Modification of Hematite Photoanode with Cobalt Based Oxygen Evolution Catalyst via Bifunctional Linker Approach for Efficient Water Splitting

Abstract

The modification of hematite photoanode with cheap, scalable, and efficient oxygen evolution catalyst is an essential step for its practical application for solar fuel production. In this paper, a simple and water-based method has been developed for the modification of hematite surface with cobalt based oxygen evolution catalyst using 3-aminopropionic acid (APA) as a bifunctional linker. APA exists in an aqueous solution at pH 6.1 in zwitterionic form and thus it has a positive charge on the protonated amino group and a negative charge on the carboxylate group. The carboxylate groups of APA molecules can thus interact with the protonated surface hydroxyl groups of hematite whereas the amino groups tether the cobalt ions. The hematite photoanodes were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy and inductively coupled plasma optical emission spectroscopy. The photoelectrochemical measurements indicated that Co/APA–hematite photoa...