New Photoelectrochemical Reactor for Hydrogen Generation: Experimental Investigation

Abstract

In the scope of this study, a new photoelectrochemical (PEC) reactor, comprising a novel geometry for effective absorption of sunlight, is developed conceptually, and tested and assessed experimentally. The conic mesh structure of the photoelectrode offers maximizing the performance via passive tracking of solar light during daylight. In sequence, electrodeposition and sol–gel dip coating techniques are practiced, fabricating a copper oxide semiconductor as a working electrode and a titanium dioxide-coated electrode as the counter electrode. The new reactor concept is experimentally assessed for various conditions through electrochemical tests including open circuit potential, linear sweep voltammetry, cyclic voltammetry, and PWR potentiostatic tests. Energy and exergy efficiencies and hydrogen production rates are evaluated for various experimental conditions implying with and without light. The highest hydrogen production rate corresponding to 4.48 μg H2/s at near-atmospheric conditions (25 °C temperature and 101.3 kPa pressure) is obtained with the applied external bias of 2.25 V, where the reactor operates under artificial solar light with an intensity of 1000 W/m2. The produced photocurrent density is determined to be 1.81 mA/cm2, corresponding to a photo-conversion efficiency of 1.84%. For these operational conditions, the energetic and exergetic efficiencies of the reactor are evaluated as 0.866 and 0.878%, respectively. Without light case, the PEC reactor acting as an electrolyzer operates with energetic and exergetic electrolysis efficiencies of 56.51 and 54.38%, respectively.