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