Electrochemical Synthesis of Photoelectrodes and Catalysts for Use in Solar Water Splitting

Electrochemical Synthesis of Photoelectrodes and Catalysts for Use in Solar Water Splitting

Donghyeon Kang, Tae Woo Kim, Stephen R. Kubota, Allison C. Cardiel, Hyun Gil Cha, and Kyoung-Shin Choi*

Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States

Chemical Reviews: http://pubs.acs.org/doi/pdf/10.1021/acs.chemrev.5b00498
DOI: 10.1021/acs.chemrev.5b00498

Abstract: This review focuses on introducing and explaining electrodepostion mechanisms and electrodeposition-based synthesis strategies used for the production of catalysts and semiconductor electrodes for use in water-splitting photoelectrochemical cells (PECs). It is composed of three main sections: electrochemical synthesis of hydrogen evolution catalysts, oxygen evolution catalysts, and semiconductor electrodes. The semiconductor section is divided into two parts: photoanodes and photocathodes. Photoanodes include n-type semiconductor electrodes that can perform water oxidation to O2 using photogenerated holes, while photocathodes include p-type semiconductor electrodes that can reduce water to H2 using photoexcited electrons. For each material type, deposition mechanisms were reviewed first followed by a brief discussion on its properties relevant to electrochemical and photoelectrochemical water splitting. Electrodeposition or electrochemical synthesis is an ideal method to produce individual components and integrated systems for PECs due to its various intrinsic advantages. This review will serve as a good resource or guideline for researchers who are currently utilizing electrochemical synthesis as well as for those who are interested in beginning to employ electrochemical synthesis for the construction of more efficient PECs.

Phase transition-induced band edge engineering of BiVO4 to split pure water under visible light

                       

Won Jun Jo^a,¹,Hyun Joon Kang^b,¹,Ki-Jeong Kong^c, Yun Seog Lee^d, Hunmin Park^b, Younghye Lee^b, Tonio Buonassisi^d,  Karen K. Gleason^a, and Jae Sung Lee^e,²                           

^aDepartment of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; ^bDepartment of Chemical Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea;^cKorea Institute of Chemical Technology, Daejeon 305-343, Korea; ^dDepartment of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;^eSchool of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798, Korea

 

Abstract

Through phase transition-induced band edge engineering by dual doping with In and Mo, a new greenish BiVO₄ (Bi_1-XIn_XV_1-XMo_XO₄) is developed that has a larger band gap energy than the usual yellow scheelite monoclinic BiVO₄ as well as a higher (more negative) conduction band than H⁺/H₂ potential [0 V_RHE (reversible hydrogen electrode) at pH 7]. Hence, it can extract H₂ from pure water by visible light-driven overall water splitting without using any sacrificial reagents. The density functional theory calculation indicates that In³⁺/Mo⁶⁺ dual doping triggers partial phase transformation from pure monoclinic BiVO₄ to a mixture of monoclinic BiVO₄ and tetragonal BiVO₄, which sequentially leads to unit cell volume growth, compressive lattice strain increase, conduction band edge uplift, and band gap widening.

http://www.pnas.org/content/112/45/13774.full