Session: 17-01-01 Research Posters

Paper Number: 69712

Start Time: Thursday, 02:25 PM

69712 - Enhanced Solar-Driven Photoelectrochemical (Pec) Splitting by Heterojunctions at Multiphase Tio2 Interfaces 

Solar-driven water-splitting is a feasible route for hydrogen generation, since the process emulates the conversion in plants through natural photosynthesis (NPS). Light energy is converted into chemical energy, like oxygen and carbohydrate. Since the first study on photochemical photolysis of water by Fujishima and Honda in 1972, the photo-electrochemical (PEC) splitting of water technology has drawn much attention for its potential applications in renewable energy utilization and energy structure transition.

In the PEC water-splitting process, hydrogen is produced from water using inexhaustible sunlight and specialized semiconductors, making it a more environmentally friendly and feasible way without carbon dioxide or dust production from reactions. However, it remains a technological challenge to construct a novel catalyst to drive the reaction, at a scale and cost comparable to fossil fuels. Significant advances in light utilization and high solar to hydrogen conversion efficiency are still required. Compared with the photocatalytic process, water splitting in a PEC cell employs a semiconductor electrode to separate hydrogen and oxygen production spatially: the photoanode for oxidation, and the cathode for reduction. During this process, an external bias potential is required to improve hydrogen generation highly. Designing a novel nanostructured photoelectrode with an excellent visible light response and stability will bring new advances to this field. Of all the catalysts, TiO₂, WO₃, BiVO₄, Fe₂O₃, and ZnO have been extensively studied in the PEC process. Among the photocatalysts, TiO₂ is a promising visible-light-driven photocatalytic material with a band gap of 3.2 eV of anatase phase, and 3.0 eV of rutile phase. As an oxide, TiO₂ can be used to split water directly. Varieties of strategies (such as nanostructure, doping, surface modification) have been conducted for enhancing the energy conversion efficiency of TiO₂ photoelectrodes.

A series of TiO₂ rutile and anatase nano-branched electrodes were prepared by combining electrospinning and hydrothermal processes in this work. The experimental results showed this branched multiphase TiO₂ film was a combination of anatase nanofiber and rutile nanorods. Within the interface of multiphase TiO₂, the homojunction promoted the charge separation, improved the charge transfer rate, and then acquired a relatively high efficiency for photo-electrochemical water splitting. The photo-electrochemical test results showed that 3 hours' hydrothermal deposition yielded the highest photo-electrochemical performance for the branched multiphase TiO₂ film. The photocurrent density reached 0.95 mA/cm² at the 1.0 V vs. Ag/AgCl. Moreover, this work described here provides a generic route for fabricating other multiple metal oxide photoelectrodes for photo-electrochemical applications.

Presenting Author: Xiangkun (Elvis) Cao Cornell University

Authors:

Xiangkun (Elvis) Cao Cornell University
Xu Liu Cornell University