Advanced Energy Materials and Research

Biography

Biography: Sabiha Akter Monny

Abstract

Photoelecctrochemcial water splitting provides an attractive method to convert the abundant solar energy into sustainable and clean hydrogen energy. The greatest challenge is how to develop efficient and stable photoelectrodes, including photoanodes and photocathodes. Comparing to the widely studied photoanodes, the photocathodes have been paid less attention due to the scarcity of suitable semiconductor candidates. Some available photocathodes derived from p-type semiconductors such as single crystal Si, chalcogenide (e.g., CuInGaSe) are either not stable or too expensive to realize large scale application. Herein, a promising p-type semiconductor, CuBi₂O₄, has been used to fabricate efficient photocathode. Moreover, combining the CuBi₂O₄ photocathode with well-developed BiVO₄ photoanode, it is able to demonstrate unbiased sunlight-driven solar water splitting. CuBi₂O₄ electrodes were prepared with electrodeposited BiOI and copper acetylacetonate as precusor after heating in air at 450^oC for 4 hours. The CuBi₂O₄ photocathode possesses a porous nano branch strucutre and showed a photocurrent of -0.95 mA/cm² at 0.21 VRHE along with an onset potential at 1.1 VRHE in Sodium Phosphate (~pH 7) electrolyte. With the presence of electron scavengers, the photocurrent was further enhanced to -2.4 mA/cm² at 0.48 VRHE. The incident photon-to-current efficiency showed a threshold at ca. 620 nm, suggesting a broad light harvesting range of the CuBi₂O₄ photocathode. Furthermore, the large onset potential of CuBi₂O₄ photocathode makes it feasible to realize unbiased photoelectrode water splitting when combined with suitable photoanode, such as BiVO₄.

Figure: The photoresponse of CuBi₂O₄ and BiVO₄ under chopped light. In conclusion, we have developed a new method for fabricating the state-of-the-art CuBi₂O₄ photocathode. Further combining with BiVO₄ photoanode, it can achieve efficient unbiased water splitting.