Biomimetic Adhesives for Photoelectrochemical Water Splitting

Abstract

Hematite (a-Fe2O3) is a very promising photoanode material for solar water oxidation due to its abundance, non-toxicity, small band gap, and high stability. However, they have poor electrochemical properties such as short hole diffusion length and a large requisite overpotential for water oxidation. In principle, these problems can be solved by synthesizing nanostructured hematite and modifying its surface with water oxidation catalysts. However, there still remain challenges such as difficulties in controlling the amount of catalyst loading and its optimization. In the present study, we report that a simple in-situ electropolymerization of dopamine enables deposition of polydopamine film incorporating molecular oxide clusters (commonly referred to as polyoxometalates (POMs)) on hematite. In this method, we can easily control the thickness of polydopamine film by regulating the number of electropolymerization cycle and the amount of catalysts incorporated by varying the concentration of precursor solution. As a result, polydopamine-POM coated hematite shows highly improved photocatalytic activity in terms of photocurrent density and onset potential.