Inverse Photoelectrochemical Cell

Abstract

The splitting of water with sunlight using photoelectrochemical cell (PEC) to produce hydrogen is a promising avenue for sustainable energy production. The greatest virtue of PEC is that it uses sunlight as the only source to split water, but its efficiencies are still quite low due to poor performances of the available materials (such as SrTiO3). Consequently, another way of PEC research has been developed. By simultaneously using sunlight and electricity as energy source, PEC can get a larger current at a lower voltage, i.e., hydrogen can be made under the voltage below 1.23V, the minimum voltage required by electrolysis of water. But so far the efficiencies of the mainstream materials (such as TiO2) remain low. Where is the future development direction of PEC? Here we propose a new PEC model. Its operating principle is quite the opposite of the aforesaid conventional PEC, that is, the previous photoanode/photocathode is converted into the present photocathode/photoanode. It can also obtain high current under low voltage, even near zero voltage in extreme conditions. A basic single configuration and an improved n-p configuration were designed. We reselected materials for photoelectrodes, and confirmed its feasibility successfully. Two preliminary results were obtained from two contrasts: whether compared with water electrolysis or conventional PEC water splitting, the inverse PEC showed promising superiority.