Demonstration of Enhanced Carrier Transport, Charge Separation, and Longterm Stability for Photocatalytic Water Splitting by a Rapid Hot Press Process
In this study, a rapid hot press process (HPP) has been adopted to enhance the efficiency of photocatalytic water splitting in TiO2-Fe2O3 metal oxide cocatalyst. Without complicated nanostructure fabrication, the hot press sample demonstrated more than 6-fold photocurrent enhancement compared to the untreated sample at an applied voltage of 1.2 V. This enhancement is attributed to the improvement of carrier transport properties in the TiO2-Fe2O3 matrix due to a significant reduction of the film thickness after the hot press process. In addition to the enhanced photocurrent, we observe a significant improvement of the stability and resistance to corrosion in a 1M NaOH electrolyte due to the increase in stiffness of the thin film from 80 Gpa to 125 Gpa after the hot press process. The improvements of carrier transport and charge separation are measured using photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) spectroscopy. The crystallinity and grain size of TiO2-Fe2O3 has been characterized by high-resolution transmission electron microscopy (HRTEM) before and after hot press process. We also examined the plasmonic resonance effect by integration of plasmonic gold nanoparticles (NPs) into this hot pressed TiO2-Fe2O3 cocatalyst to achieve the further enhancement of hydrogen production.