement. The photoelectrochemical properties and its mechanism will also be discussed.

References:

1. K.M. Parida, Inter. J. of Hydrogen Energy, 35, 12161~12168 (2010).
2. E. Tsuji, A. Imanishi, K. I. Fukui, Y. Nakato, Electrochim.Acta, 56, 2009 (2011).
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5. D. K. Zhong, D. R. Gamelin, J. Am. Chem. Soc, 131, 6086–6087, 2009.